Fabrication and study of H2O-incorporated zinc-phosphate films interfaced with organic dye and their photo-detection characteristics

Abstract

This study explores the hydrothermal growth of zinc-phosphate-hydrate (ZPH) films and their application in dye-based photovoltaic sensors. ZPH films grown on electrically conductive ITO substrates exhibit a layered morphology with interlayer distances of ∼20–30 nm. Their light emission spectrum is dominated by a narrow UV band at 378 nm, with a full width at half maximum of 16 nm. Photoluminescence excitation data reveal a sharp cutoff edge at ∼447 nm, corresponding to a bandgap of 2.77 eV. When interfaced with anthocyanin dye, the ZPH films generated a photovoltage of up to 281 mV under white light illumination, with the electrolyte enhancing the rate of photogenerated charge transfer. Under repeated on/off illuminations and steady state, a zero-bias photo-to-dark current ratio approached 97.5, with photocurrent rise and decay constants of ∼0.4 and 10.8 s, respectively. These findings confirm that ZPH-based inorganic–organic interfaces, akin to conventional semiconductor junctions, hold strong potential for low-cost photovoltaics and self-powered UV–visible photodetectors operating in the sub-kHz frequency range.