Nanorod-Like Nanocrystalline CsSnI3 and CNTs Composite Thin Film-Based Hybrid Photodetector

Abstract An experimental detail on the morphology engineering and characterizations of the all-inorganic Sn-based perovskite (here CsSnI3) thin films and their application in photodetectors are presented. In particular, we demonstrated that the chlorobenzene anti-solvent treatment during thin film spin-coating could effectively optimize the morphology properties of the obtained CsSnI3 thin film. SEM and AFM measurements showed the uniform thin film with nanorod-like nanocrystalline morphology. In addition, EDS and XPS measurements confirmed the low level of oxidation of the thin film, indicating good ambient stability. A planar photodetector was also made with the prepared thin film, and electrical characteristics were taken. The dark current and photocurrent were found in the range of 10-9 A and 10-7 A, respectively, with an on/off ratio of 102. The photoresponsivity was 10-5 AW-1. A further experiment was conducted to make composite thin films between CsSnI3 and CNTs for additional morphological engineering. The SEM measurement and Raman mapping manifested the nanonet-like morphology of the composite thin film. The quenching of the PL curve indicated the efficient photo-generated carrier extraction from the CsSnI3 matrix to CNTs. The absorption spectra also showed enhanced absorption ability of the prepared composite thin film. A hybrid photodetector made from the composite thin film showed dark current and photocurrent in the range of 10-6 A and 10-4 A, respectively, with an on/off ratio of 102. The photoresponsivity was 10-2 AW-1. Due to the combination of the CNTs with CsSnI3, The photoresponsivity increased 1000 times. At the same time, the hysteresis of the hybrid photodetector also reduced significantly compared to pristine CsSnI3-based photodetector.