Organic cation rotation in HC(NH2)2PbI3 perovskite solar cells: DFT & DOE approach

In the past few years, hybrid organic–inorganic perovskites have become one of the most interesting and efficient materials for photovoltaics and optoelectronics applications. Here, we report the key role of organic cation rotation in the formamidinium lead iodide HC(NH2)2PbI3 perovskites (FAPbI3) in different rotational modes and angles. Using density functional theory (DFT) calculations, we show the significant effect of rotation on overall electronic and optical properties of FAPbI3 such as band structure, DOS, PDOS, electron density, and optical absorption spectra. Moreover, design of experiment (DOE) methodology was applied to generate a program to simultaneously optimize five distinct factors of solar cell with minimum number of calculations and high accuracy. This approach yields a detailed and remarkable insight from the interactions of mutual effective factors and how they affect the final Voc, Jsc, FF, and PCE% of the FAPbI3 solar cell. Solar cells based on this architecture exhibit power-conversion efficiency more than 20% when measured under the illumination of AM1.5G, which makes it some of the high-performing perovskite-based solar cells.