Radiation hardness and abnormal photoresponse dynamics of the CH3NH3PbI3 perovskite 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 × 1012 p 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 CH3NH3PbI3 active 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 × 1014 p 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.