Phase, microstructural analysis, and humidity-sensing properties of orange dye and cuprous-oxide composite

Abstract

The effect of humidity on the phase, microstructure, and electrical properties of an organic compound orange dye (C17H17N5O2) and cuprous-oxide (Cu2O) micro-composite thin film has been investigated. 5 wt% commercially available orange dye and 30–40 wt% Cu2O were used to prepare an aqueous solution. The solution was layered in the form of a thin film on a pre-deposited copper glass substrate using a drop-casting technique under normal gravity conditions. A gap was made in the middle of the surface to get ohmic type electrodes at the ends of the glass substrate. In this way, a Cu/Cu2O–OD/Cu humidity sensor was fabricated. A self-made setup was used to carry out the experiment. Impedance of these samples was observed to decrease by 57–84 times and capacitance increased by 20–26 times with an increase in humidity from 62 to 98% RH. These observations demonstrated that impedance was more sensitive to the variations in humidity as compared to capacitance.