Unveiling the Myths of Co-deposition of Hole Conductors and Perovskite Layers: A Mechanistic Study

Unveiling the Myths of Co-deposition of Hole Conductors and Perovskite Layers: A Mechanistic Study | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 14 September 2025 V1 Latest version Share on Unveiling the Myths of Co-deposition of Hole Conductors and Perovskite Layers: A Mechanistic Study Authors : Xi Yang 0009-0005-4418-3616 , Kaifeng Jing , Hengyu Zhang , Qianyi Li , Dongyang Li , Patrick W. K. Fong , Zhenyi Ni , Guang Yang [email protected] , and Gang Li Authors Info & Affiliations https://doi.org/10.22541/au.175787876.66475389/v1 218 views 87 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Perovskite solar cells (PSCs) hold great promise as photovoltaic technology, with power conversion efficiencies exceeding 27%. To further reduce the levelized cost of energy, simplifying PSC manufacturing processes is essential. In this study, we introduce a streamlined one-step solution-coating strategy that simultaneously deposits both the hole-conductor and perovskite layers. We demonstrate that doped self-assembled monolayers (SAMs), containing phosphonic or carboxylic acids, diffuse and spontaneously assemble on both indium tin oxide (ITO) substrates and perovskite surfaces during film formation. This process results in a stable monolayer that functions as an efficient hole-selective contact while promoting favorable perovskite crystallization. Moreover, the incorporation of a functional isolation layer effectively mitigates the side effects induced by perovskite-anchored SAMs, thereby enhancing device efficiency and stability. The resulting PSCs exhibit a remarkable power conversion efficiency of 25.1% and maintain over 85% of their initial performance after 1000 hours of maximum power point tracking under continuous illumination. Introduction Perovskite solar cells (PSCs) have achieved impressive power conversion efficiencies (PCEs) approaching 27%, 1 driven by advances in compositional engineering, solvent engineering, interface engineering, and defect passivation. 2, 3, 4 To further enhance the scalability and commercial viability of PSCs, it is crucial to simplify device fabrication while maintaining high efficiency, thereby reducing manufacturing complexity and costs. Self-assembled monolayers (SAMs) have been widely adopted as hole-selective layers in high-performance inverted PSCs due to their ability to tailor chemical and physical interface properties. However, achieving uniform SAM coverage remains a challenge, as densely packed monolayers often exhibit incomplete substrate anchoring. 4, 5, 6 The inherent hydrophobicity of SAMs can also limit their applicability in large-scale device fabrication. 5, 7, 8 Despite these challenges, SAMs have demonstrated compatibility with co-processing alongside perovskite layers, enhancing both PSC efficiency and stability while streamlining fabrication processes. 4, 9, 10, 11 The co-deposition of perovskite layers with SAMs can modulate perovskite crystal growth through strong coordination interactions, simultaneously passivating surface and grain boundary defects. 10, 12, 13 For example, Zheng et al. reported spontaneous co-deposition of SAM and perovskite layers, achieving inverted PSCs with a PCE exceeding 24.5% and enhanced operational stability. 10 He et al. further demonstrated effective doping of perovskite with different types of SAMs, pushing the PCE to approach 26%. 13 Nevertheless, the spatial distribution of SAMs within perovskite films and their influence on crystallization dynamics when incorporated into perovskite precursor inks remain unclear. In this work, we developed a one-step co-deposition strategy to simultaneously form the SAM and perovskite layer, enabling efficient and stable inverted PSCs. We show that the incorporation of SAM molecules effectively modulates crystallization kinetics, optimizing film growth to achieve highly oriented, high-quality perovskite films. 13, 14 We further elucidated the diffusion dynamics of doped SAM molecules during perovskite formation, revealing their dual interfacial anchoring behavior—binding to both the ITO substrate and the Pb-rich perovskite surface. While tuning SAM concentration eliminates non-uniform ITO coverage, it induces undesirable top-surface accumulation, which increases non-radiative recombination and compromises device efficiency. 5, 15, 16 To address this limitation, we introduced an isolation strategy that suppresses interfacial losses. By synergistically combining this isolation and co-deposition strategy, we realized PSCs with a champion PCE of 25.1% and operational stability exceeding 1000 hours under continuous illumination. Results and Discussion We investigated baselined inverted PSCs with the architecture of glass/ITO/SAM (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid, 4PADCB)/ Cs 0.05 FA 0.85 MA 0.1 PbI 3 /C60/ bathocuproine (BCP)/Ag, where FA is formamidinium and MA is methylammonium, respectively. For the perovskite recipe, a 3% excess of PbI₂ was added to enhance device performance. Regarding the co-deposition strategy, the corresponding device structure is illustrated in Figure 1a (glass/ITO/Cs 0.05 FA 0.85 MA 0.1 PbI 3 &SAM/C60/BCP/Ag), where SAM molecule was incorporated into perovskite precursor and spin-coated directly on ITO substrate 10, 17 . The chemical structure of 4PADCB is shown in Figure 1c . In this work, the typical inverted perovskite devices are labeled as the control, while those fabricated using the co-deposition strategy are designated as the target. To investigate the spatial distribution of the 4PADCB SAM molecules in perovskite films, we performed depth profiling on target perovskite films using time-of-flight secondary ion mass spectrometry (TOF-SIMS). In the target perovskite film, a distinct phosphorus signal from 4PADCB molecules was detected at both the bottom (ITO/perovskite interface) and top (perovskite/C60 interface) surfaces ( Figure 1b and d ), which is identical to previous study. 10 This result suggests that 4PADCB molecules diffused and migrated to both interfaces during film formation. We attribute these phenomena to robust interfacial chemical bonding between: (1) the ITO substrate and the SAM, 18 and (2) Pb-rich perovskite surface and the SAM, particularly through In-P and Pb-P coordination. 19 While the successful deposition of SAMs on the ITO surface via co-deposition strategy was expected, the accumulation of SAM molecules at the top interface degrades device performance. This is due to the insertion of a p-type layer between the perovskite and the electron-selective layer, which promotes severe charge recombination—a phenomenon we will discuss in detail later The primary objective of our co-deposition strategy is to form a continuous, uniform SAM layer on the ITO substrate. To evaluate the uniformity of the SAM layers, we measured the average surface contact potential difference (CPD) of SAM-coated substrates in both control and target samples using Kelvin probe force microscopy (KPFM) under various conditions. 20 Figure 1e shows the CPD histograms of different samples. The pure SAM reference denotes SAM-coated ITO without solvent washing. For the co-deposition approach, we tested two samples with different SAM concentrations (1 mg/mL and 3 mg/mL). The resulting samples were washed with N,N′-dimethylformamide (DMF) prior to measurement. The co-deposited samples exhibited a CPD value of 484 meV, comparable to that of the pure SAM reference, indicating that the co-depositing strategy successfully formed a robust SAM layer on the ITO substrate. However, the full width at half maximum (FWHM) values increased for the co-deposited samples (38 meV for the 1 mg/mL sample and 66 meV for the 3 mg/mL sample) compared to the pure SAM layer (16 meV), suggesting reduced uniformity and surface smoothness in the washed co-deposited SAM layer. This phenomenon possibly originates from partial disruption of the SAM structure during DMF washing. Supporting this interpretation, DMF-washed pure SAM layers on ITO (denoted Washed SAM) showed a comparable FWHM increase to 37 meV ( Supplementary Figure 1 ). Moreover, the co-deposited sample at a higher concentration (3 mg/mL) exhibits a broader FWHM value of 66 meV compared to the lower concentration sample (1 mg/mL, 38 meV). This suggests increased nonuniformity and inhomogeneity of SAM layers, likely due to variations in molecular packing density or incomplete surface coverage. The enhanced uniformity of the low-concentration (1 mg/mL) co-deposited SAM layer may result from minimized molecular aggregation. To evaluate the adhesion, robustness, and quality of the 4PADCB layer on the ITO surface after perovskite co-deposition, we selectively dissolved and removed the perovskite film using DMF washing. The entire device was then refabricated ( Supplementary Figure 2 provides with the detailed procedure). Notably, the re-deposited devices exhibited performance comparable to that of the control pin devices ( Supplementary Figure 3 and Supplementary Table 1 ). Combined with the TOF-SIMS and KPFM results, these findings strongly suggest that robust SAMs were formed on the ITO surface during perovskite film processing. The observations indicate that co-deposited 4PADCB molecules diffuse to both the top and bottom interfaces, ultimately forming a stable and densely packed SAM layer after deposition of the SAM-doped perovskite film. Figure 1. Diffusion and drift dynamics of SAM molecules during the crystallization of perovskite films (a) Diagrams showing the device stack, illustrating the layers of devices, including both the control and co-deposition PSCs. (b) A schematic diagram depicting the bidirectional diffusion of the SAM layers in the co-deposition PSCs. (c) The molecular structure of the 4PADCB self-assembled monolayer. (d) Time-of-flight secondary ion mass spectrometry (TOF-SIMS) profile of the co-deposition perovskites films on ITO substrate. (e) Contact potential difference (CPD) distribution of pure SAM layer and co-deposition samples with various SAM concentrations after removing perovskite layers. 4PADCB Co-Deposition molecules in-situ influence in perovskite crystallization After verifying the diffusion process and spatial distribution of SAM molecules in the co-deposition approach, we further investigated the impact of SAMs on the perovskite film crystallization process, as the functional groups in SAM molecules may chemically interact with the perovskite precursor species. 18, 21, 22 After introducing 4PADCB molecules, no changes in UV-Visible (UV-vis) absorption and bandgap were observed in the target perovskite film compared to the control film ( Supplementary Figure 4 ). To study the crystallization kinetics, we performed in-situ time-resolved UV-vis absorption spectroscopy on as-deposited perovskite films during thermal annealing process ( Figure 2a and b ). For the control perovskite films, the as-prepared film shows strong UV absorption at around 430 nm, attributed to the solvent complex. 23 The peak disappears after approximately T₁=8 s, confirming the complete elimination of the solvent complex. During this stage, nucleation sites emerge as the solution concentration surpasses saturation. Shortly thereafter (T₂=9 s), we observe a rapid absorbance change, signaling substantial perovskite crystallite formation in the solid precursor film. A similar solvent complex elimination timeframe (T₁=8 s) is observed in the target films. However, the introduction of SAM molecules delays the initial perovskite crystallization, prolonging the rapid absorbance change to T₂=11 s. Real-time UV-vis spectra analysis confirm that the incorporation of SAM molecules in perovskite precursor can modulate the crystallization process. X-ray diffraction (XRD) measurement was further carried out to study the crystallinity difference of control and target films. As shown in Figure 2c and d , the target film demonstrates enhanced crystalline quality, evidenced by stronger diffraction peaks at 14.1° and 28.4°, corresponding to the (110) and (220) lattice planes, respectively. Additionally, the XRD patterns show a suppressed PbI₂ peak at 12.5°, suggesting reduced unreacted PbI₂ due to the doped 4PADCB. 24 This indicates that 4PADCB interacts with PbI₂ during film formation, likely forming amorphous PbI₂–4PADCB complexes that inhibit crystalline PbI₂ retention. 25 Furthermore, we investigated the film morphologies of both control and target perovskite films using scanning electron microscopy (SEM), as shown in Figure 2e, f, g and h . Top-view SEM images reveal that the target film exhibits significantly smoother surface morphology and larger grain size compared to the control film ( Figure 2e and g ). Cross-sectional SEM analysis ( Figure 2f and h ) further demonstrates the formation of large, well-defined columnar grains with preferred orientation, consistent with the top-view observations and XRD results. These morphological improvements in the target film correlate well with its enhanced optoelectronic properties, as will be detailed in the following discussion. Figure 2. Impact of co-deposition strategy on perovskite crystallization (a) , (b) In-situ UV-visible spectra of the control pure perovskite film and the target co-deposition perovskite film during annealing. (c), (d) X-ray diffraction (XRD) spectra of control pure perovskite films and target co-deposited perovskite films on indium tin oxide (ITO) substrates. (e-h) Scanning electron microscopy (SEM) images showing the top views (e) and (g), and the cross-sectional views (f) and (h) of perovskite films: (e, f) for the control perovskite film and (g, h) for the target perovskite film. Post Processing of the diffused SAM molecules on top surface Although the co-deposition strategy enables the introduction of a SAM layer at the bottom ITO surface and enhances crystallinity and film quality, it inevitably leads to the formation of p-type SAM molecules on the perovskite top surface. 7, 26 This unintended SAM-anchoring on top surface impedes charge carrier transport and promotes non-radiative recombination, potentially compromising device performance. 27, 28 To elucidate the detrimental effects of diffused SAM molecules at the top surface, we systematically investigated the optoelectronic properties of perovskite films. As shown in Figure 3a and b , photoluminescence (PL) mapping characterization demonstrated significantly reduced PL intensity in the target perovskite film compared to the control sample. This PL quenching phenomenon can be attributed to accelerated charge transfer induced by residual SAM molecules on the film surface. The post passivation process significantly reduced the disadvantage of 4PADCB reserve accumulation and enhanced PL intensity in the 4PADCB-doped perovskite film relative to the reference samples, indicating improved optoelectronic quality that was higher than the controlled pure perovskite ( Figure 3c ). Density of states of traps (tDOS) results of the 4PADCB-doped co-deposition perovskite film with and without passivation ( Figure 3e ) also showed that the passivation process decreased the DOS of traps, indicated the passivation suppression effect to defects by 4PADCB reserve diffusion on perovskite top surface. This hypothesis was further corroborated by time-resolved photoluminescence (TRPL) spectroscopy in Figure 3d . Quantitative analysis revealed a significantly accelerated PL decay kinetics in the target perovskite film relative to the control, with average carrier lifetimes decreasing from 158.6ns to 135.9ns (Supplementary Table 2 ). To address the detrimental impact of excess SAM molecules at the perovskite surface, we developed an isolation layer through spin-coating of a mixed ammonium salt solution consisting of 4-Fluoro-Phenethylammonium iodide (F-PEAI) and Benzylammonium iodide (BAI) in a 2:1 molar ratio in IPA. This engineered interfacial layer serves to passivate surface defects while minimizing undesirable contact between p-type SAM and n-type C60. 29 Supplementary Figure 5 presents top-view and cross-sectional SEM images of the target films with isolation layers. The top-view SEM images reveal distinct morphological changes, particularly the apparent blurring of grain boundaries, which provides clear evidence of successful isolation layer formation on the perovskite surface. 14, 30 As shown in Figure 3c , the PL mapping image of the target sample with an isolation layer exhibits the highest PL intensity and longest lifetime compared to the control and target films. The TRPL results further confirm that introducing an isolation layer enhances charge carrier lifetime, increasing from 135.9ns to 204.8ns (Figure 3d and Supplementary Table 2 ). We then employed thermal admittance spectroscopy to characterize the trap density in target devices with and without the isolation layer. As shown in the trap density of state (tDOS) spectra ( Figure 3e ), the device with the isolation layer exhibited a lower overall trap density compared to the device without it. To further investigate how the isolation layer spatially reduces trap density, we conducted drive-level capacitance profiling (DLCP) measurements. The results clearly demonstrate a reduction in defect concentration near the C60/perovskite interface. Additionally, the measured carrier concentration levels indicate that the post-passivation process effectively reduced defects and trap densities, consistent with the tDOS results. Figure 3. Isolating impact on optoelectronic properties of co-deposition perovskites (a-c) Photoluminescence (PL) mapping images of control perovskite film (a), target perovskite film (b), and isolated target perovskite film (c). (d) Time-resolved photoluminescence (TRPL) decay spectra of control, target, and isolated target perovskite films. (e), (f) Density of states of traps (tDOS) (e) and drive-level capacitance profiling (DLCP) (f) curves of target PSCs with and without isolation layer. Photovoltaic Performance of the 4PADCB doped Co-deposition PSC We systematically evaluated the performance of control and target Cs 0.05 (FA 0.85 MA 0.1 ) 0.95 PbI 3 -based PSCs with and without isolation layers. By fabricating target devices with 4PADCB concentrations ranging from 0.5 mg/mL to 3 mg/mL ( Supplementary Figure 6 and Supplementary Table 3 ), we identified 1 mg/mL as the optimal concentration for best performance. At higher concentrations, excessive 4PADCB diffusion and deposition on the top surface hindered electron transport and increased non-radiative recombination, resulting in notable reductions in both open-circuit voltage ( V OC ) and short-circuit current density ( J SC ). 10 Conversely, lower 4PADCB concentrations also slightly diminished the power conversion efficiency (PCE). This performance loss is associated with a decrease in the V OC , which is likely caused by incomplete formation of the SAM on ITO substrate. 4, 31 These findings underscore the importance of optimizing additive concentration to balance effective interfacial passivation and optimal device electrical characteristics. Figure 4a presents the representative current density-voltage ( J-V ) curves for the four different devices. The control devices (without an isolation layer) achieved a PCE of 22.1%, with an V OC of 1.13 V, a J SC of 24.55 mA cm⁻², and a fill factor (FF) of 79.19%. The control device with an isolation layer displayed an intermediate PCE of 23.3%, outperforming the target device without isolation but underperforming relative to the target device with isolation. In contrast, the target devices (without an isolation layer) exhibited significantly inferior performance, yielding a PCE of only 19.1% ( V OC =1.10 V, J SC = 23.51 mA cm⁻², FF = 73.55%). We attribute this reduction to severe interfacial recombination losses. To address this issue, we introduced an isolation layer, which substantially enhanced device performance. The target devices incorporating the isolation layer delivered a champion PCE of 25.1%, accompanied by a V OC of 1.16 V, a J SC of 25.6 mA cm⁻², and an FF of 84.4% ( Supplementary Table 4 ). To elucidate the function of the isolation layer, we measured the external quantum efficiency of electroluminescence (EQE EL ) for target devices with and without isolation layers. As shown in Supplementary Figure 7 , the target device with an isolation layer exhibits an EQE EL of 1.65% at an injection current equivalent to J SC , whereas the device without the isolation layer shows a significantly lower EQE EL of 0.027%. Additionally, the Mott-Schottky plot ( Supplementary Figure 8 ) reveals a substantial increase in built-in potential (V bi ) from 1.08 V to 1.15 V upon incorporating the isolation layer. These results demonstrate that excess SAM on the perovskite surface impedes charge transfer, leading to severe V OC losses, which the isolation layer effectively mitigates. Notably, all photovoltaic parameters exhibited significant improvement compared to the target devices without the isolation layer. The corresponding external quantum efficiency (EQE) spectra ( Figure 4b ) further corroborated these findings, with the integrated current densities showing excellent agreement with the J SC values obtained from the J-V measurements. EQE spectrum revealed a perovskite bandgap of approximately 1.53 eV ( Supplementary Figure 9 ). To quantify nonradiative recombination losses, we measured the quasi-Fermi-level splitting (QFLS). 32 As illustrated in Figure 4d , the control devices displayed a QFLS of Conversely, target devices without the isolation layer exhibited the lowest QFLS (~1.18 eV), while those with the isolation layer achieved the highest value (1.22 eV). This trend underscores the suppression of nonradiative recombination, consistent with the enhanced J-V performance. Further analysis of the QFLS data enabled decoupling of the individual contributions from the co-deposition strategy and the isolation layer, revealing two key mechanisms: (1) Interfacial defect passivation: The isolation layer effectively passivates interfacial defects and prevents direct contact between C 60 and residual SAM molecules on the perovskite surface; (2) Bulk perovskite film quality: The co-deposition strategy further enhances bulk perovskite quality, leading to improved optoelectronic properties. 32, 33 To assess reproducibility, we analyzed the statistical distribution of PCEs across 12 devices for each case ( Figure 4c ). The histograms demonstrated the good reproducibility for devices fabricated using the co-deposition strategy in conjunction with the isolation layer approach. While confirming the adaptability of SAMs in co-deposition strategy by fabricating target devices with different SAM molecules, we identified 4PADCB as the optimal SAM molecule in co-deposition PSCs with the best performance ( Supplementary table 5 ). To evaluate the operational stability of the fabricated devices, we performed accelerated aging tests through maximum power point tracking (MPPT) under continuous 1-sun equivalent illumination (AM 1.5G, 100 mW cm⁻²). Unencapsulated devices were systematically characterized in a controlled N₂ atmosphere to isolate degradation mechanisms ( Figure 4e ). The target devices incorporating the isolation layer demonstrated good stability, maintaining 85% of their initial power conversion efficiency (PCE) after 1000 hours of continuous operation. In stark contrast, control devices lacking the isolation layer exhibited significantly faster degradation kinetics, retaining only 68% of their initial PCE over the same testing period. These results provide compelling evidence for the critical role of the isolation layer in mitigating device degradation pathways. 4, 34, 35, 36 Figure 4. Photovoltaic performance of PSCs. (a) J – V curves of the 1.53 eV PSC devices of control and target PSCs with and without isolation layers. (b) The corresponding EQE spectrum. (c) Statistical device PCEs. The central line is the median value, the central point is the mean value, the box gives the standard deviation, and the whiskers represent the minimum and maximum values. In the statistics, 12 devices were used for each condition. (d) QELS mapping of control and target perovskite films with and without isolation layers. (e) Operational stability MPPT of the target PSCs with and without isolation layers. Conclusion In this work, we elucidate the working mechanism of co-deposition of hole conductors (SAM) with perovskite layers to achieve efficient and stable PSCs. During film formation, SAM molecules undergo bidirectional diffusion, spontaneously migrating to both the ITO bottom contact and perovskite top surface, enabling the simultaneous formation of SAMs on ITO and perovskite surfaces. Our findings reveal key insights into the behavior of co-deposited SAM molecules, including their diffusion dynamics, in-situ crystallization enhancement, and defect passivation capabilities—all of which critically influence device efficiency and stability. To address the challenge of excessive SAM accumulation at the perovskite surface, we developed an isolation layer strategy that effectively mitigates performance losses while maintaining the processing advantages. This integrated approach not only simplifies manufacturing but also delivers high-performance devices, representing a significant step toward scalable and sustainable PSC production. Methods Materials Lead iodide (PbI 2 , 99.99%) was purchased from TCI. Cesium iodide (CsI, 99.999%) was purchased from Sigma-Aldrich. Formamidinium iodide (FAI, 99.99%), methylammonium iodide (MAI, 99.99%) and methylammonium chloride (MACl, 99.9%) were purchased from Greatcell Solar. 4PADCB, MeO-2PACz, Me-4PACz purchased from Tokyo Chemical Industry-America. C 60 and BCP were purchased from the Luminescence Technology. Anhydrous solvents including N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), chlorobenzene (CB), and isopropanol (IPA) were purchased from Sigma-Aldrich. Device Fabrication The glass/ITO substrates were cleaned with DI water, acetone and isopropanol (IPA) in the ultrasonication, and then dried with nitrogen. Before fabricating, the substrates were treated by UV/ozone for 15 mins. The baseline (control) of the perovskite solution precursor was 1.6 M Cs 0.05 FA 0.85 MA 0.1 PbI 3 with 1.53 eV bandgap, dissolved in DMF & DMSO with 4:1 (v/v) in the nitrogen glovebox. For the target device, the 1 mg/ml 4PADCB perovskite solution was prepared by adding 1 mg 4PADCB powder to 1 ml perovskite precursor solution. To achieve lower concentration of 0.5 mg/ml 4PADCB perovskite co-deposition precursors, we mixed 1 mg/ml 4PADCB perovskite solution with the control perovskite precursor with the rate 1:1(v/v) for 0.5 mg/ml and 1:3(v/v) for 0.25 mg/ml. The hole-selective layer and perovskite layer were cast in a single coating step in the nitrogen glove box. The target perovskite precursor containing 4PADCB was spin-coated onto UV/ozone-treated glass/ITO substrates at 1000 r.p.m. for 5 s and 5,000 r.p.m. for 30 s, and then 180 µl CB as the antisolvent was dropped onto the spinning substrate 10 s before the end of the spin coating process. Then the target sample was annealed at 100 °C for 30 min. For the surface isolation, the mixture of F-PEAI (1 mg ml −1 ), PEAI (0.5 mg ml −1 ) and BAI (0.5 mg ml −1 ) dissolved in IPA was spun on the annealed perovskite film at 5000 r.p.m. for 30s and then annealed at 100 °C for 10 mins. The target and control devices were completed by sequentially thermally evaporating C 60 (30 nm), BCP (6 nm) and silver (100 nm) onto the stack. Characterization The J–V characteristics of the devices were measured using Keithley 2400 source meter unit under a calibrated solar simulator from Enli Technology Co., with an AM 1.5 filter. The J–V curves were obtained within the range of -0.1 to 1.2V for both reverse and forward scans. The EQE measurements were conducted using a QE-R3011 system from Enli Technology Co. The QFLS measurements were performed using a QFLS-Maper from Enli Technology Co. The devices were measured under monochromatic light, split from 300 nm to 900 nm with a step size of 10 nm. For EL, the device operates as an LED, recorded by an LED photoluminescence quantum yield measurement system (Enli Tech LQ-100) equipped with a Keithley 2400 Source Measure Unit. For in-situ UV-vis absorption spectra, an F20-UVX spectrometer (Filmetrics, Inc.) was used on measurement. Crystalline structure was explored on a Rigaku SmartLab X-ray diffractometer with Cu Kα radiation in a step of 0.01° and θ–2θ scan mode from 5° to 40°. SEM was performed on a Crossbeam 540 SEM (Carl Zeiss). The measurement of TOF‐SIMS was conducted by TOF SIMS 5-100 (ION-TOF GmbH). KPFM measurements were recorded using a MultiMode 8-HR atomic force microscope (AFM, Bruker) in the FM-KPFM mode. Steady state photoluminescence (PL) and time-resolved photoluminescence (TRPL) transient decay spectrum were acquired using FLS 1000 PL spectrometer. For DLCP measurements, an Agilent E4980A precision LCR meter was used with scanning range of the ac frequency from 0.02 to 500 kHz and the dc bias from 0 V to 1.2V for the single crystal detectors. The tDOS of solar cells were derived from the thermal admittance spectroscopy (TAS) measurement by Agilent E4980A as well. Acknowledgements G.Y. acknowledges funding support from the start-up fund provided by PolyU (1-BEBB), PRI strategic Grant (1-CDJ7), RISE strategic Grant (U-CDCC) and RIAM critical-mass strategic fund (1-CDLF). G.L. acknowledges the financial support from the Research Grants Council of Hong Kong (Project Nos. 15307922, C7018-20G, C4005-22Y), the Hong Kong Innovation and Technology Commission (ITF-TCFS GHP/380/22GD), the Hong Kong Polytechnic University (the Sir Sze-yuen Chung Endowed Professorship Fund (8-8480)), PRI strategic Grant (1-CD7X), RISE strategic Grant (Q-CDBK). This work was supported by National Natural Science Foundation of China (52302333), Guangdong Basic and Applied Basic Research Foundation (2023A1515012788) and Shenzhen Science and Technology Program (KQTD20221101093647058, ZDSYS20210706144000003). Contributions G.Y. and G.L. conceived the idea and supervised the project. X.Y. designed and performed the most of the experiments. K.J. performed SEM and XRD measurements. H.Z. and Z.N. performed PL-mapping measurement. D.L. contributed to KPFM measurement. Y.C. and Y.B. contributed to the optimization of tandem device. G.Y. and X.Y. contributed to the writing of this manuscript. All authors contributed to reviewing of the manuscript. References 1. Green MA, Dunlop ED, Yoshita M, Kopidakis N, Bothe K, Siefer G , et al. Solar cell efficiency tables (Version 64). Progress in Photovoltaics: Research and Applications 2024, 32 (7) : 425-441.2. Yang G, Wang C, Lei H, Zheng X, Qin P, Xiong L , et al. 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Keywords co-deposition strategy manufacturing process simplification normal bandgaps perovskite solar cell Authors Affiliations Xi Yang 0009-0005-4418-3616 The Hong Kong Polytechnic University View all articles by this author Kaifeng Jing The Hong Kong Polytechnic University View all articles by this author Hengyu Zhang Zhejiang University View all articles by this author Qianyi Li The Hong Kong Polytechnic University View all articles by this author Dongyang Li The Hong Kong Polytechnic University View all articles by this author Patrick W. K. Fong The Hong Kong Polytechnic University View all articles by this author Zhenyi Ni Zhejiang University View all articles by this author Guang Yang [email protected] The Hong Kong Polytechnic University View all articles by this author Gang Li The Hong Kong Polytechnic University View all articles by this author Metrics & Citations Metrics Article Usage 218 views 87 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Xi Yang, Kaifeng Jing, Hengyu Zhang, et al. Unveiling the Myths of Co-deposition of Hole Conductors and Perovskite Layers: A Mechanistic Study. Authorea . 14 September 2025. DOI: https://doi.org/10.22541/au.175787876.66475389/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . 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