Synergistic Doping Strategy with Novel Multi-Carbonyl Conductive Polymer Enables Stable Self-Powered Perovskite Photodetectors

Lead halide perovskites hold immense promise for optoelectronic applications but still suffer from instability caused by defects. The defects are mainly generated from the film fabrication processes and halide ion migration during long-term storage. Here, a synergistic doping strategy is proposed to enhance the stability of perovskites. A novel multi-carbonyl conductive polymer, poly(benzodifurandione) (PBFDO), is incorporated into the precursor solution to effectively passivate the unoccupied Pb2+ defects in perovskite films and promote the continuous growth of perovskites. An organic iodide, thiophene-2-ethylammonium iodide (TEAI), is doped in the transport layer to inhibit the halide ion migration and enhance the stability of perovskites synergistically. Self-powered photodetectors are constructed with improved stability, maintaining approximate to 90% of their initial photocurrents after being stored for approximate to 87 days in a humid atmosphere with 60% relative humidity. The optimized photodetectors show a high detectivity of 8.1 x 1012 Jones at 680 nm wavelength, wide linear dynamic range of 121.9 dB, and fast response with a rise/fall time of 1.92/1.17 mu s. A reflection-mode perovskite photoplethysmography testing system is developed, achieving high heart rate testing capabilities. This work suggests the great potential of perovskite photodetectors for noninvasive medical monitoring applications.