Mechanical Synthesis of Cu₂SnS₃ (CTS) from Elemental Precursors for Photovoltaic Applications
Edgar Peduzine Orozco 1; Jair Melchor Robles 2; Abhishek Chandel 2; Sindi Horta Piñeres 1; Duber Ávila Padilla 1; Miguel Melendez Lira 2; Margarita Correa Vasquez 3.
1. Grupo de Óptica e informática, Departamento de Física, Química y Afines, Universidad Popular del Cesar, Diagonal 21 No. 29-56 Sabanas del Valle, Valledupar - Cesar, Colombia. 2. Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apdo. Postal 14-740, CDMX, 07000, México. 3. Grupo Física de Materiales, Departamento de Física, Universidad del Atlántico, Km 7 vía Puerto Colombia, Colombia.
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Abstract
Growing global energy demand, together with the need to reduce reliance on fossil fuels, has driven the search for more efficient, affordable, and sustainable photovoltaic technologies. However, some of the p-type semiconductors currently used as thin-film absorber materials are toxic, rely on scarce elements, or require costly fabrication processes, thereby limiting their industrial scalability. Against this backdrop, Cu₂SnS₃ (CTS) stands out as a promising absorber material, thanks to its tunable band gap, high optical absorption coefficient, and composition based on relatively abundant, low-toxicity elements. This work proposes a simple, fast, solvent-free mechanical milling synthesis route using elemental Cu, Sn, and S precursors and evaluates milling times of 3, 6, 9, and 12 h. The 12 h powders were then subjected to a sulfurization heat treatment under a controlled Ar atmosphere to promote CTS crystallization. SEM and EDS analysis showed powders with particle sizes on the order of micrometers and a composition close to stoichiometry (Cu₂SnS₃, 2:1:3) after 12 h of milling followed by heat treatment. Consistent with this, X-ray diffraction revealed the formation of Cu₂SnS₃ with coexisting cubic, monoclinic, and tetragonal phases, further confirmed by Raman spectroscopy through their characteristic vibrational bands. Additionally, optical analysis by UV-Vis diffuse reflectance, using the Kubelka–Munk method, allowed us to estimate a band gap energy of approximately 1.02 eV, consistent with values reported for photovoltaic absorber layers. These results demonstrate the feasibility of mechanical milling of elemental precursors followed by a sulfurization heat treatment as a direct and potentially scalable route to obtaining Cu₂SnS₃. Furthermore, they provide insight into the structural evolution of the material as a function of milling time and support its potential for photovoltaic applications.
Keywords: Mechanical milling; Cu₂SnS₃; Photovoltaic materials