Substrate temperature-induced grain boundary reduction for high-efficiency self-powered n-V2O5/p-Si photovoltaic heterojunction devices

Correlated metal oxides are gaining prominence in photovoltaic research. In this context, vanadium oxide (VOx) is considered promising, yet high deposition temperatures limit its development for applications. We examine how substrate temperature affects the phases and crystallinity of VOx, particularly in n-type vanadium pentoxide and p-type silicon (n-V2O5/p-Si) heterojunctions, fabricated using pulsed laser deposition. Substrate temperature is crucial for tuning the V2O5 work function, significantly influencing device performance. Optimizing substrate temperature at 550◦C (H1) enhances photovoltaic efficiency, resulting in a self-powered output with a shortcircuit current of 􀀀 3.56 μA and an open-circuit voltage of ~200 mV, as well as a 244-fold improvement in the ON/OFF ratio under reverse bias. Responsivity peaks with green light at 515 nm, correlating with the 2.40 eV V2O5 bandgap identified via ultraviolet-visible spectroscopy. This setting also boosts carrier collection efficiency by 300 % compared to devices fabricated at 400◦C (H2). Our study reveals reduced grain boundary scattering and improved phase purity, essential for enhanced performance. This research demonstrates the potential of metal oxide heterojunctions in creating high-efficiency, tunable photovoltaic devices.