Enhanced band gap energy and electrochromic behaviour of selenium incorporated copper thin film

Abstract

Selenium incorporated copper (CuSe) thin films are deposited on indium tin oxide (ITO) substrate by cyclic voltammogram of 5.0 ml of 0.1 M CuSO4 and 2 ml of 0.05 M selenium dioxide at potential range from -0.8 V to 0.7 V vs. Ag/AgCl in pH 1.0. The adherent nature, electroactivity and stability of the CuSe thin film were found to be good. The transmittance and absorption of thin films was analysed through UV-Vis spectra. An energy gap of 1.78 eV is obtained for CuSe thin films by extrapolating the linear portion of the curves hν versus (αhν)2. X-ray diffraction patterns revealed that the deposited films possess cubic structure with lattice constant (α) value 80.892Å. Surface morphology of thin film shows uniform granular mixed texture-like structure. The sizes of the grains are found to be in the range between 53.33 nm and 93.33 nm. The film composition was investigated using an energy dispersive X-ray (EDX) micro analytic unit attached with scanning electron microscope. The in-situ spectroelectrochemical behaviour of CuSe thin film at various applied potentials was observed in 0.1 M H2SO4. CuSe thin film exhibits dual colour chromic behaviour from contrast red colour to contrast yellows colour. The electrochromic device shows good optical contrast, coloration efficiency, response time and stability.