Microwave-Assisted Synthesis of Pb-Free MASnI _{3– <i>x</i>} Cl _<i>x</i> Mixed-Halide Perovskite Films for Flexible Photodetectors

Flexible photodetectors are receiving increasing attention due to the rapid expansion of micro/nanotechnology and wearable electronics, valued for their flexibility and light sensitivity in areas such as healthcare and smart devices. This study presents a lead-free MASnI3–xClx mixed-halide perovskite film prepared via a low-cost drop-casting method enhanced by microwave-assisted processing. We investigated the effect of microwave power and found optimal film properties at 240 W. The resulting MASnI3–xClx film exhibited a crystallite size of ∼32 nm, surface RMS of 0.0250 nm, and a band gap of 1.19 eV. The performance of the MASnI3–xClx-based photodetector was thoroughly evaluated across varying wavelengths, intensities, and flexibility. The device demonstrated excellent broadband response, achieving a responsivity of 30.4 μA/W, detectivity of 4.36 × 107 Jones, and external quantum efficiency of 6.87 × 10–5 under 400 nm illumination at 22 mW/cm2. It also showed a fast response with rise and decay times of 41 and 69 ms, respectively. Crucially, flexibility tests confirmed strong mechanical robustness. While the photoresponse gradually decreased with increased bending cycles, the dark current remained stable, and response times shifted slightly (44–82 ms rise time, 63–100 ms decay time). These results establish the MASnI3–xClx-based photodetector as a promising candidate for developing low-cost, flexible, high-performance perovskite-based optoelectronic applications.