Fabrication of pentanary Cu(InGa)(SeS)2 absorbers by selenization and sulfurization

The objective of this study is to find the key factors to improve Voc. In this study, pentanary Cu(InGa)(SeS)2 absorbers were prepared by selenization and sulfurization or a sulfurization after selenization (SAS) method. It is found that the “sulfurization degree” defined as a function of temperature and holding time at the sulfurization step is a key factor to enhance the Ga diffusion and improve Voc. It is also verified that increase in the temperature difference between selenization and sulfurization enhances the incorporation of S into the selenide absorber. Applying these findings related to Ga and S, Voc of 642 mV/cell and efficiency of 14.3% are achieved on a 30 cm×30 cm-sized soda-lime glass substrate.