High-Performance UV–Visible Dual-Band Self-Powered Photodetector Based on ZnO/BFZO/P3HT Heterojunction for Logic Gates and Encrypted Communication

The growing demand for broadband self-powered photodetectors has spotlighted BiFeO 3 (BFO) as a promising candidate due to its narrow bandgap. However, its practical application remains limited by a low photocurrent and poor responsivity in the visible-light region. In this work, a novel n-ZnO/i-BFZO/p-P3HT heterojunction was designed based on Zr 4+ -doped BFO (BFZO) and low-bandgap P3HT. Zr 4+ doping effectively suppresses intrinsic defects in BFO, while P3HT broadens visible-light absorption and facilitates efficient hole extraction. The resulting heterojunction enables efficient charge generation, spatial separation, and directional carrier transport across the UV–vis spectrum. Under 365 nm illumination, it achieves a photocurrent of 1.04 mA/cm 2, representing an enhancement of 27% over that of its undoped counterpart. A maximum responsivity of 15.52 mA/W and a specific detectivity of 4.35 × 10 10 Jones are obtained, with fast response/recovery times of 0.8/2.2 ms, respectively. Under white light illumination, the maximum responsivity and detectivity reach 4.00 mA/W and 2.00 × 10 10 Jones, respectively, approximately 0.9 and 2.1 times higher than those of the ZnO/BFZO/NiO reference device. These performance enhancements are attributed to the synergistic effects of Zr 4+ -induced defect passivation, P3HT-mediated visible-light absorption, and the optimized n-i-p heterojunction configuration. The demonstrated dual-band photodetection capability highlights the potential of the ZnO/BFZO/P3HT device for integration in photonic logic gates and secure optical communication technologies.