Lead-free tin-based perovskites nanocrystals for high-performance self-driven bulk-heterojunction photodetectors

Currently, photodetectors based on metal-halide perovskites are the fastest-emergent photovoltaics technology in terms of research and development. Lead-based perovskite semiconductors exhibit unusual structural and electrical properties due to the chemical instability of Pb⁺² content. All-inorganic lead-free perovskites have become an alternative perovskite material for optoelectronic devices. However, high trap state density and the surface non-uniformity of the active layer make them inappropriate for high-performance photodetectors. Therefore, in this work, a feasible method for surface-passivation of all-inorganic lead-free perovskites with poly (3-hexylthiophene) (P3HT) as the photoactive layer for high-performance photodetectors is presented, and the underlain mechanisms to enhance device performance are investigated by experiments and simulation. As the result, the photoresponsivity of 1.56 A/W with a specific detectivity of 1.40 × 10¹⁴ Jones was obtained from photodetectors ITO/ZnO/CsSnBr₃:P3HT/CuSCN/Au under 0.1 mW/cm² 532 nm illumination in self-driven mode. Our experiments and simulation show that the enhanced-performance origins from both the enhanced transportation of the photogenerated charge carriers and the suppressed dark current through the device.