A Synergy Effect of Coadditives for Vertical Orientation of Two-Dimensional Perovskite Solar Cells Based on Butylammonium Iodide with Improved Efficiency

Two-dimensional (2D) perovskites show better resistance and optoelectronic characteristics than three-dimensional compounds. However, the high exciton energy and insufficient interfacial charge flow significantly reduce perovskite device performance. In this regard, a strategy to obtain high-performance 2D perovskite solar cells employing synergistic impact of coadditives (NH4SCN and HCl) to enable the proper alignment of perovskite films through the substrate, which eventually increases crystallinity and charge transport of 2D perovskites and reduces defect states, is presented. This coadditive method successfully generates homogeneous 2D perovskite films with consistent crystal structures and higher film quality. The champion 2D perovskite device exhibited a photovoltaic performance of 16.45% with an improved Jsc. These results suggest that developing additive engineering might result in remarkably stable and efficient 2D perovskite materials.