Novel Li rich perovskites Li4NBI3 (B = Ge, Sn, or Pb) with high mobility based on super alkali cation Li4N

Abstract

It is an important research goal to find new environment-friendly and stable materials for sustainable and green energy applications. This paper reports a new type of super alkali perovskite Li4NBI3 (B = Ge, Sn, or Pb) with high mobility that was designed and studied by using the first-principle calculation method based on density functional theory. The geometrical structures, thermodynamic stability, electronic properties, transport properties, mechanical properties, and optical absorption properties of Li4NBI3 perovskites were calculated. The effects of the super alkali cluster Li4N on the structure and electronic properties of these perovskites were investigated. The results show that ionic bonds are formed between Li4N and I, and that the local energy state provided by Li4N increases the density of states at the edge of the energy band, which affects the energy band structure and pseudo-bandgap, and further affects the optical absorption coefficient and carrier mobility. Mechanical parameters showed that these three perovskites have high ductility, so they are suitable for making thin films. With high conductivity, strong light absorption, these perovskites are likely to become potential candidates for new energy materials.