© 2021 Wiley-VCH GmbHThe development of high-performance, self-powered ultraviolet (UV) photodetectors (PDs) is of utmost interest for military and industrial applications. Herein, a novel design scheme for enhancing the performance of self-powered PDs based on the p–n heterojunction is proposed. The device architecture is engineered by integrating a nanostructured SnO2 layer into the n-SnO2/p-Si heterojunction. The resulting device yields an impressively high photoresponsivity of 22.73 A W−1, a large external quantum efficiency of 9065 %, and an outstanding detectivity of 1.57 × 1013 Jones at −5 V for 311 nm. Notably, the PDs possess self-powered characteristics with an extremely high photoresponsivity of 208 mA W−1 and detectivity of 1.17 × 1012 Jones toward 311 nm without any power supply, suggesting their high potential for future energy-efficient, self-powered, high-performance UV-detecting application.