Sulfurization temperature dependence of Na-added Cu₂SnS₃ thin films prepared on an alkali-free substrate

Abstract

CTS thin films were prepared via the sulfurization of Sn/Cu stacked precursors at 500-600 ℃. The observation of the surface morphology of the CTS thin film revealed that the CTS crystal grain size increased at ≥560 ℃. It was confirmed that the monoclinic phase of the CTS thin film becomes more abundant as the sulfurization temperature increases, and that the CTS thin film completely acquires a monoclinic structure at ≥570 ℃. The CTS thin-film solar cell can obtain good photovoltaic characteristics by forming a monoclinic-structured single phase and by increasing the crystal grain size.