The fabrication of self-powered P-I-N perovskite photodetectors with high on-off ratio using cuprous thiocyanate as hole transport layer

In this study, a two-step method was used to prepare CsPbBr₃ perovskite thin films. The first step is to spin-coat PbBr₂ solution on the ITO substrate, and the second step is to soak CsBr solution with different soaking times. The structure of the proposed films is gradually changing from CsPb₂Br₅ to CsPbBr₃ as the soaking times increase. The self-powered UV photodetector with P-I-N structure is fabricated with structure configuration of ITO substrate/ZnO seed layer/ZnO nanorod/CsPbBr₃/CuSCN/Ag. Diethyl sulfide (DES) is used as solvent for preparing CuSCN solution, and different DES removal methods on the device's performance is investigated. In terms of device performance, the response time is less than 10 ms; the responsivity is partially increased from 410 mA/W to 530 mA/W, and the lowest dark current reaches 1.28 × 10⁻¹² A which increases the on/off ratio to 4.2 × 10⁶. The proposed devices show high on/off under zero-bias condition, as compared to the reported data.