Photovoltaic Effect of 2D Homologous Perovskites

- The mixed perovskite was prepared by exposure of MAI gas on the BAPbI4 film.
- The increased dimensional perovskite shows a smaller band gap than 2D perovskite.
- The mixed perovskite system shows the vertical crystal orientation.
- The mixed perovskite cell exhibits the higher Jsc and FF than 2D perovskite cell.

The controlled growth of mixed dimensional perovskite structures, (C6H5CH2NH2)(CH3NH3)n-1PbnI3n+1, through the introduction of CH3NH3I molecule vapor into the two-dimensional perovskite C6H5CH2NH3PbI4 structure and its application in photovoltaic devices is reported. The dimensionality of (C6H5CH2NH2)(CH3NH3)n-1PbnI3n+1 is controlled using the exposure time to the CH3NH3I vapor on the C6H5CH2NH3PbI4 perovskite film. As the stacking of the lead iodide lattice increases, the crystallographic planes of the inorganic perovskite compound exhibit vertical growth in order to facilitate efficient charge transport. Furthermore, the devices have a smaller band gap, which offers broader absorption and the potential to increase the photocurrent density in the solar cell. As a result, the photovoltaic device based on the (C6H5CH2NH2)(CH3NH3)n-1PbnI3n+1 perovskite exhibits a power conversion efficiency of 5.43% with a short circuit current density of 14.49 mA cm−2, an open circuit voltage of 0.85 V, and a fill factor of 44.30 for the best power conversion efficiency under AM 1.5G solar irradiation (100 mW cm−2), which is significantly higher than the 0.34% of the pure two-dimensional BAPbI4 perovskite-based solar cell.