Enhanced Light Absorption by Facile Patterning of Nano-grating on Mesoporous TiO2 Photoelectrode for Cesium Lead Halide Perovskite Solar Cells

CsPbIBr 2 , a type of cesium based all-inorganic halide perovskite (CsPe) composition, has been proposed as an alternative perovskite material against the mainstream organic–inorganic hybrid halide perovskite (HPe) materials owing to its exceptional humidity, thermal, temperature, and light stability. However, the low power conversion efficiency ( PCE ) due to its wide bandgap (2.05 eV) is an obstacle for its application in developing highly efficient solar cells. In this study, facile nanoimprinted one-dimensional grating nanopattern (1D GNP) formation on mesoporous TiO 2 (mp-TiO 2 ) photoelectrode has been introduced to improve the effective light utilization for enhancing the performance of CsPbIBr 2 perovskite solar cells (PSCs). The 1D GNP structure on mp-TiO 2 layer can not only increase the light absorption efficiency by diffracting the unabsorbed light into the mp-TiO 2 and CsPbIBr 2 active layer, but can also increase the charge separation and collection due to the enlarged interfacial contact area between the mp-TiO 2 and CsPbIBr 2 layers. Consequently, both current density ( J SC ) and fill factor ( FF ) of the fabricated cells were improved leading to over 20% improvement in their PCE . Thus, we conclude that this periodic grating structure, fabricated by simple solvent-assisted nanoimprinting, can play an important role in the realization of high-efficiency and low-cost Cs-based PSCs.