Investigation of strain behavior and carrier mobility on organic-inorganic hybrid perovskite: (C4H9NH3)2GeI4 and (C4H9NH3)2SnI4
Two dimensional (2D) organic-inorganic hybrid perovskites have attracted great interest due to tunable band gap and structural stability. In this study, biaxial strain behavior and carrier mobility for monolayer (C4H9NH3)2GeI4 and (C4H9NH3)2SnI4 are investigated by first principles calculations. (C4H9NH3)2GeI4 and (C4H9NH3)2SnI4 still keep the structural stability at ε = 13% and ε = 15%, respectively. Ab initio molecular dynamics (AIMD) simulation has verified that the system at 300 K is still thermodynamically stable at the biaxial strain of ε = 8%. The band gaps of (C4H9NH3)2GeI4 and (C4H9NH3)2SnI4 calculated from HSE06 functional are increased from 2.427 and 1.953 eV at zero strain to 3.002 and 2.626 eV at ε = 8%. The deformation potential (DP) models based on longitudinal acoustic phonon (LAP) and optical phonon (OP) scatterings are used to investigate mobility. The mobility for (C4H9NH3)2GeI4 is lower than that for (C4H9NH3)2SnI4. It is mainly determined by the scattering from OP with lower energy, and decreases sharply with the increase of biaxial strain. Compared with Pb based perovskite, (C4H9NH3)2SnI4 exhibits high carrier mobility and thermodynamic stability.