Effect of Zn on nanoscale quaternary Cu2ZnSnS4 thin film electrodes for high performance supercapacitors

Abstract Nanostructured Cu2ZnSnS4 thin films have been deposited with different Zn concentrations by successive ionic layer adsorption and reaction (SILAR) method. The powder X-ray diffraction patterns have been confirmed the tetragonal structure of the Cu2ZnSnS4 film with the presence of wurtzite and kesterite phase. Scanning electron microscope attached with energy dispersive X-ray analyzer (EDX) has used to identify the existence of spherical morphology and confirmed the elemental composition present in the prepared films. The uniform distribution and rough surface of the film have been confirmed by atomic force microscopic (AFM) images. Tauc's plot have plotted and used to calculate the optical band gap of the films. The band gap obtained between 1.47 and 1.92 eV for different zinc concentrations. The optimized film has been examined by photo-electrochemical technique and the efficiency obtained as 1.678%. The electrochemical performances such as cyclic voltammetry, Galvanostatic charge-discharge and electrical impedance spectroscopy have been analyzed using the optimized film as a working electrode. This study resulted in maximum specific capacitance as 165.04 F g−1 at the current density 1 A g−1.