Investigation of Fe2+-incorporating organic-inorganic hybrid perovskites from first principles and experiments

The development of high efficiency perovskite solar cells (PSCs) has been proved to depend on the stability and optical properties of perovskite materials. A lot of efforts have been applied to improving these properties. Among them, the alternative mixed-metal perovskite composition has been considered as a new solution for photovoltaic device applications to satisfy the demand for exploring efficient photovoltaic performance. Here, we have systematically performed first-principles calculations using density-functional theory (DFT) to study the structural, electronic, magnetic and optical properties of the perovskite CH3NH3(Pb:Fe)I-3, and investigated the effect of iron (Fe) metal ion doping on the properties of the perovskites and solar cell performance. The calculated results reveal that the perovskite CH3NH3(Pb:Fe)I-3 exhibits half-metallic behavior due to the impurity bands induced by the Fe dopant crossing the Fermi level. Consequently, it is found that the absorption intensities of CH3NH3(Pb:Fe)I-3 are slightly higher than those of CH3NH3PbI3 in the near-infrared light region. It is unexpected that the perovskite CH3NH3(Pb:Fe)I-3 exhibits a large magnetic moment of 4 mu(B) and its magnetic coupling belongs to the antiferromagnetic (AFM) configuration. Meanwhile, we found that the Fe incorporation can distort the structure due to its small ionic size, which significantly changes the device performance. Our findings provide a reference for exploring the properties of perovskite materials.