Optimization of the Selenization Temperature on the Mn-Substituted Cu2ZnSn(S,Se)(4) Thin Films and Its Impact on the Performance of Solar Cells

Cu2ZnSn(S,Se)(4) (CZTSSe) films are considered to be promising materials in the advancement of thin-film solar cells. In such films, the amounts of S and Se control the bandgap. Therefore, it is crucial to control the concentration of S/Se to improve efficiency. In this study, Cu2MnxZn1-xSnS4 (CMZTS) films were fabricated using the sol-gel method and treated in a Se environment. The films were post-annealed in a Se atmosphere at various temperature ranges from 300 degrees C to 550 degrees C at intervals of 200 degrees C for 15 min to obtain Cu2MnxZn1-xSn(S,Se)(4) (CMZTSSe). The elemental properties, surface morphology, and electro-optical properties of the CMZTSSe films were investigated in detail. The bandgap of the CMZTSSe films was adjustable in the scope of 1.11-1.22 eV. The structural propeties and phase purity of the CMZTSSe films were analyzed by X-ray diffraction and Raman analysis. High-quality CMZTSSe films with large grains could be acquired by suitably changing the selenization temperature. Under the optimized selenization conditions, the efficiency of the fabricated CMZTSSe device reached 3.08%.