Transparent ZnO-nanowire-based device for UV light detection and ethanol gas sensing on c-Si solar cell

In this study, a transparent ZnO nanowire (NW)-based device for ethanol gas sensing and ultraviolet (UV) detection was fabricated and deposited onto an indium tin oxide/crystalline silicon (c-Si) solar cell. For UV detection, the photocurrent increased rapidly with a time constant of about 137 s when UV excitation was applied. The photocurrent decreased from 3 × 10^-6 to 1.2 × 10^-7 A when the UV light was switched off. For ethanol gas sensing, UV light was used to increase the quantity of O₂^- species. The ZnO sensor response increased from 8% to 21% when the ethanol gas concentration was increased from 50 to 150 ppm at 53 °C (heat generated by the c-Si solar cell). The sensor response approximately zero without solar illumination. The sensor had almost no effect on the transfer efficiency of the solar cell.