Enhanced Light Absorption by Facile Patterning of Nano-Grating on Mesoporous TiO(2) Photoelectrode for Cesium Lead Halide Perovskite Solar Cells

CsPbIBr(2), a cesium-based all-inorganic halide perovskite (CsPe), is a very promising alternative material to mainstream organic–inorganic hybrid halide perovskite (HPe) materials owing to its exceptional moisture stability, thermal stability, and light stability. However, because of the wide band gap (2.05 eV) of CsPbIBr(2), it has a low power conversion efficiency (PCE), which hinders its application in highly efficient solar cells. In this study, a facile nanoimprinted one-dimensional grating nanopattern (1D GNP) formation on mesoporous TiO(2) (mp-TiO(2)) photoelectrodes was introduced to improve the effective light utilization and enhance the performance of CsPbIBr(2) perovskite solar cells (PSCs). The 1D GNP structure on the mp-TiO(2) layer increases the light absorption efficiency by diffracting the unabsorbed light into the active mp-TiO(2) and CsPbIBr(2) layers as well as increasing the charge separation and collection due to the extended interfacial contact area between the mp-TiO(2) and CsPbIBr(2) layers. Consequently, both the current density (J(SC)) and the fill factor (FF) of the fabricated cells improved, leading to over a 20% enhancement in the solar cell’s PCE. Thus, this periodic grating structure, fabricated by simple nanoimprinting, could play an important role in the large-scale production of highly efficient and cost-effective Cs-based PSCs.