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 (TiO 2 ) barrier layers and mesoporous TiO 2 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‐TiO 2 . UVO annealing effectively removes residual organic components from m‐TiO 2 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‐TiO 2 layer exhibits a final photoelectric conversion efficiency of 17.79%, comparable to devices with traditional high‐temperature annealed m‐TiO 2 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.