Self-Powered Perovskite Photon Counting Detectors with Extremely Low Dark Count Rate at High Temperatures

Here we show that polycrystalline perovskite photodetectors can count photons under zero bias at room or higher temperature with performance rivaling the commercial silicon photomultipliers (SiPMs) operating at a much higher bias. Different from perovskite solar cells, the photon counting capability of perovskite photon-counting detectors (PCDs) is mainly determined by shallow charge traps, despite that deep charge traps also limit charge collection efficiency. One main shallow defect level with energy depth of 5.8±0.8 millielectronvolt (meV) is identified in polycrystalline perovskites formed by one-step method, causing a high dark count rate (DCR) of >20,000 per second per square millimeter (cps/mm²) at room temperature. Perovskite films formed by two-step process with larger grain size have the 57.2±0.1 meV shallow traps which mainly locate at the film surface. We show that these very shallow traps can also be reduced by surface passivation using diphenyl sulfide, which dramatically suppresses DCR to 2 cps/mm², 1000 times better than SiPMs, and enables much better response linearity of perovskite PCDs to weak light. The superior photon-counting capability allows perovskite PCDs to collect gamma-ray spectra with better energy resolution than SiPMs. The perovskite PCDs can operate at high temperature of 85 ℃ without losing performance because of barely changed DCR at higher temperature, while SiPMs become much worse at higher temperature.