Formation of CuInSe2 from Cu2Se and In2Se3 compounds

Chalcopyrite alpha-CuInSe2 (alpha-CIS) was prepared from mixed powders of Cu2Se and In2Se3 by annealing in the Se-and the non-Se environments. The mechanically ground powders were in an overall amorphous state. The mechanical alloying produced Cu3Se2 and CuSe compounds. At relatively low temperature, Cu3Se2 decomposed, Cu2-xSe and CuSe formed. The reaction for the formation of alpha-CuInSe2 occurred essentially at a temperature at similar to 350 degrees C in both the Se-and the non-Se environments. In the non-Se environment, reactions occurred by a solid-solid reaction and a certain amount of Se were released from the mixed powder, resulting in poor crystalline alpha-CuInSe2 powders. When annealed in the Se environment, low-melting Se-rich Cu-Se compounds were produced during reaction. The reactions occurred by a liquid-solid reaction above 450 degrees C. Large-grained and good crystalline quality of chalcopyrite CIS with near stoichiometric atomic ratio was obtained above 450 degrees C. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim