A Partially Ion-Exchanged Perovskite Single-Crystal Heterojunction for Self-Powered Photodetection

Heterojunctions, characterized by built-in electric fields and efficient charge-carrier separation, represent a promising architecture for high-performance perovskite photodetectors (PDs). Unlike traditional template methods, the confined ion-exchange strategy described here operates directly on high-quality single-crystal (SC) wafers, offering significant technical advantages for heterojunction device fabrication. Leveraging spatial confinement effects, this method enables precise component gradient regulation while effectively circumventing the interface defects and structural damage typically associated with template synthesis and postremoval processes. Notably, this approach features strong process compatibility, allowing seamless integration with existing semiconductor technologies, and high system universality, making it applicable to diverse perovskite systems. Under a forward bias of 5 V, the resulting heterojunction PD exhibits good performance, with a responsivity (R) of 9.9 A/W, specific detectivity (D) of 2.58 × 1012 Jones, external quantum efficiency (EQE) of 3038%, and linear dynamic response (LDR) of 109.2 dB. Even under self-powered conditions, the PD maintains R of 0.143 A/W, D of 2.21 × 1011 Jones, EQE of 43%, and LDR of 102.7 dB. The confined ion-exchange method proposed herein provides a universal solution with significant potential for the large-scale chemical preparation of heterojunction devices.