High‐Performing Quasi‐2D Perovskite Photodetectors with Efficient Charge Transport Network Built from Vertically Orientated and Evenly Distributed 3D‐Like Phases

Abstract Quasi‐two‐dimensional (Q‐2D) perovskites are emerging as one of the most promising materials for photodetectors. However, a significant challenge to Q‐2D perovskites for photodetection is their insufficient charge transport ability, which is mainly attributed to their hybrid low‐dimensional n ‐phase structure. This study demonstrates that evenly‐distributed 3D‐like phases with vertical orientation throughout the film can greatly facilitate charge transport and suppress charge recombination, outperforming the prevalent phase structure with a vertical dimension gradient. Based on such a phase structure, a Q‐2D Ruddlesden−Popper perovskite self‐powered photodetector achieving a combination of exceptional figures‐of‐merit is realized, including a responsivity of 0.45 AW −1 , a peak specific detectivity of 2.3 × 10 13 Jones, a 156 dB linear dynamic range, and a rise/fall time of 2.89 µs/1.93 µs. The desired phase structure is obtained by utilizing a double‐hole transport layer (HTL), combining hydrophobic PTAA and hydrophilic PEDOT: PSS. Besides, the dependence of the hybrid low‐dimensional phase structure is also identified on the surface energy of the buried HTL substrate. This study gives insight into the correlation between Q‐2D perovskites’ phase structure and performance, providing a valuable design guide for Q‐2D perovskite‐based photodetectors.