High-Performance Photoresistors Based on Perovskite Thin Film with a High PbI(2) Doping Level

We prepared high-performance photoresistors based on CH(3)NH(3)PbI(3) films with a high PbI(2) doping level. The role of PbI(2) in CH(3)NH(3)PbI(3) perovskite thin film was systematically investigated using scanning electron microscopy, X-ray diffraction, time-resolved photoluminescence spectroscopy, and photoconductive atomic force microscope. Laterally-structured photodetectors have been fabricated based on CH(3)NH(3)PbI(3) perovskite thin films deposited using precursor solution with various CH(3)NH(3)I:PbI(2) ratios. Remarkably, the introduction of a suitable amount of PbI(2) can significantly improve the performance and stability of perovskite-based photoresistors, optoelectronic devices with ultrahigh photo-sensitivity, high current on/off ratio, fast photo response speed, and retarded decay. Specifically, a highest responsivity of 7.8 A/W and a specific detectivity of 2.1 × 10(13) Jones with a rise time of 0.86 ms and a decay time of 1.5 ms have been achieved. In addition, the local dependence of photocurrent generation in perovskite thin films was revealed by photoconductive atomic force microscopy, which provides direct evidence that the presence of PbI(2) can effectively passivate the grain boundaries of CH(3)NH(3)PbI(3) and assist the photocurrent transport more effectively.