Structural and compositional properties of 2D CH 3 NH 3 PbI 3 hybrid halide perovskite: a DFT study.

Two-dimensional (2D) hybrid halide perovskites have been scrutinized as candidate materials for solar cells because of their tunable structural and compositional properties. Results based on density functional theory demonstrate its thickness-dependent stability. We have observed that the bandgap decreases from the mono- to quad-layer because of the transformation from 2D towards 3D. Due to the transformation, the carrier mobility is lowered with the corresponding smaller effective mass. On the other hand, the multilayer structures have good optical properties with an absorption coefficient of about 10 5 cm -1 . The calculated absorption spectra lie between 248 nm and 496 nm, leading to optical activity of the 2D multilayer CH 3 NH 3 PbI 3 systems in the visible and ultraviolet regions. The strength of the optical absorption increases with an increase in thickness. Overall results from this theoretical study suggest that this 2D multilayer CH 3 NH 3 PbI 3 is a good candidate for photovoltaic and optoelectronic device applications.