Hsing-I Hsiang, a, , Li-Hsin Lua, Yu-Lun Changa, Dahtong Raya and Fu-Su Yena
The reaction mechanism and CuInSe2 formation kinetics using a solid state reaction from Cu2Se and In2Se3 powders synthesized using a heating up process were investigated using X-ray diffractomy (XRD) and transmission electron microscopy (TEM). It was observed that the CuInSe2 phase increased gradually, accompanied with a decrease in γ-In2Se3 with no intermediate phase as the calcination temperature and soaking time were increased. The reaction kinetics was analyzed using the Avrami and polynomial kinetic model, suggesting that CuInSe2 formation from Cu2Se and In2Se3 powders follows a diffusion-controlled reaction with an apparent activation energy of about 122.5–182.3 kJ/mol. Cu2Se and In2Se3 phases react and directly transform into CIS without the occurrence of any intermediate phase and the size of the newly formed CuInSe2 crystallites was close to that of the Cu2Se reactant particle based on the TEM results, which indicated that the solid reaction kinetics may be dominated by the diffusion of In3+ ions.