Dipole-Mediated Interfacial Engineering for Enhanced Built-In Driving Force in Quasi-2D Perovskite Self-Powered Photodetectors

Self-powered photodetectors (SPPDs), operating without an external bias, hold significant potential for next-generation optoelectronic systems. Their performance, however, is intrinsically constrained by the heterojunction interface, since charge extraction depends solely on the built-in potential. Here, we report a strategy to enhance the built-in potential and device performance in quasi-2D perovskite (PVK)-based SPPDs through energy landscape engineering at the heterojunction interface. By incorporating self-assembled molecules (SAMs) onto a hole transport layer (HTL), we achieve suppression of low- n phase of quasi-2D PVK, reduced interfacial recombination, and an enhanced built-in electric field. Systematic characterization reveals that the SAM promotes favorable energy alignment, passivates interfacial defects, and promotes improved PVK film growth. The SPPDs exhibit a high responsivity of 0.373 A/W, a specific detectivity of 8.34 × 10 12 Jones at 560 nm, and an external quantum efficiency exceeding 70% across wavelengths of 460–610 nm with a peak of 82% at 560 nm. Furthermore, the devices demonstrate rapid response times of 7.25/3.68 μs and improved operational stability, retaining 96.4% of their initial performance over 4200 h. This work demonstrates interfacial energy landscape engineering as an effective strategy for improving the potential of quasi-2D PVKs for self-powered optoelectronic devices.