Flexible dual-heterojunction device design for high-performance photodetection and energy harvesting in self-powered visible light communication

Self-powered visible light communication (VLC) is attracting growing interest for its high-speed transmission, low power consumption, and sustainability. However, conventional optoelectronic converters struggle to combine efficient energy harvesting with high-performance photodetection. Herein, we propose a textured-Si-based dual-heterojunction device featuring self-supporting and flexible characteristics, capable of achieving high performance in both photodetection and energy harvesting for VLC applications. The designed device exhibits, at zero bias, a responsivity of 0.339 A W−1, a specific detectivity of 1.58 × 1013 Jones, and a response time of 20 ns under 467 nm illumination, alongside an energy conversion efficiency of 22.64% under white light-emitting diode irradiation. The underlying physical mechanisms for the excellent performances have been thoroughly investigated, revealing why the conventional photodetectors and solar cells cannot achieve these goals. This work demonstrates that the synergy between geometry and junction engineering enables strong absorption and efficient charge extraction, offering a theoretical design guideline for preparing high-performance self-powered VLC devices.