Photodetectors are widely used in various fields of applications such as optical communication, imaging, and biomedical sensing due to their ability to convert light signals to electrical signals. Although various perovskite materials have been studied for to exhibit photodetection behavior, their potential in commercial applications is dramatically restricted owing to the toxic lead element. Recently, lead-free perovskites have attracted scientists due to optoelectronic properties comparable with lead-based materials, including tunable bandgaps, long diffusion, and high carrier mobility. However, these perovskites are usually not stable under ambient condition, which seriously degrades the device performance. In this thesis, an organic-inorganic lead-free-based halide perovskite photodetector is studied to improve the material stability and device photoresponse. Sn-doped MA2FASb2I9 thin film is optimized by finding an ideal ratio of MAI:FAI:SbI3:SnI2. The precursor solution is mixed with cellulose nanocrystals (CNCs) solution to synthesize a paper-like light absorbing film by the vacuum filtration method. Finally, the photodetector device is fabricated by depositing interdigitated Ti/Au (5 nm/95 nm) electrodes on the film to form a stable and flexible photodetector. The flexible device based on Sn-doped MA2FASb2I9/CNCs thin film exhibits a noticeable photoresponse with a responsivity of 0.85 × 10−3 AW-1, response time of ~60 ms, and good air stability under 650 nm laser irradiation at a bias of 3 V. The photodetector device demonstrated herein holds the potential for the future development of lead-free, stable, and flexible optoelectronic applications.

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