Compact Layer-Free Perovskite Solar Cells with Low-Temperature UVO Photochemical Annealed Mesoporous TiO2 Layers

In recent years, the field of perovskite solar cells (PSCs) has seen rapid development, with most high-efficiency devices incorporating dense titanium dioxide (TiO₂) barrier layers and mesoporous TiO₂ layers to enhance selective electron transport. However, the manufacturing process requires high-temperature sintering steps above 450 °C, leading to significant energy consumption. In addition, this requirement greatly limits the potential applications of PSCs in the field of flexible electronics. This study introduces a new method for preparing dense-layer-free mesoporous PSCs using low-temperature UVO annealing of m-TiO₂. UVO annealing effectively removes residual organic components from m-TiO₂ precursor films, enhances the conductivity and wettability of the films, thereby reducing carrier recombination and improving the performance of PSCs. Research has shown that PSC with a 40 min UVO annealed m-TiO₂ layer exhibits a final photoelectric conversion efficiency of 17.79%, comparable to devices with traditional high-temperature annealed m-TiO₂ PSCs. In addition, after 7 days at room temperature and ambient humidity, the unpackaged device maintains a maximum conversion efficiency of 84%. These findings indicate that UVO light annealing is a feasible alternative to high-temperature annealing, providing a simpler, more cost-effective, and energy-saving method for the preparation of metal oxide electron transport layer in PSCs.