Space charge drives electromechanical conversion via a piezoelectric-like effect in ion implanted polymers

Space charge drives electromechanical conversion via a piezoelectric-like effect in ion implanted polymers | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Help Center Sign In Submit a Preprint Cite Share Download PDF Article Space charge drives electromechanical conversion via a piezoelectric-like effect in ion implanted polymers Peter Sherrell, Andris Šutka, Holger Fiedler, Artis Linarts, Kaspars Malnieks This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5436005/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 05 Feb, 2026 Read the published version in Physical Review Letters → Version 1 posted You are reading this latest preprint version Abstract Ion implantation is a powerful tool to modify materials chemistry and structure. The implantation process was considered to result in a net-neutral material, due to implanted ionic charge being compensated by the host materials lattice. Here, we show ion implantation into polytetrafluoroethylene (PTFE) results in an uncompensated ‘space charge’ region – requiring a reconsideration of ion implantation into polymers. This is demonstrated via electromechanical testing of Cu implanted PTFE as a triboelectric nanogenerator (TENG). Previously, ion implantation into polymers has shown to increase TENG performance, attributed to increasing the prevalence of electron transfer during contact-separation testing. This attribution to electron transfer is incorrect, with significant electromechanical conversion being observed in 1 x 10 16 Cu ions cm − 2 implanted polytetrafluoroethylene (PTFE) in both piezoelectric mode testing and in non-contact induction measurements – where electron transfer cannot occur. These results, indicate that the implantation of Cu ions creates a space charge effect in the PTFE matrix, and the subsequent charge asymmetry creates an electric field enhancing TENG performance, analogous to hybrid piezoelectric-TENGs. These results demonstrate that ion implanted polymers possess space charge and can be used directly for sensing, creating a new pathway for electromechanical conversion materials. Physical sciences/Materials science/Soft materials/Polymers Physical sciences/Physics/Chemical physics Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Flexible, polymeric, materials that convert kinetic energy into electricity (or electrical charge) are attracting immense research interest from applications ranging from powering internet-of-things (IoT) microdevices to wearable sensors to enabling green chemical transformations. Materials can achieve this through several phenomena, including ferroelectricity, 1 piezoelectricity, 2 flexoelectricity, 3 , 4 porous electrets, 5 or contact-electrification or triboelectricity. 6 Of these phenomena, triboelectricity provides key advantages over other electromechanical conversion phenomenon, as it does not require specific materials to generate charge rather the occurrence of consistent interfacial friction. 7 In particular for triboelectricity, fluoropolymers which are the most common piezoelectric and ferroelectric polymer family, can be avoided. 8 Triboelectricity is exploited through the fabrication of the triboelectric nanogenerator (TENG), whereby two dissimilar (in terms of surface chemistry, 9 – 12 mechanical properties, 13 , 14 topography, 15 , 16 or additives 17 , 18 ) 7 undergo cyclic friction, with the produced surface charge causing a Maxwells displacement current to flow on nearby electrodes. 6 While the fundamental mechanism of TENGs remains the subject of debate in literature (between electron transfer, 19 , 20 and ionic or molecular fragments 21 – 23 ), significant focus has been devoted to increasing the amount of energy a TENG can produce via directly increasing (and stabilizing 24 ) the surface charge produced at the contact interface. To increase the surface charge, different approaches have been used, such as nanostructuring , 15 , 25 adding fillers 26 , 27 increasing adhesion, modifying mechanical properties, 28 , 29 or recently ion- implantation. 30 , 31 Ion implantation provides a key capability to enhance the surface charge or arbitrary materials. This broad use case makes ion implantation a particularly attractive, yet relatively unstudied approach with recent reports should an 8x enhancement compared to equivalent pristine polymers simply be depositing 1 x 10 16 He ions cm − 2 , 31 up to a surface charge density of 332 µC m − 2 . 30 However, in this case the supposed advantage of ion implantation (to enhance arbitrary materials) failed, and only Kapton (polyimide) showed an enhancement, while other commonly used triboelectric materials including polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and fluorinated ethylene propylene (FEP) only showed a minor or no enhancement in surface charge. 30 Despite this effect, the enhancement in surface charge observed by Li et al., was immense (far outstripping the maximum surface charge achieved through manipulating adhesion, morphology, fillers, mechanical properties, or ferroelectric films (Table 1 ). Table 1 Comparison of surface charge density measured in triboelectric testing achieved by manipulating specific factors. Surface charge modification method Charge measured (µC m − 2 ) Enhancement (%) Ref(s) Adhesion 75 † 37x 28 Filler 30 42.5x 27 Mechanical Properties 12 20 x 32 Ion implantation 332 Aptos (Body) 8x 30 Ferroelectric films 353 2x 33 * The authors note that variations in testing methods leads to a significant alteration in measured charge, 34 – 36 however this charge can still provide a simple comparison tool – and the use of enhancement % enables comparison within a references own data. † Surface chemistry of the contact interface was also changed The enhancement in surface charge from io beam implantation has been attributed to enhanced electron transfer due to changes in macromolecular processes, such as breaking the chemical chain of the polymer and free radical combination to form new chemical bonds and chemical group. 31 . Ion implantation, without a doubt, will alter the molecular structure and chemistry of the polymers, and is clearly observed in Raman spectroscopy and Fourier transform infra-red (FTIR) spectroscopy. 30 , 31 , 37 However, such an effect cannot explain why the polarity inversion of Kapton in contact with Aluminium foil after implantation. The maximum charge measured for polarised ferroelectric films of 353 µC m − 2 , 33 is extremely similar to the charge density measured by ion implantation of 332 µC m − 2 , 30 this correlation does not indicate causation but does show the magnitude of the ion implantation effect. In ferroelectric polymers, triboelectric charge enhancement comes from the coupling of the electric field from the polarisation within the polymer film with the triboelectric charge transfer – producing an order of magnitude more surface charge than other techniques alone. 38 – 43 In contrast, ion implanted polymers have been reported to increase the surface charge density due to bond breakage and ionic charges enabled enhanced electron transfer, rather than coupling to existing triboelectric charge transfer mechanisms (including ion and mass transfer). 30 , 31 Ion implantation as a general technique has received significant studies focussed on implantation into ceramics, whereby the implanted ion displaces the ceramic lattice and creating defects, strain (via occupancy of interstitial sites), or substituting with lattice atoms. 44 – 48 However, these phenomenon occur very differently in polymers, which typically possess a significantly lower atomic packing density, are flexible and whose 1D-covalent bonding network enables chain rotation. While the binary elastic collision approximation remains valid, interpretation of the substrate-ion beam interaction alters dramatically. This alteration arises as; a) the flexibility of the polymer enables a higher number of charged interstitial/or void space occupancy sites; and b) the displacement of covalently bonded atoms due to the high ion energy motion causes displacement of the polymer chains the formation of a large number of vacancy-like sites. 37 , 49 Given the high dielectric nature of polymers, preventing electron flow from the drain during implantation into the polymer, even if the charge on these ions are compensated, a net charge within the polymer may be generated. The 1D nature of polymer chains, suggests that ion impacts into the polymer backbone can result in side-group loss from the polymer chain, creating volatile products and partial graphitisation (sp 2 bond formation) of the polymer backbone. 37 In addition, ion implantation can also remove surface defects and contamination, especially for low energy implantation conditions. 49 Here, we demonstrate that the enhanced triboelectric performance of ion-implanted PTFE is simply due to the introduction of these charged ions into the polymer matrix, creating a space charge effect after implantation. Implanting PTFE with 1 x 10 16 Cu + ions cm − 2 results in a material which creates significant Maxwells displacement current during motion near a parallel plate. The presence of this space charge, thus makes the implanted PTFE act as a piezoelectric material, providing an external electric field mimicking the enhancement of TENGs using hybrid piezoelectric-TENGs. 50 We demonstrate that this space charge leads to a 28.9 fold improvement in TENG mode testing of implanted PTFE against an Indium Tin Oxide (ITO) electrode proving a tool to significantly enhance electromechanical conversion within polymers for energy harvesting and sensing applications. Results Ion Implantation To investigate the function of ion implantation into polymers for TENGs, a simple experiment was conceived whereby ion implanted polymers were subjected to traditional electromechanical testing processes in piezoelectric mode (oscillatory compression without breaking contact), non-contact oscillation near a metal plate, and triboelectric ‘contact-separation mode). 51 In order to gain relevant results, from triboelectric testing Cu + was chosen for ion implantation as it is a multivalent cation with a relatively high charge density, whist being known to have extremely limited passive diffusion through PTFE. 52 Cu + was implanted into PTFE via a Penning sputter ion source at a fluence of 1 x 10 16 ions cm − 2 with an acceleration potential of 20 keV (Fig. 1 , a). 53 , 54 To ensure homogenous implantation across the target area of 13 mm x 13 mm, a raster scanning pattern was used along with a charge counter to precisely monitor deposited charge. The phenomenon occurring during ion implantation are schematically shown in Fig. 1 , a. To understand the depth and distribution of the implanted Cu + ions, monte-carlo simulations were performed to model the ion beam-polymer interactions using SDTRIP.SP version 5.07 (Fig. 1 , b). 55 The simulations use a Krypton-Carbon potential with surface binding energies of 3.49 eV, 4.79 eV and 0.82 eV for Cu, C, and F respectively. These simulations show that for the fluence of 1 x 10 16 ions cm − 2 the maximum Cu + implantation depth occurs at 240 Å, with an atomic concentration of Cu + reaching 10 − 21 (corresponding to 1 Cu + atom for every ~ 330 C atoms). This high loading of ion implantation results in a discolouration of the clear PTFE, creating a dull brown (copper) colouration across the 13 mm x 13 mm implantation area (Fig. 1 , c). This discolouration may arise from either the copper itself or mild graphitization of the PTFE. Crucially, the simulations show that within 40 Å of the surface, the Cu + atomic concentration drops to 10 − 4 (Fig. 1 , b). This atomic concentration correlates to approximately 1 Cu + atoms for every 3 x 10 5 carbon atoms – meaning there are very few Cu + atoms able near the surface of the PTFE film. These atoms are expected to be stable within the PTFE matrix, as PTFE is known to prevent ion migration through its films, and has been studied as a gas diffusion layer under a Cu catalyst extensively for CO 2 reduction, with no Cu diffusion being reported through the films. 52 In ceramics, ion beam induced interstitials can change the polarisation of ceramics through deformation of the crystal lattice, 47 , 48 which is expected to be even more pronounced within soft polymer chains. Indeed, for PTFE and PVDF mechanical stretching at elevated temperature is sufficient to cause piezoelectric alignment of a polymer chain – although the authors note there is no dipole moment across the polymer backbone to make PTFE piezoelectric. 56 In contrast to pure mechanical stretching for PTFE, 56 the piezoelectric signal after ion implantation is persistent for months, suggesting a semi-permanent dipole formation within the PTFE films. Given a large fraction of implanted Cu are expected to retain their charge post implantation, along with the depth profile of implanted Cu, a space charge region is formed within the PTFE, focussed between 100 Å and 500 Å into the 0.05 mm thick PTFE film. The localisation of space charge is expected to create an internal effective dipole, where the un-implanted back side of the PTFE possesses a relative neutral charge compared to the implanted side with a relative positive charge. The implantation of Cu + results in a discolouration of the PTFE in the implanted region (Fig. 1 , c), in line with the expected partial graphitization of the PTFE backbone. 37 Prior reports have described the use of ion implantation to enhance the measured electromechanical conversion of a TENG. However, to the best of the authors knowledge, there are no reports probing how these ion implanted polymers behave as individual electromechanical materials. Electromechanical Response from Ion Implanted Polymers To probe the presence of charge within the polymer film post Cu + implantation, non-contact oscillation (Fig. 2 , a i) of both the PTFE (Fig. 2 a, ii) and Cu-PTFE (Fig. 2 a, iii) films were performed relative to an ITO electrode. Here, the polymer films were oscillated from between 0.1 mm and 1.1 mm away from the ITO plate with the short circuit current being recorded. The pristine PTFE shows a negligible 0.2 nA peak-to-peak short circuit current due to the displacement relative to the ITO electrode displacement (Figure S1). In contrast, the Cu-PTFE film exhibits a stunning 185-fold increase in the non-contact current, achieving a peak-to-peak current of 37 nA. This result, aligns with the trend observed by Sutka et al., 57 where poled ferroelectric poly(vinylidenedifluoride) (PVDF) were found to generate voltage in non-contact mode. These voltages arise due to electrostatic induction from a moving electric field, where the moving electric field corresponds to the permanent dipole within poled PVDF. With Cu-PTFE, the space charge region localised between 100 Å and 500 Å beneath the surface of the PTFE, creates the electric field to cause the measured electrostatic induction. The strength of the electric field generated by the space charge was demonstrated by x-ray photoelectron spectroscopy (Figure S2), with all peaks shifted to higher binding energies by more than 150 eV (C 1s, F 1s, Cu 2p) due to the presence of the positive Cu + ions hindering the ejection of electrons. Piezoelectric-mode testing (Fig. 2 , b i), refers to the use of a pre-load force on the sample, to prevent any contact-separation events occurring, thus ensuring the lack of triboelectric effects when benchmarking piezoelectric materials. 36 , 51 Here, when a ΔF of 10N was applied to both the PTFE (Fig. 2 , b ii) and Cu-PTFE samples (Fig. 2 , b iii) minimal displacement was observed, indicating no contact-separation events were occurring. For the pristine film, 4 pA of short-circuit current was measured (Fig. 2 , b ii) which is considered negligible, and can arise due to stray electric fields or small friction events due to non-commensurate contact interfaces. In contrast, the Cu-PTFE demonstrated a considerable pseudo-piezoelectric effect with 40-fold increase in the peak-to-peak short-circuit current value to 165 pA (Fig. 2 , b iii). Given the lack of electrode displacement observed, this pseudo piezoelectric effect arises from the space charge region between 100 Å and 500 Å into the PTFE active as a positive region, with the neutrally charged bulk acting as a relatively negative region. Thus, compressing the Cu-PTFE moves the centre of charge of the Cu-PTFE creating induction analogous to piezoelectric compression testing. While this value of pseudo-piezoelectric effect is also smaller than reported for other piezoelectric materials, 8 , 58 , 59 or piezoelectric-like material assemblies) 5 , 60 – 65 it is higher than those measured during compression of highly charged ionic liquids or solid-polymer electrolytes. 66 The presence of this piezoelectric effect in Cu-PTFE suggests the ability to fabricate hybrid piezoelectric-TENGs (P-TENG) – which have been often reported to demonstrate exceptional triboelectric performances, far outstripping standard TENG materials. 50 , 57 , 67 – 70 Finally, given the clear demonstration of 1) space charge within the Cu-PTFE via non-contact mode testing; and 2) a permeant dipole within Cu-PTFE giving rise to a pseudo-piezoelectric effect from piezoelectric-mode testing, contact-separation “triboelectric” testing was performed to evaluate the observed triboelectrification was performed (Fig. 2 , c i). In triboelectric testing mode, Δ5 N of force is applied to the PTFE (Fig. 2 , c ii) and Cu-PTFE (Fig. 2 , c iii) samples by an ITO electrode, before the electrode is separated a distance of 5mm at a speed of ~ 100 mm s − 1 . The pristine PTFE film generated a peak-to-peak short-circuit current of 50 nA arising from the natural triboelectrification of PTFE in contact with ITO. However, the Cu-PTFE film produced over 1500 nA of current, corresponding to a 30-fold improvement in electromechanical harvesting compared to the pristine PTFE sample. The asymmetric electric signals observed from triboelectric mode testing (Fig. 2 , c ii-iii) occur due to the variations in the speed of the electrode motion during contact and separation steps, as indicated in the experimental section. Interestingly, Cu-PTFE in non-contact mode testing produces a nearly equivalent short-circuit current (37 nA) to PTFE in triboelectric mode testing (50 nA), highlighting the extreme improvement in electromechanical performance from Cu + implantation. This comparative improvement was also observed when the voltage curves in non-contact mode (Cu-PTFE only, Fig. 3 , a) and triboelectric mode testing (Cu-PTFE and PTFE, Fig. 3 , b-c) with a peak-to-peak voltage of non-contact tested Cu-PTFE of 50V at 10 GΩ increased to 310 V at 10 GΩ in triboelectric mode testing. However, the non-contact tested Cu-PTFE voltage was more than double that of the triboelectric pristine PTFE voltage of 11 V. The resultant energy and power density of the Cu-PTFE film (Fig. 3 , d-e) in non-contact mode testing and triboelectric testing respectively were calculated as 12 nJ cm − 2 and 30 nW cm − 2 (non-contact) and 1.4 µJ cm − 2 and 24 µW cm − 2 (triboelectric mode) able to power small scale IoT devices. 7 While the enhancement of TENG performance from ion implantation has been observed previously, as stated above, the role of space charge and subsequent induction of this space charge on TENG electrodes has been neglected. Even without an externally applied voltage, the space charge generated by ion implantation is expected to be proportional to the number of donors and the static dielectric constant. For extremely low frequencies ion implantation enhances the real dielectric coefficient due to the fractal behaviour of the collision cascade. 71 Outlook: Space Charge and Mechanisms Here, we demonstrate that this space charge is significant enough to induce a piezoelectric-like dipole within a PTFE film, and thus achieve improved TENG performance through hybrid P-TENG principles (Fig. 4 ). The consideration of these ion implanted polymers as P-TENGs explains why some polymers do not see an improved triboelectrification after ion implantation, where the direction of the piezoelectric-like dipole is in opposition to the triboelectric charge of the polymer itself. In pristine PTFE, minimal electromechanical response is observed during approach and compression stages of triboelectric testing, due to the lack of space charge in the structure, and triboelectrification occurs due to typical charge transfer across the interface (Fig. 4 , a). In contrast, for Cu-PTFE the approach and compression phases of triboelectric testing do produce electromechanical output, however the primary enhancement in triboelectric performance arises from the piezoelectric field-triboelectric coupling phenomenon driving enhanced charge separation (Fig. 4 , b). Conclusions Ion implantation of polymers is a relatively unexplored tool to produce electromechanical conversion materials. The implantation of 1 x 10 16 ions Cu cm − 2 resulted in a material with embedded space charge, able to induce current flow in a nearby moving electrode, and also demonstrating a weak piezoelectric-like effect. The space charge and subsequent electric field-triboelectric interfacial coupling led to an enhancement in the triboelectrification of Cu-PTFE with ITO of 30 x. These first investigation on non-contact and piezoelectric electromechanical conversion from ion implanted polymer films enable a clear assessment of the enhancement mechanisms for ion implanted polymer-based TENGs, with guiding principles based on hybrid P-TENG systems (that is, using additive dipole directions rather than opposing), being able to be adopted broadly for study in the future. Methods Ion Implantation of Cu on PTFE Ion implantation was performed using a Penning sputter ion source. 53 , 54 Cu was implanted into 50 µm thick PTFE to a fluence of 1×10 16 at.cm − 2 with an acceleration potential of 20 keV. A raster-scanner ensures homogeneous implantation into the substrate of the implanted area with a size of 13 mm × 13 mm. During implantation carbon tape the PTFE surface is contacted to the sample holder stage with conductive tape to minimise charging of the sample. To limit potential heating the current density is limited to 1 µA cm − 2 . Monte-carlo simulation to evaluate the ion-beam – polymer interaction were performed using the program SDTRIM.SP version 5.07. 55 The simulation use a Krypton – Carbon (KrC) potential with surface binding energies of 3.49 eV, 4.79 eV and 0.82 eV for Cu, C and F, respectively. The calculations are based on a substrate density of 2.2 gcm − 3 . The changes of the implanted area are taken into dynamic consideration to analyse the change of the implanted area such as surface sputtering of the already implanted Cu. Electromechanical Testing Electromechanical response in non-contact mode, piezoelectric mode and contact-separation mode was measured under controlled testing conditions using an Instron E1000 material testing machine. In non-contact mode , ITO electrode plates with an area of 6.25 cm 2 were oscillated in the distance between 0.1 mm to 1.1 mm. In piezoelectric mode , sample films were compressed and released in a range from 0 N to 10 N. The sample film was fixed between ITO electrodes by conductive double adhesive tape to eliminate other parasitic triboelectric signals from friction. 36 , 51 In triboelectric mode, the films were contacted with ITO by 10N force and separated at a distance of 5 mm with a separation speed of 0.1 m s − 1 . All triboelectric measurements were carried out at 22°C and humidity 45% RH. For electrical measurements , the generated current and voltage signals were recoded by Keithley 6514 electrometer connected to a Picoscope 5444B PC oscilloscope system. The surface charge, Q (nC), was calculated from the measured current peaks using the equation Q = ∫idt, where i is the instantaneous current (nA) and dt is the differential of time (s). Declarations Acknowledgements PCS would like to acknowledge support from RMIT University via the RMIT Vice-Chancellor’s Fellowship Scheme (2023). AS, HF, and PCS would like to acknowledge support from Catalyst: Seeding funding provided by the New Zealand MBIE and administrated by the Royal Society Te Aparangi (CSG-GNS2303). The authors acknowledge the facilities, and the scientific and technical assistance of the RMIT University’s Microscopy & Microanalysis Facility (RMMF), a linked laboratory of the Microscopy Australia, enabled by NCRIS. HF acknowledges funding from the New Zealand Ministry of Business Innovation and Employment Low Carbon Future programme (Strategic Science Investment Fund, Grant Number: C05X1702). The authors are grateful for access to and technical assistance associated with the use of the equipment and facilities in the RMIT School of Science and RMMF, particularly Dr Billy Murdoch. References Kepler RG, Anderson R (1992) Ferroelectric polymers. Adv Phys 41:1–57 Shepelin NA et al (2019) New developments in composites, copolymer technologies and processing techniques for flexible fluoropolymer piezoelectric generators for efficient energy harvesting. Energy Environ Sci 12:1143–1176. https://doi.org:10.1039/C8EE03006E Marvan M, Havránek A in Chudáček, I. (eds) Relationships of Polymeric Structure and Properties. Progress in Colloid & Polymer Science, vol 78 Relationships of Polymeric Structure and Properties 33–36 (Steinkopff, 1988) Huang S et al (2018) Flexoelectricity in dielectrics: Materials, structures and characterizations. J Adv Dielectr 08:1830002. https://doi.org:10.1142/S2010135X18300025 Zhang Y et al (2019) Ferroelectret materials and devices for energy harvesting applications. Nano Energy 57:118–140. https://doi.org:https:/ /doi.org/10.1016/j.nanoen.2018.12.040 Fan F-R, Tian Z-Q, Wang ZL (2012) Flexible triboelectric generator. Nano energy 1:328–334 Šutka A et al (2023) Engineering Polymer Interfaces: A Review toward Controlling Triboelectric Surface Charge. Adv Mater Interfaces 10:2300323. https://doi.org:https://doi.org/10.1002/admi.202300323 Sherrell PC, Sutka A, Timusk M, Sutka A (2024) Alternatives to Fluoropolymers for Motion-based Energy Harvesting: Perspectives on Piezoelectricity, Triboelectricity, Ferroelectrets, and Flexoelectricity. Small https://doi.org:10.1002/smll.202311570 Sherrell PC et al (2021) Probing Contact Electrification: A Cohesively Sticky Problem. ACS Appl Mater Interfaces 13:44935–44947. https://doi.org:10.1021/acsami.1c13100 Li S et al Contributions of Different Functional Groups to Contact Electrification of Polymers. Adv Mater n/a, 2001307 https://doi.org:10.1002/adma.202001307 Liu Y, Liu G, Bu T, Zhang C (2021) Effects of interfacial acid–base on the performance of contact–separation mode triboelectric nanogenerator. Mater Today Energy 20:100686. https://doi.org:https://doi.org/10.1016/j.mtener.2021.100686 Li S et al (2020) Contributions of Different Functional Groups to Contact Electrification of Polymers. Adv Mater 32:2001307. https://doi.org:https://doi.org/10.1002/adma.202001307 Šutka A et al (2019) The role of intermolecular forces in contact electrification on polymer surfaces and triboelectric nanogenerators. Energy Environ Sci 12:2417–2421 Kim DW, Lee JH, Kim JK, Jeong U (2020) Material aspects of triboelectric energy generation and sensors. NPG Asia Mater 12:6. https://doi.org:10.1038/s41427-019-0176-0 Verners O et al (2022) Smooth polymers charge negatively: Controlling contact electrification polarity in polymers. Nano Energy 104:107914 Persson BNJ (2020) On the role of flexoelectricity in triboelectricity for randomly rough surfaces. EPL (Europhysics Letters) 129:10006. https://doi.org:10.1209/0295-5075/129/10006 Lapčinskis L et al (2021) Triboelectrification of nanocomposites using identical polymer matrixes with different concentrations of nanoparticle fillers. J Mater Chem A 9:8984–8990. https://doi.org:10.1039/D0TA12441A Zhang J et al (2021) Recent developments of hybrid piezo–triboelectric nanogenerators for flexible sensors and energy harvesters. Nanoscale Adv 3:5465–5486. https://doi.org:10.1039/D1NA00501D Xu C et al (2018) On the Electron-Transfer Mechanism in the Contact-Electrification Effect. Adv Mater 30:1706790. https://doi.org:https://doi.org/10.1002/adma.201706790 Wang ZL, Wang AC (2019) On the origin of contact-electrification. Mater Today 30:34–51. https://doi.org https://doi.org/10.1016/j.mattod.2019.05.016 Verners O, Lapčinskis L, Sherrell PC, Šutka A (2023) Contact Electrification at Dielectric Polymer Interfaces: On Bond Scission, Material Transfer, and Electron Transfer. Adv Mater Interfaces 10:2300562. https://doi.org:https://doi.org/10.1002/admi.202300562 McCarty LS, Whitesides GM (2008) Electrostatic Charging Due to Separation of Ions at Interfaces: Contact Electrification of Ionic Electrets. Angew Chem Int Ed 47:2188–2207. https://doi.org:https://doi.org/10.1002/anie.200701812 Fang Y et al (1986) (2024) Static charge is an ionic molecular fragment. Nature Communications 15, https://doi.org:10.1038/s41467-024-46200-3 Im S, Frey E, Lacks DJ, Genzer J, Dickey MD Enhanced Triboelectric Charge Stability by Air-Stable Radicals. Adv Sci n/a, 2304459 https://doi.org:https://doi.org/10.1002/advs.202304459 Šutka A et al (2018) Triboelectric nanogenerator based on immersion precipitation derived highly porous ethyl cellulose. J Electrostat 92:1–5. https://doi.org https://doi.org/10.1016/j.elstat.2018.01.003 Lapčinskis L et al (2021) Triboelectrification of nanocomposites using identical polymer matrixes with different concentrations of nanoparticle fillers. J Mater Chem A 9:8984–8990 Lapčinskis L et al (2024) Controlling the magnitude and polarity of surface charges in PEBA polymers by adding UIO-66 MOFs. Mater Adv 5:4242–4250. https://doi.org:10.1039/D3MA01172K Lapčinskis L et al (2020) The Adhesion-Enhanced Contact Electrification and Efficiency of Triboelectric Nanogenerators. Macromol Mater Eng 305:1900638. https://doi.org:https://doi.org/10.1002/mame.201900638 Šutka A et al (2019) The role of intermolecular forces in contact electrification on polymer surfaces and triboelectric nanogenerators. Energy Environ Sci 12:2417–2421. https://doi.org:10.1039/C9EE01078E Li S et al (2020) Manipulating the triboelectric surface charge density of polymers by low-energy helium ion irradiation/implantation. Energy Environ Sci 13:896–907. https://doi.org:10.1039/C9EE03307F Fan Y et al (2021) Negative triboelectric polymers with ultrahigh charge density induced by ion implantation. Nano Energy 90:106574. https://doi.org https://doi.org/10.1016/j.nanoen.2021.106574 Pandey RK, Kakehashi H, Nakanishi H, Soh S (2018) Correlating Material Transfer and Charge Transfer in Contact Electrification. J Phys Chem C 122:16154–16160. https://doi.org:10.1021/acs.jpcc.8b04357 Bai P et al (2014) Dipole-moment-induced effect on contact electrification for triboelectric nanogenerators. Nano Res 7:990–997. https://doi.org:10.1007/s12274-014-0461-8 Akbarinejad A et al (2024) Stretching, Tapping, or Compressing–What Role Does Triboelectricity Play in the Signal Output from Piezoelectric Nanogenerators? Adv Electron Mater 10:2400019. https://doi.org:https://doi.org/10.1002/aelm.202400019 Leon RT et al (2024) Understanding and Controlling Electrostatic Discharge in Triboelectric Nanogenerators. ChemSusChem 17, e202400366 https://doi.org:https:// doi.org/10.1002/cssc.202400366 Leon RT, Sherrell PC, Šutka A, Ellis AV (2023) Decoupling piezoelectric and triboelectric signals from PENGs using the fast fourier transform. Nano Energy 110:108445. https://doi.org:https://doi.org/10.1016/j.nanoen.2023.108445 Leveneur J et al (2023) Surface modification of collagen using low-energy noble gas ion implantation. Surf Coat Technol 468:129768. https://doi.org/10.1016/j.surfcoat.2023.129768 . https://doi.org: Sobolev YI, Adamkiewicz W, Siek M, Grzybowski BA (2022) Charge mosaics on contact-electrified dielectrics result from polarity-inverting discharges. Nat Phys. https://doi.org:10.1038/s41567-022-01714-9 Baytekin HT, Baytekin B, Incorvati JT, Grzybowski BA (2012) Material Transfer and Polarity Reversal in Contact Charging. Angew Chem Int Ed 51:4843–4847. https://doi.org:https://doi.org/10.1002/anie.201200057 Baytekin HT et al (2011) The Mosaic of Surface Charge in Contact Electrification. Science 333:308–312. https://doi.org:doi:10.1126/science.1201512 Mizzi CA, Lin AYW, Marks LD (2019) Does Flexoelectricity Drive Triboelectricity? Phys Rev Lett 123:116103. https://doi.org:10.1103/PhysRevLett.123.116103 Marks LD, Olson KP, Flexoelectricity Triboelectricity, and Free Interfacial Charges. Small n/a, 2310546 https://doi.org:https://doi.org/10.1002/smll.202310546 Olson KP, Marks LD (2024) What Puts the Tribo in Triboelectricity? Nano Lett 24:12299–12306. https://doi.org:10.1021/acs.nanolett.4c03656 Malone N et al (2024) Grain Boundary-Rich Tungsten Carbide Nanoparticle Films Exhibit High Intrinsic Activity Toward Hydrogen Evolution. ACS Appl Nano Mater. https://doi.org:10.1021/acsanm.3c05497 Malone N et al (2023) High Turnover Frequency for the Hydrogen Evolution Reaction on Molybdenum Carbide Thin Films Synthesized by Ion Implantation. ACS Appl Eng Mater 1:2377–2385. https://doi.org:10.1021/acsaenm.3c00298 Fiedler H et al (2023) Room Temperature Ion Beam Synthesis of Ultra-Fine Molybdenum Carbide Nanoparticles: Toward a Scalable Fabrication Route for Earth-Abundant Electrodes. Small https://doi.org:10.1002/smll.202304118 Fiedler H et al (2021) Tuning the electromechanical properties and polarization of Aluminium Nitride by ion beam-induced point defects. Acta Mater 203 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096842196&doi=10.1016%2fj.actamat.2020.116495&partnerID=40&md5=7ba580396f719d1710ac0e49b49372ef Fiedler H et al (2021) Giant Piezoelectricity of Deformed Aluminium Nitride Stabilised through Noble Gas Interstitials for Energy Efficient Resonators. Adv Electron Mater 7:2100358. https://doi.org:10.1002/aelm.202100358 Booth MA, Leveneur J, Costa AS, Kennedy J, Travas-Sejdic J (2012) Tailoring the Conductivity of Polypyrrole Films Using Low-Energy Platinum Ion Implantation. J Phys Chem C 116:8236–8242. https://doi.org:10.1021/jp300682q Šutka A et al (2023) High-Performance Hybrid Triboelectric Generators Based on an Inversely Polarized Ultrahigh β-Phase PVDF. ACS Appl Energy Mater 6:9300–9306. https://doi.org:10.1021/acsaem.3c01196 Šutka A et al (2020) Measuring Piezoelectric Output—Fact or Friction? Adv Mater 32:2002979. https://doi.org:10.1002/adma.202002979 Lees EW, Mowbray BA, Parlane FG, Berlinguette CP (2022) Gas diffusion electrodes and membranes for CO2 reduction electrolysers. Nat Reviews Mater 7:55–64 Fiedler H, Gupta P, Kennedy J, Markwitz A (2018) 28Si + ion beams from Penning ion source based implanter systems for near-surface isotopic purification of silicon. Rev Sci Instrum 89. https://doi.org:10.1063/1.5048949 Fiedler H et al (2024) Room Temperature Ion Beam Synthesis of Ultra-Fine Molybdenum Carbide Nanoparticles: Toward a Scalable Fabrication Route for Earth-Abundant Electrodes. Small 20:2304118. https://doi.org:https://doi.org/10.1002/smll.202304118 Mutzke A, Schneider R, Eckstein W, Dohmen R, SDTrimSP (2011) Version 5.00. ipp, report,(12/8). Max Planck-Institut fr Plasmaphysik Kawai H (1969) The Piezoelectricity of Poly (vinylidene Fluoride). Jpn J Appl Phys 8:975. https://doi.org:10.1143/JJAP.8.975 Šutka A et al (2018) Inversely polarised ferroelectric polymer contact electrodes for triboelectric-like generators from identical materials. Energy Environ Sci 11:1437–1443. https://doi.org:10.1039/C8EE00550H Sherrell PC et al (2022) A bright future for engineering piezoelectric 2D crystals. Chem Soc Rev 51:650–671. https://doi.org:10.1039/D1CS00844G Habib M, Lantgios I, Hornbostel K (2022) A review of ceramic, polymer and composite piezoelectric materials. J Phys D: Appl Phys 55:423002 Šutka A et al (2024) Recycled Polystyrene Waste to Triboelectric Nanogenerators: Volumetric Electromechanically Responsive Laminates from Same Material Contact Electrification. Adv Energy Sustain Res. https://doi.org:10.1002/aesr.202300259 Linarts A, Sherrell PC, Mālnieks K, Ellis AV, Šutka A (2023) Electrospinning Triboelectric Laminates: A Pathway for Scaling Energy Harvesters. Small 19:2205563. https://doi.org:https://doi.org/10.1002/smll.202205563 Zhang LA et al (2023) Collecting the space-distributed Maxwell's displacement current for ultrahigh electrical density of TENG through a 3D fractal structure design. Energy Environ Sci 16:3781–3791 Zhang X, Pondrom P, Sessler GM, Ma X (2018) Ferroelectret nanogenerator with large transverse piezoelectric activity. Nano Energy 50:52–61. https://doi.org/10.1016/j.nanoen.2018.05.016 . https://doi.org: Ghosh SK, Sinha TK, Mahanty B, Mandal D (2015) Self-poled efficient flexible Ferroelectretic nanogenerator: a new class of piezoelectric energy harvester. Energy Technol 3:1190–1197 Zhang X, Zhang X, Sessler GM, Gong X in 2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena. 579–582 Simon Ž, Dharmasiri B, Harte T, Sherrell PC, Henderson LC (2024) From stress to charge: investigating the piezoelectric response of solvate ionic liquid in structural energy storage composites. Mater Horiz 11:4321–4328. https://doi.org:10.1039/D4MH00612G Patnam H, Dudem B, Graham SA, Yu JS (2021) High-performance and robust triboelectric nanogenerators based on optimal microstructured poly(vinyl alcohol) and poly(vinylidene fluoride) polymers for self-powered electronic applications. Energy 223:120031. https://doi.org:https://doi.org/10.1016/j.energy.2021.120031 Pang Y et al (2021) Hybrid Energy-Harvesting Systems Based on Triboelectric Nanogenerators. Matter 4:116–143. https://doi.org:https:// doi.org/10.1016/j.matt.2020.10.018 Zhao C et al (2019) Hybrid piezo/triboelectric nanogenerator for highly efficient and stable rotation energy harvesting. Nano Energy 57:440–449. https://doi.org https://doi.org/10.1016/j.nanoen.2018.12.062 Han M, Chen X, Yu B, Zhang H (2015) Coupling of Piezoelectric and Triboelectric Effects: from Theoretical Analysis to Experimental Verification. Adv Electron Mater 1:1500187. https://doi.org:10.1002/aelm.201500187 Wasserman B (1986) Fractal nature of electrical conductivity in ion-implanted polymers. Physical Review B 34, 1926–1931 https://doi.org:10.1103/PhysRevB.34.1926 Additional Declarations There is NO Competing Interest. 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Also discoverable on Platform About Our Team In Review Editorial Policies Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5436005","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":381006169,"identity":"bcbbb93a-acf0-4470-a631-a861b1067f8c","order_by":0,"name":"Peter Sherrell","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABDklEQVRIiWNgGAWjYBCDBDD5oMCGgYEZxGLDp5gZSUuCQRpQgJk0LYehIni0mLP3H3xcwVCXxy999uGDBIPz+brt/AcYPpQdZuCfkYBVi2XPYWbDMwyHiyX70o0NEgxuW247zMzAOOPcYQaJG9i1GNxIZpNsYDiQuOEMG5sEUIuBGVALM28b0IW4tNx/zP6zgaEucf8ZNvYfCQbnIFr+ArXI47SFmY2xgYE5cQMPGxvQ+wcgWhiBWgxwaLHsSTaWbDA4nDjjDBsz0GHJIC0GB3vOpfMYnnmAI8QOPvzYUFGX2N/DxvjhQ4Wdgdn5gw8f/CizlpM7jsNhSCQCHABiHqzqsSgeBaNgFIyCUYAJAJyLWOQ372poAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0003-4644-6238","institution":"RMIT University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Peter","middleName":"","lastName":"Sherrell","suffix":""},{"id":381006170,"identity":"6670c17c-9c06-46dc-af1e-50849eb0fad6","order_by":1,"name":"Andris Šutka","email":"","orcid":"https://orcid.org/0000-0002-5739-0164","institution":"Riga Technical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Andris","middleName":"","lastName":"Šutka","suffix":""},{"id":381006171,"identity":"85cd0a6c-b9aa-473d-b1fb-f90eb870a591","order_by":2,"name":"Holger Fiedler","email":"","orcid":"","institution":"GNS Science","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Holger","middleName":"","lastName":"Fiedler","suffix":""},{"id":381006172,"identity":"de90f74a-6243-4d2c-ade5-d0eb8204164a","order_by":3,"name":"Artis Linarts","email":"","orcid":"","institution":"","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Artis","middleName":"","lastName":"Linarts","suffix":""},{"id":381006173,"identity":"7dd2c56b-c3f8-4140-9115-9f48f8ae6472","order_by":4,"name":"Kaspars Malnieks","email":"","orcid":"","institution":"Riga Technical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Kaspars","middleName":"","lastName":"Malnieks","suffix":""}],"badges":[],"createdAt":"2024-11-12 04:20:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5436005/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5436005/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1103/th79-cjz6","type":"published","date":"2026-02-06T00:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":69794030,"identity":"afe7107c-b53b-4160-8abe-b73e45153606","added_by":"auto","created_at":"2024-11-25 10:04:50","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":515038,"visible":true,"origin":"","legend":"\u003cp\u003ea)\u003cstrong\u003e \u003c/strong\u003eSchematic of Ion Implantation Methodology; b)\u003cstrong\u003e \u003c/strong\u003eSimulated Ion implantation depth for Copper in PTFE (right panel shows the depth over the 0.05 mm thickness of PTFE); and c) 1 x 10\u003csup\u003e16\u003c/sup\u003e ions Cu cm\u003csup\u003e-2\u003c/sup\u003e sample, showing the implantation area of 13 mm x 13mm.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-5436005/v1/64562f124d2b91e7ccc211db.png"},{"id":69791594,"identity":"31c3744a-cc91-413e-ba21-6dcd529dee66","added_by":"auto","created_at":"2024-11-25 09:48:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":119109,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of electromechanical conversion in a) non-contact mode; b) piezoelectric mode; and c) triboelectric mode) (i) schematic; for ii) pristine PTFE compared to iii) 1 x 10\u003csup\u003e16\u003c/sup\u003e Cu implanted PTFE.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-5436005/v1/714eaaab46e8659b189040da.png"},{"id":69791593,"identity":"88305148-50d8-4b69-882d-5cc34e065361","added_by":"auto","created_at":"2024-11-25 09:48:50","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":203001,"visible":true,"origin":"","legend":"\u003cp\u003eVoltage outputs under load resistances ranging from 10 MΩ to 10 GΩ for; a) non-contact mode for 1 x 10\u003csup\u003e16\u003c/sup\u003e Cu-PTFE, b) triboelectric mode 1 x 10\u003csup\u003e16\u003c/sup\u003e Cu-PTFE; c) triboelectric mode for pristine PTFE (note, non-contact PTFE is not shown as no voltage was measured); and d) energy density and e) power density for non-contact and triboelectric mode 1 x 10\u003csup\u003e16\u003c/sup\u003e Cu-PTFE.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-5436005/v1/c462adeddbc408c796f007a7.png"},{"id":69791261,"identity":"5cd3c602-6b17-4704-8f60-58f2cd66e826","added_by":"auto","created_at":"2024-11-25 09:40:50","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":86265,"visible":true,"origin":"","legend":"\u003cp\u003ePhenomenon occurring during triboelectric mode testing of a) PTFE; and b) Cu-PTFE. In the Cu-PTFE case, electromechanical conversion occurs during all stages of triboelectric testing, however the magnitude of non-contact induction and piezoelectric-like response is significantly smaller than the space charge induced coupling to triboelectric charge separation.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-5436005/v1/d9fac86ffcb8ff2c08869318.png"},{"id":109272576,"identity":"88507f07-aa89-484a-9e1a-51bd84c02784","added_by":"auto","created_at":"2026-05-14 14:14:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1129527,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5436005/v1/461cd040-aa2c-4ee2-a9ac-10ab4fe4114d.pdf"},{"id":69791258,"identity":"3b00a52d-ace4-4aa5-a5e5-e9532178fbeb","added_by":"auto","created_at":"2024-11-25 09:40:50","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":119642,"visible":true,"origin":"","legend":"","description":"","filename":"Supplmentary.docx","url":"https://assets-eu.researchsquare.com/files/rs-5436005/v1/aa07a6fe5654919724ef6a58.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Space charge drives electromechanical conversion via a piezoelectric-like effect in ion implanted polymers","fulltext":[{"header":"Introduction","content":"\u003cp\u003eFlexible, polymeric, materials that convert kinetic energy into electricity (or electrical charge) are attracting immense research interest from applications ranging from powering internet-of-things (IoT) microdevices to wearable sensors to enabling green chemical transformations. Materials can achieve this through several phenomena, including ferroelectricity,\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e piezoelectricity,\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e flexoelectricity,\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e porous electrets,\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e or contact-electrification or triboelectricity.\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e Of these phenomena, triboelectricity provides key advantages over other electromechanical conversion phenomenon, as it does not require specific materials to generate charge rather the occurrence of consistent interfacial friction.\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e In particular for triboelectricity, fluoropolymers which are the most common piezoelectric and ferroelectric polymer family, can be avoided.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eTriboelectricity is exploited through the fabrication of the triboelectric nanogenerator (TENG), whereby two dissimilar (in terms of surface chemistry,\u003csup\u003e\u003cspan additionalcitationids=\"CR10 CR11\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e mechanical properties,\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e topography,\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e or additives\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e)\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e undergo cyclic friction, with the produced surface charge causing a Maxwells displacement current to flow on nearby electrodes.\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e While the fundamental mechanism of TENGs remains the subject of debate in literature (between electron transfer,\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e and ionic or molecular fragments\u003csup\u003e\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e), significant focus has been devoted to increasing the amount of energy a TENG can produce \u003cem\u003evia\u003c/em\u003e directly increasing (and stabilizing\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e) the surface charge produced at the contact interface.\u003c/p\u003e \u003cp\u003eTo increase the surface charge, different approaches have been used, such as nanostructuring ,\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e adding fillers \u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e increasing adhesion, modifying mechanical properties, \u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e,\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e or recently ion- implantation.\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e Ion implantation provides a key capability to enhance the surface charge or arbitrary materials. This broad use case makes ion implantation a particularly attractive, yet relatively unstudied approach with recent reports should an 8x enhancement compared to equivalent pristine polymers simply be depositing 1 x 10\u003csup\u003e16\u003c/sup\u003e He ions cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e,\u003csup\u003e31\u003c/sup\u003e up to a surface charge density of 332 \u0026micro;C m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.\u003csup\u003e30\u003c/sup\u003e However, in this case the supposed advantage of ion implantation (to enhance arbitrary materials) failed, and only Kapton (polyimide) showed an enhancement, while other commonly used triboelectric materials including polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and fluorinated ethylene propylene (FEP) only showed a minor or no enhancement in surface charge.\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eDespite this effect, the enhancement in surface charge observed by Li et al., was immense (far outstripping the maximum surface charge achieved through manipulating adhesion, morphology, fillers, mechanical properties, or ferroelectric films (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of surface charge density measured in triboelectric testing achieved by manipulating specific factors.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSurface charge modification method\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCharge measured\u003c/p\u003e \u003cp\u003e(\u0026micro;C m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEnhancement\u003c/p\u003e \u003cp\u003e(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRef(s)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eAdhesion\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003csup\u003e\u0026dagger;\u003c/sup\u003e 37x\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eFiller\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.5x\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eMechanical Properties\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20 x\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eIon implantation\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e332 Aptos (Body)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8x\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eFerroelectric films\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e353\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2x\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e* The authors note that variations in testing methods leads to a significant alteration in measured charge,\u003csup\u003e\u003cspan additionalcitationids=\"CR35\" citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e however this charge can still provide a simple comparison tool \u0026ndash; and the use of enhancement % enables comparison within a references own data.\u003c/p\u003e \u003cp\u003e\u0026dagger; Surface chemistry of the contact interface was also changed\u003c/p\u003e \u003cp\u003eThe enhancement in surface charge from io beam implantation has been attributed to enhanced electron transfer due to changes in macromolecular processes, such as breaking the chemical chain of the polymer and free radical combination to form new chemical bonds and chemical group.\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. Ion implantation, without a doubt, will alter the molecular structure and chemistry of the polymers, and is clearly observed in Raman spectroscopy and Fourier transform infra-red (FTIR) spectroscopy. \u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e,\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e However, such an effect cannot explain why the polarity inversion of Kapton in contact with Aluminium foil after implantation. The maximum charge measured for polarised ferroelectric films of 353 \u0026micro;C m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e,\u003csup\u003e33\u003c/sup\u003e is extremely similar to the charge density measured by ion implantation of 332 \u0026micro;C m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e,\u003csup\u003e30\u003c/sup\u003e this correlation does not indicate causation but does show the magnitude of the ion implantation effect. In ferroelectric polymers, triboelectric charge enhancement comes from the coupling of the electric field from the polarisation within the polymer film with the triboelectric charge transfer \u0026ndash; producing an order of magnitude more surface charge than other techniques alone.\u003csup\u003e\u003cspan additionalcitationids=\"CR39 CR40 CR41 CR42\" citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e In contrast, ion implanted polymers have been reported to increase the surface charge density due to bond breakage and ionic charges enabled enhanced electron transfer, rather than coupling to existing triboelectric charge transfer mechanisms (including ion and mass transfer). \u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIon implantation as a general technique has received significant studies focussed on implantation into ceramics, whereby the implanted ion displaces the ceramic lattice and creating defects, strain (via occupancy of interstitial sites), or substituting with lattice atoms.\u003csup\u003e\u003cspan additionalcitationids=\"CR45 CR46 CR47\" citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e However, these phenomenon occur very differently in polymers, which typically possess a significantly lower atomic packing density, are flexible and whose 1D-covalent bonding network enables chain rotation. While the binary elastic collision approximation remains valid, interpretation of the substrate-ion beam interaction alters dramatically. This alteration arises as; a) the flexibility of the polymer enables a higher number of charged interstitial/or void space occupancy sites; and b) the displacement of covalently bonded atoms due to the high ion energy motion causes displacement of the polymer chains the formation of a large number of vacancy-like sites.\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e,\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e Given the high dielectric nature of polymers, preventing electron flow from the drain during implantation into the polymer, even if the charge on these ions are compensated, a net charge within the polymer may be generated.\u003c/p\u003e \u003cp\u003eThe 1D nature of polymer chains, suggests that ion impacts into the polymer backbone can result in side-group loss from the polymer chain, creating volatile products and partial graphitisation (sp\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e bond formation) of the polymer backbone.\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e In addition, ion implantation can also remove surface defects and contamination, especially for low energy implantation conditions.\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eHere, we demonstrate that the enhanced triboelectric performance of ion-implanted PTFE is simply due to the introduction of these charged ions into the polymer matrix, creating a space charge effect after implantation. Implanting PTFE with 1 x 10\u003csup\u003e16\u003c/sup\u003e Cu\u003csup\u003e+\u003c/sup\u003e ions cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e results in a material which creates significant Maxwells displacement current during motion near a parallel plate. The presence of this space charge, thus makes the implanted PTFE act as a piezoelectric material, providing an external electric field mimicking the enhancement of TENGs using hybrid piezoelectric-TENGs.\u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e We demonstrate that this space charge leads to a 28.9 fold improvement in TENG mode testing of implanted PTFE against an Indium Tin Oxide (ITO) electrode proving a tool to significantly enhance electromechanical conversion within polymers for energy harvesting and sensing applications.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eIon Implantation\u003c/h2\u003e \u003cp\u003eTo investigate the function of ion implantation into polymers for TENGs, a simple experiment was conceived whereby ion implanted polymers were subjected to traditional electromechanical testing processes in piezoelectric mode (oscillatory compression without breaking contact), non-contact oscillation near a metal plate, and triboelectric \u0026lsquo;contact-separation mode).\u003csup\u003e\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e In order to gain relevant results, from triboelectric testing Cu\u003csup\u003e+\u003c/sup\u003e was chosen for ion implantation as it is a multivalent cation with a relatively high charge density, whist being known to have extremely limited passive diffusion through PTFE. \u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eCu\u003csup\u003e+\u003c/sup\u003e was implanted into PTFE via a Penning sputter ion source at a fluence of 1 x 10\u003csup\u003e16\u003c/sup\u003e ions cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e with an acceleration potential of 20 keV (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, a).\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e,\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e To ensure homogenous implantation across the target area of 13 mm x 13 mm, a raster scanning pattern was used along with a charge counter to precisely monitor deposited charge. The phenomenon occurring during ion implantation are schematically shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, a. To understand the depth and distribution of the implanted Cu\u003csup\u003e+\u003c/sup\u003e ions, monte-carlo simulations were performed to model the ion beam-polymer interactions using SDTRIP.SP version 5.07 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, b).\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e The simulations use a Krypton-Carbon potential with surface binding energies of 3.49 eV, 4.79 eV and 0.82 eV for Cu, C, and F respectively. These simulations show that for the fluence of 1 x 10\u003csup\u003e16\u003c/sup\u003e ions cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e the maximum Cu\u003csup\u003e+\u003c/sup\u003e implantation depth occurs at 240 \u0026Aring;, with an atomic concentration of Cu\u003csup\u003e+\u003c/sup\u003e reaching 10\u003csup\u003e\u0026minus;\u0026thinsp;21\u003c/sup\u003e(corresponding to 1 Cu\u003csup\u003e+\u003c/sup\u003e atom for every\u0026thinsp;~\u0026thinsp;330 C atoms). This high loading of ion implantation results in a discolouration of the clear PTFE, creating a dull brown (copper) colouration across the 13 mm x 13 mm implantation area (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, c). This discolouration may arise from either the copper itself or mild graphitization of the PTFE. Crucially, the simulations show that within 40 \u0026Aring; of the surface, the Cu\u003csup\u003e+\u003c/sup\u003e atomic concentration drops to 10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, b). This atomic concentration correlates to approximately 1 Cu\u003csup\u003e+\u003c/sup\u003e atoms for every 3 x 10\u003csup\u003e5\u003c/sup\u003e carbon atoms \u0026ndash; meaning there are very few Cu\u003csup\u003e+\u003c/sup\u003e atoms able near the surface of the PTFE film. These atoms are expected to be stable within the PTFE matrix, as PTFE is known to prevent ion migration through its films, and has been studied as a gas diffusion layer under a Cu catalyst extensively for CO\u003csub\u003e2\u003c/sub\u003e reduction, with no Cu diffusion being reported through the films.\u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e In ceramics, ion beam induced interstitials can change the polarisation of ceramics through deformation of the crystal lattice,\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e,\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e which is expected to be even more pronounced within soft polymer chains. Indeed, for PTFE and PVDF mechanical stretching at elevated temperature is sufficient to cause piezoelectric alignment of a polymer chain \u0026ndash; although the authors note there is no dipole moment across the polymer backbone to make PTFE piezoelectric.\u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e In contrast to pure mechanical stretching for PTFE,\u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e the piezoelectric signal after ion implantation is persistent for months, suggesting a semi-permanent dipole formation within the PTFE films.\u003c/p\u003e \u003cp\u003eGiven a large fraction of implanted Cu are expected to retain their charge post implantation, along with the depth profile of implanted Cu, a space charge region is formed within the PTFE, focussed between 100 \u0026Aring; and 500 \u0026Aring; into the 0.05 mm thick PTFE film. The localisation of space charge is expected to create an internal effective dipole, where the un-implanted back side of the PTFE possesses a relative neutral charge compared to the implanted side with a relative positive charge. The implantation of Cu\u003csup\u003e+\u003c/sup\u003e results in a discolouration of the PTFE in the implanted region (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, c), in line with the expected partial graphitization of the PTFE backbone.\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePrior reports have described the use of ion implantation to enhance the measured electromechanical conversion of a TENG. However, to the best of the authors knowledge, there are no reports probing how these ion implanted polymers behave as individual electromechanical materials.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eElectromechanical Response from Ion Implanted Polymers\u003c/h2\u003e \u003cp\u003eTo probe the presence of charge within the polymer film post Cu\u003csup\u003e+\u003c/sup\u003e implantation, non-contact oscillation (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, a i) of both the PTFE (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, ii) and Cu-PTFE (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, iii) films were performed relative to an ITO electrode. Here, the polymer films were oscillated from between 0.1 mm and 1.1 mm away from the ITO plate with the short circuit current being recorded. The pristine PTFE shows a negligible 0.2 nA peak-to-peak short circuit current due to the displacement relative to the ITO electrode displacement (Figure S1). In contrast, the Cu-PTFE film exhibits a stunning 185-fold increase in the non-contact current, achieving a peak-to-peak current of 37 nA. This result, aligns with the trend observed by Sutka et al.,\u003csup\u003e\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e\u003c/sup\u003e where poled ferroelectric poly(vinylidenedifluoride) (PVDF) were found to generate voltage in non-contact mode. These voltages arise due to electrostatic induction from a moving electric field, where the moving electric field corresponds to the permanent dipole within poled PVDF. With Cu-PTFE, the space charge region localised between 100 \u0026Aring; and 500 \u0026Aring; beneath the surface of the PTFE, creates the electric field to cause the measured electrostatic induction. The strength of the electric field generated by the space charge was demonstrated by x-ray photoelectron spectroscopy (Figure S2), with all peaks shifted to higher binding energies by more than 150 eV (C 1s, F 1s, Cu 2p) due to the presence of the positive Cu\u003csup\u003e+\u003c/sup\u003e ions hindering the ejection of electrons.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePiezoelectric-mode testing (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, b i), refers to the use of a pre-load force on the sample, to prevent any contact-separation events occurring, thus ensuring the lack of triboelectric effects when benchmarking piezoelectric materials.\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e,\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e Here, when a ΔF of 10N was applied to both the PTFE (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, b ii) and Cu-PTFE samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, b iii) minimal displacement was observed, indicating no contact-separation events were occurring. For the pristine film, 4 pA of short-circuit current was measured (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, b ii) which is considered negligible, and can arise due to stray electric fields or small friction events due to non-commensurate contact interfaces. In contrast, the Cu-PTFE demonstrated a considerable pseudo-piezoelectric effect with 40-fold increase in the peak-to-peak short-circuit current value to 165 pA (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, b iii). Given the lack of electrode displacement observed, this pseudo piezoelectric effect arises from the space charge region between 100 \u0026Aring; and 500 \u0026Aring; into the PTFE active as a positive region, with the neutrally charged bulk acting as a relatively negative region. Thus, compressing the Cu-PTFE moves the centre of charge of the Cu-PTFE creating induction analogous to piezoelectric compression testing. While this value of pseudo-piezoelectric effect is also smaller than reported for other piezoelectric materials,\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e,\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u003c/sup\u003e or piezoelectric-like material assemblies)\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan additionalcitationids=\"CR61 CR62 CR63 CR64\" citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e\u003c/sup\u003e it is higher than those measured during compression of highly charged ionic liquids or solid-polymer electrolytes.\u003csup\u003e\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e\u003c/sup\u003e The presence of this piezoelectric effect in Cu-PTFE suggests the ability to fabricate hybrid piezoelectric-TENGs (P-TENG) \u0026ndash; which have been often reported to demonstrate exceptional triboelectric performances, far outstripping standard TENG materials.\u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e,\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e,\u003cspan additionalcitationids=\"CR68 CR69\" citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e70\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eFinally, given the clear demonstration of 1) space charge within the Cu-PTFE via non-contact mode testing; and 2) a permeant dipole within Cu-PTFE giving rise to a pseudo-piezoelectric effect from piezoelectric-mode testing, contact-separation \u0026ldquo;triboelectric\u0026rdquo; testing was performed to evaluate the observed triboelectrification was performed (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, c i).\u003c/p\u003e \u003cp\u003eIn triboelectric testing mode, Δ5 N of force is applied to the PTFE (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, c ii) and Cu-PTFE (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, c iii) samples by an ITO electrode, before the electrode is separated a distance of 5mm at a speed of ~\u0026thinsp;100 mm s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The pristine PTFE film generated a peak-to-peak short-circuit current of 50 nA arising from the natural triboelectrification of PTFE in contact with ITO. However, the Cu-PTFE film produced over 1500 nA of current, corresponding to a 30-fold improvement in electromechanical harvesting compared to the pristine PTFE sample. The asymmetric electric signals observed from triboelectric mode testing (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, c ii-iii) occur due to the variations in the speed of the electrode motion during contact and separation steps, as indicated in the experimental section. Interestingly, Cu-PTFE in non-contact mode testing produces a nearly equivalent short-circuit current (37 nA) to PTFE in triboelectric mode testing (50 nA), highlighting the extreme improvement in electromechanical performance from Cu\u003csup\u003e+\u003c/sup\u003e implantation.\u003c/p\u003e \u003cp\u003eThis comparative improvement was also observed when the voltage curves in non-contact mode (Cu-PTFE only, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e3\u003c/span\u003e, a) and triboelectric mode testing (Cu-PTFE and PTFE, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e3\u003c/span\u003e, b-c) with a peak-to-peak voltage of non-contact tested Cu-PTFE of 50V at 10 GΩ increased to 310 V at 10 GΩ in triboelectric mode testing. However, the non-contact tested Cu-PTFE voltage was more than double that of the triboelectric pristine PTFE voltage of 11 V. The resultant energy and power density of the Cu-PTFE film (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e3\u003c/span\u003e, d-e) in non-contact mode testing and triboelectric testing respectively were calculated as 12 nJ cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and 30 nW cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e (non-contact) and 1.4 \u0026micro;J cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and 24 \u0026micro;W cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e (triboelectric mode) able to power small scale IoT devices.\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWhile the enhancement of TENG performance from ion implantation has been observed previously, as stated above, the role of space charge and subsequent induction of this space charge on TENG electrodes has been neglected. Even without an externally applied voltage, the space charge generated by ion implantation is expected to be proportional to the number of donors and the static dielectric constant. For extremely low frequencies ion implantation enhances the real dielectric coefficient due to the fractal behaviour of the collision cascade.\u003csup\u003e\u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e71\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eOutlook: Space Charge and Mechanisms\u003c/h2\u003e \u003cp\u003eHere, we demonstrate that this space charge is significant enough to induce a piezoelectric-like dipole within a PTFE film, and thus achieve improved TENG performance through hybrid P-TENG principles (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The consideration of these ion implanted polymers as P-TENGs explains why some polymers do not see an improved triboelectrification after ion implantation, where the direction of the piezoelectric-like dipole is in opposition to the triboelectric charge of the polymer itself. In pristine PTFE, minimal electromechanical response is observed during approach and compression stages of triboelectric testing, due to the lack of space charge in the structure, and triboelectrification occurs due to typical charge transfer across the interface (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e4\u003c/span\u003e, a). In contrast, for Cu-PTFE the approach and compression phases of triboelectric testing do produce electromechanical output, however the primary enhancement in triboelectric performance arises from the piezoelectric field-triboelectric coupling phenomenon driving enhanced charge separation (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e4\u003c/span\u003e, b).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIon implantation of polymers is a relatively unexplored tool to produce electromechanical conversion materials. The implantation of 1 x 10\u003csup\u003e16\u003c/sup\u003e ions Cu cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e resulted in a material with embedded space charge, able to induce current flow in a nearby moving electrode, and also demonstrating a weak piezoelectric-like effect. The space charge and subsequent electric field-triboelectric interfacial coupling led to an enhancement in the triboelectrification of Cu-PTFE with ITO of 30 x. These first investigation on non-contact and piezoelectric electromechanical conversion from ion implanted polymer films enable a clear assessment of the enhancement mechanisms for ion implanted polymer-based TENGs, with guiding principles based on hybrid P-TENG systems (that is, using additive dipole directions rather than opposing), being able to be adopted broadly for study in the future.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eIon Implantation of Cu on PTFE\u003c/h2\u003e \u003cp\u003eIon implantation was performed using a Penning sputter ion source. \u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e,\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e Cu was implanted into 50 \u0026micro;m thick PTFE to a fluence of 1\u0026times;10\u003csup\u003e16\u003c/sup\u003e at.cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e with an acceleration potential of 20 keV. A raster-scanner ensures homogeneous implantation into the substrate of the implanted area with a size of 13 mm \u0026times; 13 mm. During implantation carbon tape the PTFE surface is contacted to the sample holder stage with conductive tape to minimise charging of the sample. To limit potential heating the current density is limited to 1 \u0026micro;A cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eMonte-carlo simulation to evaluate the ion-beam \u0026ndash; polymer interaction were performed using the program SDTRIM.SP version 5.07. \u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e The simulation use a Krypton \u0026ndash; Carbon (KrC) potential with surface binding energies of 3.49 eV, 4.79 eV and 0.82 eV for Cu, C and F, respectively. The calculations are based on a substrate density of 2.2 gcm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e. The changes of the implanted area are taken into dynamic consideration to analyse the change of the implanted area such as surface sputtering of the already implanted Cu.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eElectromechanical Testing\u003c/h3\u003e\n\u003cp\u003eElectromechanical response in non-contact mode, piezoelectric mode and contact-separation mode was measured under controlled testing conditions using an Instron E1000 material testing machine.\u003c/p\u003e \u003cp\u003eIn \u003cem\u003enon-contact mode\u003c/em\u003e, ITO electrode plates with an area of 6.25 cm\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e were oscillated in the distance between 0.1 mm to 1.1 mm.\u003c/p\u003e \u003cp\u003eIn \u003cem\u003epiezoelectric mode\u003c/em\u003e, sample films were compressed and released in a range from 0 N to 10 N. The sample film was fixed between ITO electrodes by conductive double adhesive tape to eliminate other parasitic triboelectric signals from friction.\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e,\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIn \u003cem\u003etriboelectric\u003c/em\u003e mode, the films were contacted with ITO by 10N force and separated at a distance of 5 mm with a separation speed of 0.1 m s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. All triboelectric measurements were carried out at 22\u0026deg;C and humidity 45% RH.\u003c/p\u003e \u003cp\u003eFor \u003cem\u003eelectrical measurements\u003c/em\u003e, the generated current and voltage signals were recoded by Keithley 6514 electrometer connected to a Picoscope 5444B PC oscilloscope system. The surface charge, Q (nC), was calculated from the measured current peaks using the equation Q = \u0026int;idt, where i is the instantaneous current (nA) and dt is the differential of time (s).\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003ePCS would like to acknowledge support from RMIT University via the RMIT Vice-Chancellor\u0026rsquo;s Fellowship Scheme (2023). AS, HF, and PCS would like to acknowledge support from Catalyst: Seeding funding provided by the New Zealand MBIE and administrated by the Royal Society Te Aparangi (CSG-GNS2303). The authors acknowledge the facilities, and the scientific and technical assistance of the RMIT University\u0026rsquo;s Microscopy \u0026amp; Microanalysis Facility (RMMF), a linked laboratory of the Microscopy Australia, enabled by NCRIS. HF acknowledges funding from the New Zealand Ministry of Business Innovation and Employment Low Carbon Future programme (Strategic Science Investment Fund, Grant Number: C05X1702). The authors are grateful for access to and technical assistance associated with the use of the equipment and facilities in the RMIT School of Science and RMMF, particularly Dr Billy Murdoch.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKepler RG, Anderson R (1992) Ferroelectric polymers. Adv Phys 41:1\u0026ndash;57\u003c/li\u003e\n\u003cli\u003eShepelin NA et al (2019) New developments in composites, copolymer technologies and processing techniques for flexible fluoropolymer piezoelectric generators for efficient energy harvesting. Energy Environ Sci 12:1143\u0026ndash;1176. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1039/C8EE03006E\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eMarvan M, Havr\u0026aacute;nek A in \u003cem\u003eChud\u0026aacute;ček, I. (eds)\u003c/em\u003e Relationships of Polymeric Structure and Properties. Progress in Colloid \u0026amp; Polymer Science, vol 78 Relationships of Polymeric Structure and Properties 33\u0026ndash;36 (Steinkopff, 1988)\u003c/li\u003e\n\u003cli\u003eHuang S et al (2018) Flexoelectricity in dielectrics: Materials, structures and characterizations. J Adv Dielectr 08:1830002. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1142/S2010135X18300025\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eZhang Y et al (2019) Ferroelectret materials and devices for energy harvesting applications. Nano Energy 57:118\u0026ndash;140. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https:/\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e/doi.org/10.1016/j.nanoen.2018.12.040\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eFan F-R, Tian Z-Q, Wang ZL (2012) Flexible triboelectric generator. Nano energy 1:328\u0026ndash;334\u003c/li\u003e\n\u003cli\u003e\u0026Scaron;utka A et al (2023) Engineering Polymer Interfaces: A Review toward Controlling Triboelectric Surface Charge. Adv Mater Interfaces 10:2300323. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/admi.202300323\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eSherrell PC, Sutka A, Timusk M, Sutka A (2024) Alternatives to Fluoropolymers for Motion-based Energy Harvesting: Perspectives on Piezoelectricity, Triboelectricity, Ferroelectrets, and Flexoelectricity. \u003cem\u003eSmall\u003c/em\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/smll.202311570\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eSherrell PC et al (2021) Probing Contact Electrification: A Cohesively Sticky Problem. ACS Appl Mater Interfaces 13:44935\u0026ndash;44947. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1021/acsami.1c13100\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLi S et al Contributions of Different Functional Groups to Contact Electrification of Polymers. Adv Mater n/a, 2001307 \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/adma.202001307\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLiu Y, Liu G, Bu T, Zhang C (2021) Effects of interfacial acid\u0026ndash;base on the performance of contact\u0026ndash;separation mode triboelectric nanogenerator. Mater Today Energy 20:100686. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.mtener.2021.100686\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLi S et al (2020) Contributions of Different Functional Groups to Contact Electrification of Polymers. Adv Mater 32:2001307. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/adma.202001307\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u0026Scaron;utka A et al (2019) The role of intermolecular forces in contact electrification on polymer surfaces and triboelectric nanogenerators. Energy Environ Sci 12:2417\u0026ndash;2421\u003c/li\u003e\n\u003cli\u003eKim DW, Lee JH, Kim JK, Jeong U (2020) Material aspects of triboelectric energy generation and sensors. NPG Asia Mater 12:6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41427-019-0176-0\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eVerners O et al (2022) Smooth polymers charge negatively: Controlling contact electrification polarity in polymers. Nano Energy 104:107914\u003c/li\u003e\n\u003cli\u003ePersson BNJ (2020) On the role of flexoelectricity in triboelectricity for randomly rough surfaces. EPL (Europhysics Letters) 129:10006. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1209/0295-5075/129/10006\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLapčinskis L et al (2021) Triboelectrification of nanocomposites using identical polymer matrixes with different concentrations of nanoparticle fillers. J Mater Chem A 9:8984\u0026ndash;8990. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1039/D0TA12441A\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eZhang J et al (2021) Recent developments of hybrid piezo\u0026ndash;triboelectric nanogenerators for flexible sensors and energy harvesters. Nanoscale Adv 3:5465\u0026ndash;5486. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1039/D1NA00501D\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eXu C et al (2018) On the Electron-Transfer Mechanism in the Contact-Electrification Effect. Adv Mater 30:1706790. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/adma.201706790\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eWang ZL, Wang AC (2019) On the origin of contact-electrification. Mater Today 30:34\u0026ndash;51. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.mattod.2019.05.016\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eVerners O, Lapčinskis L, Sherrell PC, \u0026Scaron;utka A (2023) Contact Electrification at Dielectric Polymer Interfaces: On Bond Scission, Material Transfer, and Electron Transfer. Adv Mater Interfaces 10:2300562. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/admi.202300562\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eMcCarty LS, Whitesides GM (2008) Electrostatic Charging Due to Separation of Ions at Interfaces: Contact Electrification of Ionic Electrets. Angew Chem Int Ed 47:2188\u0026ndash;2207. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/anie.200701812\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eFang Y et al (1986) (2024) Static charge is an ionic molecular fragment. \u003cem\u003eNature Communications\u003c/em\u003e 15, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41467-024-46200-3\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eIm S, Frey E, Lacks DJ, Genzer J, Dickey MD Enhanced Triboelectric Charge Stability by Air-Stable Radicals. Adv Sci n/a, 2304459 \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/advs.202304459\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u0026Scaron;utka A et al (2018) Triboelectric nanogenerator based on immersion precipitation derived highly porous ethyl cellulose. J Electrostat 92:1\u0026ndash;5. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.elstat.2018.01.003\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLapčinskis L et al (2021) Triboelectrification of nanocomposites using identical polymer matrixes with different concentrations of nanoparticle fillers. J Mater Chem A 9:8984\u0026ndash;8990\u003c/li\u003e\n\u003cli\u003eLapčinskis L et al (2024) Controlling the magnitude and polarity of surface charges in PEBA polymers by adding UIO-66 MOFs. Mater Adv 5:4242\u0026ndash;4250. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1039/D3MA01172K\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLapčinskis L et al (2020) The Adhesion-Enhanced Contact Electrification and Efficiency of Triboelectric Nanogenerators. Macromol Mater Eng 305:1900638. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/mame.201900638\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u0026Scaron;utka A et al (2019) The role of intermolecular forces in contact electrification on polymer surfaces and triboelectric nanogenerators. Energy Environ Sci 12:2417\u0026ndash;2421. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1039/C9EE01078E\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLi S et al (2020) Manipulating the triboelectric surface charge density of polymers by low-energy helium ion irradiation/implantation. Energy Environ Sci 13:896\u0026ndash;907. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1039/C9EE03307F\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eFan Y et al (2021) Negative triboelectric polymers with ultrahigh charge density induced by ion implantation. Nano Energy 90:106574. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.nanoen.2021.106574\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003ePandey RK, Kakehashi H, Nakanishi H, Soh S (2018) Correlating Material Transfer and Charge Transfer in Contact Electrification. J Phys Chem C 122:16154\u0026ndash;16160. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1021/acs.jpcc.8b04357\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eBai P et al (2014) Dipole-moment-induced effect on contact electrification for triboelectric nanogenerators. Nano Res 7:990\u0026ndash;997. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1007/s12274-014-0461-8\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eAkbarinejad A et al (2024) Stretching, Tapping, or Compressing\u0026ndash;What Role Does Triboelectricity Play in the Signal Output from Piezoelectric Nanogenerators? Adv Electron Mater 10:2400019. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/aelm.202400019\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLeon RT et al (2024) Understanding and Controlling Electrostatic Discharge in Triboelectric Nanogenerators. \u003cem\u003eChemSusChem\u003c/em\u003e 17, e202400366 \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003edoi.org/10.1002/cssc.202400366\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLeon RT, Sherrell PC, \u0026Scaron;utka A, Ellis AV (2023) Decoupling piezoelectric and triboelectric signals from PENGs using the fast fourier transform. Nano Energy 110:108445. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.nanoen.2023.108445\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLeveneur J et al (2023) Surface modification of collagen using low-energy noble gas ion implantation. Surf Coat Technol 468:129768. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.surfcoat.2023.129768\u003c/span\u003e\u003c/span\u003e. https://doi.org:\u003c/li\u003e\n\u003cli\u003eSobolev YI, Adamkiewicz W, Siek M, Grzybowski BA (2022) Charge mosaics on contact-electrified dielectrics result from polarity-inverting discharges. Nat Phys. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41567-022-01714-9\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eBaytekin HT, Baytekin B, Incorvati JT, Grzybowski BA (2012) Material Transfer and Polarity Reversal in Contact Charging. Angew Chem Int Ed 51:4843\u0026ndash;4847. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/anie.201200057\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eBaytekin HT et al (2011) The Mosaic of Surface Charge in Contact Electrification. Science 333:308\u0026ndash;312. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:doi:10.1126/science.1201512\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eMizzi CA, Lin AYW, Marks LD (2019) Does Flexoelectricity Drive Triboelectricity? Phys Rev Lett 123:116103. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1103/PhysRevLett.123.116103\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eMarks LD, Olson KP, Flexoelectricity Triboelectricity, and Free Interfacial Charges. \u003cem\u003eSmall\u003c/em\u003e n/a, 2310546 \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/smll.202310546\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eOlson KP, Marks LD (2024) What Puts the Tribo in Triboelectricity? Nano Lett 24:12299\u0026ndash;12306. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1021/acs.nanolett.4c03656\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eMalone N et al (2024) Grain Boundary-Rich Tungsten Carbide Nanoparticle Films Exhibit High Intrinsic Activity Toward Hydrogen Evolution. ACS Appl Nano Mater. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1021/acsanm.3c05497\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eMalone N et al (2023) High Turnover Frequency for the Hydrogen Evolution Reaction on Molybdenum Carbide Thin Films Synthesized by Ion Implantation. ACS Appl Eng Mater 1:2377\u0026ndash;2385. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1021/acsaenm.3c00298\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eFiedler H et al (2023) Room Temperature Ion Beam Synthesis of Ultra-Fine Molybdenum Carbide Nanoparticles: Toward a Scalable Fabrication Route for Earth-Abundant Electrodes. \u003cem\u003eSmall\u003c/em\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/smll.202304118\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eFiedler H et al (2021) Tuning the electromechanical properties and polarization of Aluminium Nitride by ion beam-induced point defects. Acta Mater 203 \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85096842196\u0026amp;doi=10.1016%2fj.actamat.2020.116495\u0026amp;partnerID=40\u0026amp;md5=7ba580396f719d1710ac0e49b49372ef\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eFiedler H et al (2021) Giant Piezoelectricity of Deformed Aluminium Nitride Stabilised through Noble Gas Interstitials for Energy Efficient Resonators. Adv Electron Mater 7:2100358. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/aelm.202100358\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eBooth MA, Leveneur J, Costa AS, Kennedy J, Travas-Sejdic J (2012) Tailoring the Conductivity of Polypyrrole Films Using Low-Energy Platinum Ion Implantation. J Phys Chem C 116:8236\u0026ndash;8242. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1021/jp300682q\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u0026Scaron;utka A et al (2023) High-Performance Hybrid Triboelectric Generators Based on an Inversely Polarized Ultrahigh \u0026beta;-Phase PVDF. ACS Appl Energy Mater 6:9300\u0026ndash;9306. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1021/acsaem.3c01196\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u0026Scaron;utka A et al (2020) Measuring Piezoelectric Output\u0026mdash;Fact or Friction? Adv Mater 32:2002979. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/adma.202002979\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLees EW, Mowbray BA, Parlane FG, Berlinguette CP (2022) Gas diffusion electrodes and membranes for CO2 reduction electrolysers. Nat Reviews Mater 7:55\u0026ndash;64\u003c/li\u003e\n\u003cli\u003eFiedler H, Gupta P, Kennedy J, Markwitz A (2018) 28Si\u0026thinsp;+\u0026thinsp;ion beams from Penning ion source based implanter systems for near-surface isotopic purification of silicon. Rev Sci Instrum 89. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1063/1.5048949\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eFiedler H et al (2024) Room Temperature Ion Beam Synthesis of Ultra-Fine Molybdenum Carbide Nanoparticles: Toward a Scalable Fabrication Route for Earth-Abundant Electrodes. Small 20:2304118. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/smll.202304118\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eMutzke A, Schneider R, Eckstein W, Dohmen R, SDTrimSP (2011) Version 5.00. ipp, report,(12/8). \u003cem\u003eMax Planck-Institut fr Plasmaphysik\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eKawai H (1969) The Piezoelectricity of Poly (vinylidene Fluoride). Jpn J Appl Phys 8:975. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1143/JJAP.8.975\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u0026Scaron;utka A et al (2018) Inversely polarised ferroelectric polymer contact electrodes for triboelectric-like generators from identical materials. Energy Environ Sci 11:1437\u0026ndash;1443. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1039/C8EE00550H\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eSherrell PC et al (2022) A bright future for engineering piezoelectric 2D crystals. Chem Soc Rev 51:650\u0026ndash;671. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1039/D1CS00844G\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eHabib M, Lantgios I, Hornbostel K (2022) A review of ceramic, polymer and composite piezoelectric materials. J Phys D: Appl Phys 55:423002\u003c/li\u003e\n\u003cli\u003e\u0026Scaron;utka A et al (2024) Recycled Polystyrene Waste to Triboelectric Nanogenerators: Volumetric Electromechanically Responsive Laminates from Same Material Contact Electrification. Adv Energy Sustain Res. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/aesr.202300259\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eLinarts A, Sherrell PC, Mālnieks K, Ellis AV, \u0026Scaron;utka A (2023) Electrospinning Triboelectric Laminates: A Pathway for Scaling Energy Harvesters. Small 19:2205563. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/smll.202205563\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eZhang LA et al (2023) Collecting the space-distributed Maxwell's displacement current for ultrahigh electrical density of TENG through a 3D fractal structure design. Energy Environ Sci 16:3781\u0026ndash;3791\u003c/li\u003e\n\u003cli\u003eZhang X, Pondrom P, Sessler GM, Ma X (2018) Ferroelectret nanogenerator with large transverse piezoelectric activity. Nano Energy 50:52\u0026ndash;61. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.nanoen.2018.05.016\u003c/span\u003e\u003c/span\u003e. https://doi.org:\u003c/li\u003e\n\u003cli\u003eGhosh SK, Sinha TK, Mahanty B, Mandal D (2015) Self-poled efficient flexible Ferroelectretic nanogenerator: a new class of piezoelectric energy harvester. Energy Technol 3:1190\u0026ndash;1197\u003c/li\u003e\n\u003cli\u003eZhang X, Zhang X, Sessler GM, Gong X in \u003cem\u003e2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena.\u003c/em\u003e 579\u0026ndash;582\u003c/li\u003e\n\u003cli\u003eSimon Ž, Dharmasiri B, Harte T, Sherrell PC, Henderson LC (2024) From stress to charge: investigating the piezoelectric response of solvate ionic liquid in structural energy storage composites. Mater Horiz 11:4321\u0026ndash;4328. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1039/D4MH00612G\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003ePatnam H, Dudem B, Graham SA, Yu JS (2021) High-performance and robust triboelectric nanogenerators based on optimal microstructured poly(vinyl alcohol) and poly(vinylidene fluoride) polymers for self-powered electronic applications. Energy 223:120031. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.energy.2021.120031\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003ePang Y et al (2021) Hybrid Energy-Harvesting Systems Based on Triboelectric Nanogenerators. Matter 4:116\u0026ndash;143. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003edoi.org/10.1016/j.matt.2020.10.018\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eZhao C et al (2019) Hybrid piezo/triboelectric nanogenerator for highly efficient and stable rotation energy harvesting. Nano Energy 57:440\u0026ndash;449. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.nanoen.2018.12.062\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eHan M, Chen X, Yu B, Zhang H (2015) Coupling of Piezoelectric and Triboelectric Effects: from Theoretical Analysis to Experimental Verification. Adv Electron Mater 1:1500187. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/aelm.201500187\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003eWasserman B (1986) Fractal nature of electrical conductivity in ion-implanted polymers. \u003cem\u003ePhysical Review B\u003c/em\u003e 34, 1926\u0026ndash;1931 https://doi.org:10.1103/PhysRevB.34.1926\u0026nbsp;\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-5436005/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5436005/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eIon implantation is a powerful tool to modify materials chemistry and structure. The implantation process was considered to result in a net-neutral material, due to implanted ionic charge being compensated by the host materials lattice. Here, we show ion implantation into polytetrafluoroethylene (PTFE) results in an uncompensated ‘space charge’ region – requiring a reconsideration of ion implantation into polymers. This is demonstrated via electromechanical testing of Cu implanted PTFE as a triboelectric nanogenerator (TENG). Previously, ion implantation into polymers has shown to increase TENG performance, attributed to increasing the prevalence of electron transfer during contact-separation testing. This attribution to electron transfer is incorrect, with significant electromechanical conversion being observed in 1 x 10\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e16\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e Cu ions cm\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e− 2\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e implanted polytetrafluoroethylene (PTFE) in both piezoelectric mode testing and in non-contact induction measurements – where electron transfer cannot occur. These results, indicate that the implantation of Cu ions creates a space charge effect in the PTFE matrix, and the subsequent charge asymmetry creates an electric field enhancing TENG performance, analogous to hybrid piezoelectric-TENGs. \u003c/strong\u003e\u003cem\u003eThese results demonstrate that ion implanted polymers possess space charge and can be used directly for sensing, creating a new pathway for electromechanical conversion materials.\u003c/em\u003e\u003c/p\u003e","manuscriptTitle":"Space charge drives electromechanical conversion via a piezoelectric-like effect in ion implanted polymers","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-11-25 09:40:45","doi":"10.21203/rs.3.rs-5436005/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"354c04ef-a2b0-4745-ae32-63436c392a02","owner":[],"postedDate":"November 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":40579819,"name":"Physical sciences/Materials science/Soft materials/Polymers"},{"id":40579820,"name":"Physical sciences/Physics/Chemical physics"}],"tags":[],"updatedAt":"2026-05-14T14:13:54+00:00","versionOfRecord":{"articleIdentity":"rs-5436005","link":"https://doi.org/10.1103/th79-cjz6","journal":{"identity":"physical-review-letters","isVorOnly":true,"title":"Physical Review Letters"},"publishedOn":"2026-02-06 00:00:00","publishedOnDateReadable":"February 6th, 2026"},"versionCreatedAt":"2024-11-25 09:40:45","video":"","vorDoi":"10.1103/th79-cjz6","vorDoiUrl":"https://doi.org/10.1103/th79-cjz6","workflowStages":[]},"version":"v1","identity":"rs-5436005","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5436005","identity":"rs-5436005","version":["v1"]},"buildId":"zQwnuV7TCBrMSSSToR1PI","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}