Tunable interfacial engineering of 2D PbI2 Schottky photodetectors via dissimilar contacts toward self-powered encrypted communication

Two-dimensional (2D) PbI2 offers significant potential for high-performance optoelectronics due to its unique excitonic properties and superior carrier mobility, while complex interfacial charge kinetics and reliance on external bias hinder its application in energy-efficient applications. To address these challenges, we first elucidate the modulation effects of Schottky contacts on carrier transport through interfacial engineering across different metal electrodes, establishing a high-gain performance benchmark with gold contacts. Furthermore, a symmetry-breaking strategy via geometric engineering is proposed for realizing the transition from material-dependent Schottky depletion to structure-induced built-in field regulation, enabling self-powered operation. Theoretical and experimental analyses confirm that the spatial imbalance of depletion regions, triggered by the asymmetric contact geometry, generates a macroscopic net built-in field that facilitates efficient carrier separation and extraction. At an optimized area ratio of 1 : 6 under 405 nm illumination, the self-powered device achieves an on/off ratio of 6 × 104, a detectivity of 8 × 1010 Jones, a linear dynamic range of 96 dB, and a rapid response time of 60 ms. Finally, a high-fidelity ASCII-encoded encrypted communication system is demonstrated, providing an innovative physical paradigm for energy-autonomous IoT sensing and secure communication technologies.