SnOx-doped TiOx Thin Films by Reactive Magnetron Sputtering: A Promising Electron Transport Layer for Perovskite Solar Cells

Perovskite solar cells (PSCs) have emerged as the most promising photovoltaic technology. For the first time in the history of photovoltaics, efficiency of a solar cell technology has grown by more than 22 % (from 3.8% in 2009 to 26.7% in 2024 for single junction) in less than two decades [1] [2]. While TiO2 and SnO2 are leading materials as electron transport layers in hybrid halide perovskites, investigations on the synergistic properties of thin layers prepared by chemical methods or physical vapor deposition is limited. In this work, we have investigated TiOx and SnOx-doped TiOx thin films of similar thickness deposited on FTO substrates by reactive magnetron sputtering at 225°C for two working pressures (3.4×10-3 and 30×10-3 Torr). The structural properties of the films were obtained using X-ray diffraction and Raman spectroscopy, and the optical and electrical properties were analyzed by UV-Vis diffuse reflectance and the four-point probe method, respectively. The results show that the incorporation of appropriate amounts of SnOx in TiOx thin-films at 3.4×10-3 Torr decreased the resistivity from 43 to 0.41 Ω.cm, and increased the transmittance by more than 10 %. This highlights the potential of SnOx-doping on TiOx films as electron transport layers to enhance the efficiency of hybrid halide perovskite solar cells. [1] M. Afroz, R. K. Ratnesh, S. Srivastava, and J. Singh, "Perovskite solar cells: Progress, challenges, and future avenues to clean energy," Sol. Energy, vol. 287, p. 113205, 2025. [2] "Interactive Best Research-Cell Efficiency Chart." Accessed: Mar. 13, 2024. [Online]. Available: https://www.nrel.gov/pv/interactive-cell-efficiency.htm