Formation Mechanisms of Cu(In0.7Ga0.3)Se2 Nanocrystallites Synthesized Using Hot-Injection and Heating-Up Processes

Nearly monodispersed CuIn0.7Ga0.3Se2 (CIGS) nanocrystals were successfully prepared using the thermal decomposition of copper, indium (In), gallium (Ga), and selenium–oleylamine (OLA) complexes via the heating‐up process. The phase formation sequence was CuSe→CuInSe2→CIGS. The CIGS nanocrystals synthesized using the heating‐up process exhibited a single chalcopyrite phase and its chemical composition was close to stoichiometric. However, phase separation of the In‐rich and Ga‐rich phases was found using the hot‐injection method due to the difference in reactivity between In–OLA and Ga–OLA complexes.