Ion Migration in the All-Inorganic Perovskite CsPbBr₃ and Its Impacts on Photodetection

Abstract

Ion migration has been widely investigated in the lead halide perovskites, which severely deteriorates the performance of solar cells. However, the impacts of ion migration on photodetection have been rarely studied so far. In the current work, ion migration in the all-inorganic perovskite CsPbBr3 and its impacts on photodetection have been investigated in detail. Electrical property studies showed that ion migration has occurred under an external electric field poling, which led to the formation of a pn-junction within the CsPbBr3 single crystals. Density function theory calculations have shown that vacancy-assisted Br-ion migration dominated the ion transportation processes. Accordingly, the Au/CsPbBr3/Au metal–semiconductor–metal structured photodetectors showed a decreased performance in terms of a decreased on–off ratio and decreased detectivity through a long-term operation under a bias voltage, although the photoresponsivity slightly increased simultaneously. The results provided in this work verify the negative effects of ion migration in the all-inorganic perovskite CsPbBr3, which may account for the instability of CsPbBr3-based optoelectronic devices reported in the literature.