Performance optimization of solution-based Cu₂SnS₃ thin-film solar cells via sulfurization process

Abstract

Thin-film solar cells, particularly those which are earth-abundant and non-toxic, present a promising solution to the growing global energy demand by offering sustainable, cost-effective, and environmentally friendly alternatives to conventional silicon-based photovoltaic technologies. In this study, we focus on Cu₂SnS₃ (CTS) thin films, fabricated using the sol–gel technique, to address efficiency challenges by exploring the impact of varying sulfurization times and annealing temperatures on film quality and device performance. Glass substrates were prepared and spin-coated with a precursor solution, followed by drying and sulfurization using Rapid Thermal Processing (RTP) at temperatures of 500 °C, 525 °C, and 550 °C for 1 min. Then, sulfurization time (1, 3, 5 min.) was investigated at 525 °C sulfurization temperature. Comprehensive characterization, including XRD, Raman spectroscopy, and SEM, was conducted to analyze the structural, morphological, and optical properties of the films. Results indicated that a sulfurization temperature of 525 °C for 3 min yielded the most desirable crystal size, strain values, and a homogeneous monoclinic structure. The best-performing CTS solar cells achieved a conversion efficiency of 2.1% under these optimal conditions. The photovoltaic performance of the fabricated CTS solar cells, assessed through conversion efficiencies under varying sulfurization conditions, underscores the critical role of sulfurization time and temperature in optimizing CTS thin films, ultimately aiming to narrow the gap between experimental and theoretical efficiency limits.