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.
Bibliographical noteFunding Information:
We would to thank the Israel Ministry of Energy for their financial support and the Israel Science foundation under the Israel−China grant.
© 2018 American Chemical Society.