The Cu(In, Ga)Se2-ZnSe system: Optimizing solid solutions for high VOC photovoltaic devices

Solid solutions of CuInSe₂-ZnSe have recently shown promising potential as a photovoltaic material. In this work we investigate the CuInSe₂-ZnSe and CuGaSe₂-ZnSe systems for high V_oc photovoltaic applications. It was found that the highest V_oc (~740 mV) was achieved when the In/(In+Ga) ratio in the precursor was 0.13, i.e. very Ga-rich composition. Selenization conditions of CuZnGaIn metallic precursors were studied by changing reactive annealing parameters: temperature, dwelling time, temperature ramp and quantity of elemental Se. The optimal selenization parameters obtained in this study were: 550 °C, 30min, 20 °C/min and 50 mg of Se.