Low-temperature processed rare-earth doped brookite TiO2 scaffold for UV stable, hysteresis-free and high-performance perovskite solar cells

Metal amine halide perovskite solar cells (PSCs), as a promising next generation photovoltaic device, have undergone an unexpected swift growth in the past decade. However, the practical application of PSCs is still facing the challenge of improving efficiency and stability, and the interfacial defects at mesoporous scaffolds is the crucial bottleneck need to be solved. Here, to heal defects and enhance performance, we implement four advantageous designs, i.e. low-temperature processing, rare-earth ion doping, brookite TiO2 scaffolds, and SnO2 blocking layer. As a result, the binder-free and sinter-free processing generates a single crystalline phase, evenly distributed, mesoporous Sc3+ doped brookite TiO2 scaffold, which induces a uniform coverage, void-less and high-quality perovskite layer. The favorable energy level alignment, diminished defects and carrier recombination improve the performance of the device. Consequently, the PSC based on Sc3+ tailored brookite TiO2 scaffold achieves a power conversion efficiency of 21.75% with hysteresis-free and excellent UV stability.