Synthesis of CIGS absorber layers via a paste coating

CuInxGa1−xSe2 (CIGS) thin films were prepared by a paste coating with the aim of developing a simpler and the lower cost method for fabricating the absorber layers of thin film solar cells. In particular, a paste of a Cu, In, Ga, and Se precursor mixture was first prepared, followed by a reaction between them at elevated temperatures after depositing the paste onto a glass substrate. No apparent change in composition was observed during thermal annealing at 450 °C in the absence of a gas-phase selenium source. A pre-annealing process at 250 °C under ambient conditions performed before annealing (450 °C) under reduction conditions reduced the level of carbon deposition in/on the films without perturbing the stoichiometry of the CIGS thin films.