2D Ruddlesden–Popper Perovskite with Ordered Phase Distribution for High‐Performance Self‐Powered Photodetectors

Abstract 2D Ruddlesden–Popper perovskites exhibit great potential in optoelectronic devices for superior stability compared with their 3D counterparts. However, to achieve a high level of device performance, it is crucial but challenging to regulate the phase distribution of 2D perovskites to facilitate charge carrier transfer. Herein, using a solvent additive method (adding a small amount of dimethyl sulfoxide (DMSO) in N , N ‐dimethylformamide (DMF)) combined with a hot‐casting process, the phase distribution of (PEA) 2 MA 3 Pb 4 I 13 (PEA + = C 6 H 5 CH 2 CH 2 NH 3 + , MA + = CH 3 NH 3 + ) perovskite can be well controlled and the Fermi level of perovskites along the film thickness direction can achieve gradient distribution. The increased built‐in potential, oriented crystal, and improved crystal quality jointly contribute to the high photoresponse of devices in the entire response spectrum range. The optimum device exhibits a characteristic detection peak at 570 nm with large responsivity/detectivity (0.44 A W −1 /3.38 × 10 12 Jones), ultrafast response speed with a rise/fall time of 20.8/20.6 µs, and improved stability. This work suggests the possibility of manipulating the ordered phase distribution of 2D perovskites toward high‐performance and stable optoelectronic conversion devices.