Jiaxiong Wang

Electrodeposition of In–Se and Ga–Se Thin Films for Preparation of CIGS Solar Cells

An approach was developed for electrochemical codeposition of In-Se and Ga-Se films with high repeatability and controllable In/Se and Ga/Se molar ratios to prepare precursor layers for copper indium gallium diselenide (CIGS) film formation by two-stage processes. Full potential of complexation was used for the first time by using aqueous electroplating solutions containing complexing agents at alkaline regime. It was found that tartrate and citrate were suitable complexing agents to solubilize In and Ga ions at high pH, respectively. Because no appreciable complexation of Se occurred, Se reduction potential could be independently controlled by the amount of dissolved Se. Use of alkaline solutions also reduced hydrogen bubble generation and related defects.

Electrochemical Co-deposition of In-Se and Ga-Se Thin Films for Preparation of CIGS Solar Cells

Electrochemical co-depositions of indium (In) with selenium (Se) and gallium (Ga) with selenium were carried out to obtain high-quality In-Se and Ga-Se films. The approach utilized full potential of complexation for the first time by using aqueous electroplating solutions containing complexing agents at alkaline regime. Complexing agents were employed to solubilize In and Ga ions at high pH and to bring their reduction potentials down, closer to that of Se. Since no appreciable complexation occurred between Se and the complexing agents, Se reduction potential could be independently controlled by the amount of dissolved Se. Tartrate and citrate were determined to be suitable complexing agents for In and Ga. By optimizing the concentrations of the metal salts, the complexing agents, the selenium source, pH and the electrodeposition current density, it was possible to obtain adherent and smooth In-Se and Ga-Se films with high repeatability and controllable In/Se and Ga/Se molar ratios.