Effect of Cs on the Stability and Photovoltaic Performance of 2D/3D Perovskite-Based Solar Cells

One of the attractive features of hybrid perovskite is the possibility to reduce its dimensionality, which enhances the perovskite's resistivity to moisture. In this work, we used 2D/3D perovskites to study different organic molecular spacers (aromatic ring vs cyclic ring); Cs was introduced as an additional small cation to methylammonium. It was found that Cs improves the photovoltaic performance; however, it reduces the cells' stability because two cations having a different ionic radius are mixed, which creates strains in the perovskite structure. The aromatic ring spacers display better stability in complete cells than does the cyclo spacer. Importantly, Cs has a greater effect on the stability than does the nature of the spacer molecule. The difference in the size of the organic cations as well as the inorganic cations plays a major role in the perovskite's stability in a film and in a complete solar cell.