Kesterite Cu₂ZnSnS₄ (CZTS) has emerged as a promising absorber layer in thin-film solar cells due to its earth-abundant, environmentally benign constituents and suitable optical properties. However, the highest conversion efficiency of 12.6% for Se-alloyed CZTS (CZTSSe) films has been achieved using hydrazine-based slurry, which poses significant safety and environmental hazards. This thesis explores the potential of ethanol-based homogeneous solutions for the direct solution coating of CZTS films via dip coating. Ethanol, being an environmentally friendly solvent, offers rapid evaporation, minimizing residual impurities in the films. This approach facilitates better stoichiometric control and eliminates the need for pre-fabrication and stabilization of CZTS particles, presenting an efficient alternative for solar cell fabrication.
The study highlights the critical role of grain boundaries in influencing the performance of CZTS solar cells. Positive surface potentials at grain boundaries enhance minority carrier collection through band bending, but high recombination losses at these sites limit overall efficiency. Advanced passivation techniques and optimized fabrication conditions are essential to mitigate recombination losses and improve device performance. The research also investigates the effects of post-deposition high-temperature annealing (HTA) in a sulfur environment, identifying optimal settings for phase-pure CZTS film formation. The findings underscore the importance of controlling the sulfur vapor flux during HTA to promote kesterite growth and prevent decomposition. Additionally, strategies for producing larger grains with fewer boundaries are explored to further enhance the power conversion efficiency of CZTS-based solar cells, paving the way for the advancement of cost-effective and environmentally sustainable photovoltaic technologies.