Low-Temperature Processable Charge Transporting Materials for the Flexible Perovskite Solar Cells

Abstract: Organic–inorganic hybrid lead halide perovskites have been extensively investigated for various optoelectronic applications. Particularly, owing to their ability to form highly crystalline and homogeneous films utilizing low-temperature solution processes (< 150 °C), perovskites have become promising photoactive materials for realizing high-performance flexible solar cells. However, the current use of mesoporous TiO₂ scaffolds, which require high-temperature sintering processes (> 400 °C), has limited the fabrication of perovskite solar cells on flexible substrates. Therefore, the development of a low-temperature processable charge-transporting layer has emerged as an urgent task for achieving flexible perovskite solar cells. This review summarizes the recent progress in low-temperature processable electron- and hole-transporting layer materials, which contribute to improved device performance in flexible perovskite solar cells. Graphical Abstract: [Figure not available: see fulltext.].