Fast-Response and Stable Self-Powered Phenylethylammonium-Based Quasi-Two-Dimensional Perovskite Photodetectors Enabled by a Highly Oriented Crystal Growth Strategy

Phenylethylammonium (PEA) organic spacer-based quasi-two-dimensional (Q-2D) perovskites have garnered considerable attention due to their tunable optoelectronic properties and high environmental stability. However, the response speed and responsivity of PEA-based Q-2D perovskite photodiodes (Q-2D PPDs) remain limited by inadequate carrier transport and collection. Herein, we propose a simple yet effective crystal orientation control strategy to overcome these limitations. Compositional engineering of the photoactive layer is employed to suppress defect formation and promote out-of-plane crystal orientation, which facilitates carrier transport in vertical n–i–p photodiodes. Concurrently, the optimized surface morphology of the Q-2D perovskite film enables the implementation of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) as a hole transport layer to enhance hole extraction, block interfacial electron injection, and reduce dark leakage current. Our self-powered Q-2D PPDs, featuring a device architecture of ITO/SnO2/(4F-PEA)2(MA)3Pb4I11Cl2/PTAA/Au, exhibit ultrafast response times of 2.5 μs/1.9 μs (rise/fall), a responsivity of 0.25 A/W, and a detectivity of 3.4 × 1012 Jones at 550 nm. Notably, the unencapsulated detectors show excellent operational stability for over 180 days under ambient conditions. The remarkable detection performance of the Q-2D PPDs was further demonstrated in image sensing and indirect X-ray detection, showcasing their potential for versatile optoelectronic applications.