Optimizing photovoltaic performance in CZTS-Based Zn(1-x)SnxO (x=0.100, 0.133, 0.167, 0.200 and 0.233) thin film solar cells: A structural, morphological and optical study

Recently, the trend in solar cell research has become highly competitive, with researchers striving to find the best material that strikes a balance between various factors, including fabrication speed, cost, material toxicity, abundance, and overall photovoltaic performance. Typically, cadmium sulfide serves as the buffer layer in CZTS solar cells, but this material is known for its high toxicity. On the other hand, zinc tin oxide (ZTO) has gained popularity in solar cell applications due to its transparency, conductivity, thermal stability, and non-toxic nature. Consequently, the idea of using ZTO as an alternative buffer layer in CZTS solar cells has emerged. In this study, we synthesized nanocomposite thin films of Zn(1−x)SnxO (x = 0.100, 0.133, 0.167, 0.200, and 0.233% w/w) using the sol–gel method and spin coating technique. Among the various concentrations tested, the thin film composed of Zn0.833Sn0.167O demonstrated the highest power conversion efficiency (PCE) of 0.54%. This outcome marked a successful result, indicating that this particular composition optimizes efficiency in our study. It is noteworthy that excessive tin doping did not lead to improved efficiency. However, it is important to acknowledge that the PCE in our experiment is relatively low compared to that of other researchers due to the use of ITO glass as the back contact, chosen for economic considerations. Furthermore, our fabrication method for ZTO thin films resulted in a bandgap energy (Eg) value of 0.78 eV. In summary, our findings suggest that ZTO has the potential to replace cadmium sulfide as the buffer layer in CZTS-based solar cells. These findings are expected to have a significant impact on promoting ZTO as the primary buffer material in CZTS solar cell technology.