Electrodeposition And Characterization Of CuInSe₂ Thin Films

CuInSe₂ is a highly promising semiconductor material for thin film solar cells, which possesses direct and tunable energy band gap and extraordinarily high absorption coefficient,high photoelectric conversion efficiency and long-term stability without any signs of degradation.Electrodeposition has attracted much attention for its low-cost,good quality,large area,continuous processing and low temperature preparation.CuInSe₂ polycrystalline thin films were grown on ITO/soda-lime glass using an electrodeposition process in a potentiostatic system.The electrolyte consisted of CuCl₂,InCl₃,H₂SeO₃ and Sodium citrate,with dilute HCl solution adjusting its pH. The performance of as-deposited films was enhanced after selenization.The CuInSe₂ films were characterized by SEM/EDS,XRD,Raman spectroscopy and profiler for structure and composition analysis.By adjusting the concentration of InCl₃ and complexing agent Sodium citrate,the films with nearly stoichiometfic ratio can be prepared in one-step electrodeposition. The formation of intermediate phases of CuInSe₂ such as Cu₃Se₂ and In₂Se₃ was found in as-deposited films.These phases disappear after selenizing at high temperature,as the react together to form a single phase of CuInSe₂,and also made the films very good crystallization.The best parameter and selenizing process in our experiments is:the electrolyte with 5mM CuCl₂,20mM InCl₃,8mM H₂SeO₃ and 0.5M Sodium citrate,pH 1.8,applied potential—0.7V vs SCE;selenizing in Se atmosphere at 500℃for 20 minutes.