Compositional Engineering of Mixed-Cation Lead Mixed-Halide Perovskites for High-Performance Photodetectors

The mixed-cation lead mixed-halide perovskites can combine the advantages of the constituents while avoiding their drawbacks, and they have been widely explored in solar cells. However, there are only few research studies on the mixed-cation lead mixed-halide perovskites for photodetectors. In this work, we fabricate photodetectors based on FA(1–x)CsxPb(BryI(1–y))3 perovskite and reveal the effect of the chemical composition on the crystal phase stability and device performance of mixed-cation mixed-halide perovskite photodetectors. The FA0.7Cs0.3Pb(I0.8Br0.2)3 photodetectors exhibit high specific detectivity, high responsivity, and excellent stability in ambient conditions. Especially, the flexible perovskite photodetectors fabricated on poly(ethylene terephthalate) substrates exhibit extremely high specific detectivity of 2.8 × 1013 Jones, which is the highest value to date for flexible perovskite photodetectors, as well as excellent stability and outstanding flexibility. These results indicate that mixed-cation mixed-halide perovskites are promising to be applied in high-performance photodetectors and other flexible optoelectronic devices.