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

Abstract

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 TiO 2 scaffolds, and SnO 2 blocking layer. As a result, the binder-free and sinter-free processing generates a single crystalline phase, evenly distributed, mesoporous Sc 3+ doped brookite TiO 2 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 Sc 3+ tailored brookite TiO 2 scaffold achieves a power conversion efficiency of 21.75% with hysteresis-free and excellent UV stability. Low-temperature, rare-earth ion doping, brookite TiO 2 , and SnO 2 blocking are used together. Rigid device achieves an efficiency of 21.75% with hysteresis-free, and the flexible device obtains an efficiency of 11.80%. • Low-temperature, RE doping, brookite TiO 2 , and SnO 2 blocking are used together. • SnO 2 /brookite bilayer and Sc 3+ doping optimize energy level and charge extraction. • The device gives a PCE of 21.75% with negligible hysteresis and good UV stability. • Flexible device based on ITO-PEN substrate obtains a PCE of 11.80%.