Environmentally Friendly Synthesis of Copper Zinc Tin Sulfide (CZTS) Thin Film Solar Cells: Advancing Sustainable Photo-Energy Conversion with Low-Temperature Chemical Processing

Efficient thin film solar cell technologies, including Cu(In,Ga)(S,Se)2 (CIGS) and CdTe-based cells, have advanced significantly. Yet, environmental concerns and element scarcity fuel the pursuit of alternatives. Copper zinc tin sulfide (Cu(Zn,Sn)(S,Se)2 or CZTS) garners attention for its use of non-toxic, abundant elements. We present a study on CZTS thin film solar cells via low-temperature chemical synthesis. The process involves dissolving Copper (II) acetate, zinc (II) acetate, and tin (II) chloride in 2-methoxyethanol and monoethanolamine to create a metal compound solution. This solution is spin-coated onto molybdenum-coated glass substrates and annealed at 300 degrees C. The CZTS layer is sulfurized at 400 degrees C using di-tert-butyl-disulfide (TBDS). Characterization utilized diverse Optimized compositions, Cu-poor and Zn-rich, vital for enhanced efficiency, were confirmed through energy-dispersive X-ray spectroscopy (EDX). X-ray diffraction (XRD) patterns aligned well with the kesterite phase, with additional phases like ZnS, SnS, SnS2, and CuS detected. X-ray photoelectron spectroscopy (XPS) offered insights into composition and surface contamination. High-resolution scans provided binding energies, validating the film's composition. This study enhances the comprehension and realization of CZTS thin film solar cells, offering a potential avenue for earth-abundant, efficient photovoltaics.