Photodetectors as a significant unit of intelligent optoelectronic systems have stimulated immense attention from multidisciplinary areas. Photomultiplication (PM) is desirable for sensitive photodetectors with strong detection capability of weak light, which can further simplify the photo‐detection systems without pre‐amplifier circuit. For organic photodetectors (OPDs), PM phenomenon cannot be realized by utilizing the principle of avalanche effect or impact ionization as in inorganic materials, stemming from organic semiconductor materials with large exciton binding energy and disordered structure. In this review, the recent progress on PM type OPDs is comprehensively summarized from the perspective of device physics and material science. Charge tunneling injection induced by interfacial traps becomes the mainstream working mechanism for obtaining PM phenomenon. A series of PM type OPDs was achieved by utilizing interfacial blocking layer and introducing trap states into active layer or interfacial layer. The filter‐free PM type narrowband OPDs are realized by combining the concept of charge injection narrowing with the mechanism of PM. Meanwhile, further development on this hot topic is proposed and fully discussed, including multifunctional OPDs, organic–inorganic hybrid photodetectors, and photodetector systems.
It is a great challenge to obtain broadband response perovskite photodetectors (PPDs) due to the relatively large bandgaps of the most used methylammonium lead halide perovskites. The response range of the reported PPDs is limited in the ultraviolet-visible range. Here, highly sensitive PPDs are successfully fabricated with low bandgap (≈1.25 eV) (FASnI 3 ) 0.6 (MAPbI 3 ) 0.4 perovskite as active layers, exhibiting a broadband response from 300 to 1000 nm. The performance of the PPDs can be optimized by adjusting the thicknesses of the perovskite and C 60 layers. The optimized PPDs with 1000 nm thick perovskite layer and 70 nm thick C 60 layer exhibit an almost flat external quantum efficiency (EQE) spectrum from 350 to 900 nm with EQE larger than 65% under −0.2 V bias. Meanwhile, the optimized PPDs also exhibit suppressed dark current of 3.9 nA, high responsivity (R) of over 0.4 A W −1 , high specific detectivity (D*) of over 10 12 Jones in the near-infrared region under −0.2 V. Such highly sensitive broadband response PPDs, which can work well as self-powered conditions, offer great potential applications in multicolor light detection.
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