Phase transformation and grain growth in spray deposited wurtzite CuInS2 films

We report the processing of large-grained chalcopyrite-CuIn(S,Se)2 (ch-CISSe) films using spray deposition of wurtzite-CuInS2 (wz-CIS) nanoparticle ink and subsequent selenization. Wurtzite to chalcopyrite phase trans-formation and grain growth were studied at varying selenization temperatures of 350, 400, 450, 500 and 550 degrees C for 15 min. On annealing in selenium (Se) atmosphere at 400 degrees C, the film transformed from wurtzite to chal-copyrite phase completely, while the grain growth took place at higher temperatures (500-550 degrees C), requiring greater amounts of Se substitution (Se/Se + S > 0.7). Differential scanning calorimetry (DSC) indicates that the phase transformation temperature is sensitive to the heating rate and has a second-order character.

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We report the processing of large-grained chalcopyrite-CuIn(S,Se)2 (ch-CISSe) films using spray deposition of wurtzite-CuInS2 (wz-CIS) nanoparticle ink and subsequent selenization. The transformation from wurtzite to chalcopyrite phase and grain growth were studied at different selenization temperatures. It was found that at the suitable selenization temperature and time, the film can completely transform into chalcopyrite phase and the grains can grow.