Radiation hardness and abnormal photoresponse dynamics of the CH₃NH₃PbI₃perovskite photodetector

The effects of proton irradiation on the electrical and optical properties of hybrid perovskite photodetectors have been investigated in this paper. Our results reveal that no significant changes in the photoelectric properties of the perovskite photodetectors are observed when the proton fluence accumulates to 1 × 10¹²p cm^-2. However, with further increase of proton fluence, the photoelectric conversion efficiency of the perovskite photodetectors begins to decrease notably. This can be attributed to the introduction of deep defect levels within the bandgaps of the CH₃NH₃PbI₃active layer and the phenyl-C61-butyric acid methyl ester (PCBM) layer after proton irradiation. Based on time-resolved photoluminescence measurements, the deep defect levels in the active layer behave as nonradiative recombination centers, resulting in a reduction of carrier lifetime. According to our first-principles calculations, the deep defect levels in the PCBM layer act as electron trap centers, leading to an accumulation of photo-generated electrons. Most interestingly, when the proton fluence reaches 1 × 10¹⁴p cm^-2, a transient inverse current in the perovskite photodetectors is observed after stopping illumination. This abnormal phenomenon is due to the accumulation and release of electrons trapped in the PCBM layer, which can diffuse to the perovskite active layer and form the inverse current.