Self-powered perovskite photon-counting detectors

Metal-halide perovskites (MHPs) have been successfully exploited for converting photons to charges or vice versa in applications of solar cells, light-emitting diodes and solar fuels(1-3), for which all these applications involve strong light. Here we show that self-powered polycrystalline perovskite photodetectors can rival the commercial silicon photomultipliers (SiPMs) for photon counting. The photon-counting capability of perovskite photon-counting detectors (PCDs) is mainly determined by shallow traps, despite that deep traps also limit charge-collection efficiency. Two shallow traps with energy depth of 5.8 +/- 0.8 millielectronvolts (meV) and 57.2 +/- 0.1 meV are identified in polycrystalline methylammonium lead triiodide, which mainly stay at grain boundaries and the surface, respectively. We show that these shallow traps can be reduced by grain-size enhancement and surface passivation using diphenyl sulfide, respectively. It greatly suppresses dark count rate (DCR) from >20,000 counts per second per square millimetre (cps mm(-2)) to 2 cps mm(-2) at room temperature, enabling much better response to weak light than SiPMs. The perovskite PCDs can collect gamma-ray spectra with better energy resolution than SiPMs and maintain performance at high temperatures up to 85 degrees C. The zero-bias operation of perovskite detectors enables no drift of noise and detection property. This study opens a new application of photon counting for perovskites that uses their unique defect properties.

Automated summary

Metal-halide perovskites have been used in various applications such as solar cells, LEDs, and solar fuels to convert photons to charges or vice versa. In this study, we demonstrate that self-powered polycrystalline perovskite photodetectors can match the performance of commercial silicon photomultipliers for photon counting. The photon-counting capability of these detectors is primarily determined by shallow traps, which can be reduced by grain-size enhancement and surface passivation using diphenyl sulfide.