Dependence of photoluminescence on sulfurization temperature of Cu2SnS3 thin films

The dependence of photoluminescence (PL) on sulfurization temperature of the Cu 2 SnS 3 (CTS) thin films was investigated. CTS thin films were prepared at various sulfurization temperatures in the range of 500–600 ℃, and differences in the conversion efficiency of solar cells with the CTS thin films as absorption layer and the crystal structure of the CTS thin films were observed. In low-conversion-efficiency CTS films, which were a mix of monoclinic and cubic crystals, the PL spectrum only showed donor–acceptor pair (DAP) recombination luminescence due to deep defects. In high-conversion-efficiency CTS thin films, which contained only monoclinic crystals, the PL spectrum showed DAP recombination luminescence originating from the same deep defects. In addition band-edge luminescence was observed at room temperature. Thus, it was found that the conversion efficiency and crystal structure of CTS thin film can be easily estimated from PL measurements.