High-Gain Multispectral PVA/V2O5 Fibers/n-Si Heterojunction Photodetector with Self-Powered Operation and Long-Term Stability

Abstract In this work, poly(vinyl alcohol)/vanadium pentoxide (PVA/V2O5) composite fibers were fabricated by electrospinning and deposited onto n-type silicon (n-Si) to construct a heterojunction photodetector. The morphology and optical properties of the fibers were investigated by FE-SEM and UV–Vis spectroscopy, revealing an optical band gap of 3.09 eV. The fabricated PVA/V2O5@n-Si heterojunction exhibited pronounced rectifying behavior under dark conditions and a significant photocurrent enhancement with increasing white-light intensity (10–150 mW/cm2). At 10 mW/cm2, the device achieved an ON/OFF ratio of 104, a responsivity of 167 mA/W, and a detectivity of 2.7 × 1010 Jones. The photoresponse was further evaluated under 365, 590, and 850 nm illumination at 8 mW/cm2. Notably, the highest photosensitivity for all wavelengths was obtained at zero bias, with ON/OFF ratios exceeding 2700, demonstrating excellent self-powered operation capability. Under an optimum reverse bias of −2.0 V, the device reached a maximum responsivity of 2467 mA/W and a detectivity of 4.0 × 1011 Jones under 590 nm illumination. The results indicate that the PVA/V2O5@n-Si heterojunction exhibits broadband photodetection with superior performance in the visible region, highlighting its potential for high-performance and self-powered optoelectronic applications.