High-efficiency self-powered perovskite photodetector with an electron-enhancing SnO2/WS2 double electron transport layer

Abstract

In this study, we report the enhancement of device performance based on perovskite photoactivity using a SnO₂/WS₂ double electron transport layer (ETL). The WS₂ nanosheet was inserted to minimize the energy loss at the interface between the SnO₂ ETL and perovskite absorber layer by the preparation of a smooth perovskite film. The hydrophobic WS₂ layer coating on the SnO₂ nanoparticles provides a uniform and high-quality perovskite layer without pinholes. Increased contact angle measurement confirmed that after the insertion of the SnO₂/WS₂ double ETL, the surface property changes towards hydrophobic, compared to the bare SnO₂ layer. Moreover, by matching the energy level between the perovskite and SnO₂ ETL, the introduction of the WS₂ nanosheet leads to better carrier transport and extraction. The pinhole-free perovskite film and well-matched energy level are responsible for the perovskite-based photodetector with a SnO₂/WS₂ double ETL demonstrating simultaneous improvement of the responsivity and specific detectivity of the SnO₂/WS₂, which are increased by 4.2 and 2.1 times under UVC, 4.7 and 2.2 times under UVB, and 6.4 and 2.6 times under UVA regions, respectively, compared to those of the PD without an ETL. Our results suggest guidelines for an interface engineering strategy to improve perovskite optoelectronic device performance.