Phase Transformation of CuInxGa1-x-Se2 Powder by Milling and Heat Treatment

Abstract

CuIn_xGa_1-x-Se₂ ink and paste by milling and subsequent heat treatment to remove organic compounds contained in the thick film are to be crucial to produce dense CuIn_xGa_1-x-Se₂ absorber layer, however, few studies has been performed to address such processes. The object of this study is to identify wet milling conditions for CuIn_xGa_1-x-Se₂ powder and observe its phase transition and pertinent morphology change according to different heat treatments of CuIn_xGa_1-x-Se₂. CuIn_xGa_1-x-Se₂ powder was dispersed in planetary mill containing diethylamine as solvent and exhibited no phase transformation. CuIn_xGa_1-x-Se₂ disappeared after annealed in air at 200 ºC or more. In the case of Se-N₂-H₂ atmosphere, secondary phase in small portion was formed after annealed at 150 ºC up to 300 ºC whereas CuIn_xGa_1-x-Se₂ was maintained above it. Dense CuIn_xGa_1-x-Se₂ film was obtained after sintered in Se-H₂-N₂ at 800 ºC.