Mechanical properties of hybrid organic-inorganic CH3NH 3BX3 (B = Sn, Pb; X = Br, I) perovskites for solar cell absorbers

Abstract

The crystal structures, elastic and anisotropic properties of CH 3NH3BX3 (B = Sn, Pb; X = Br, I) compounds as solar cell absorber layers are investigated by the firstprinciples calculations. The type and strength of chemical bond B-X are found to determine the elastic properties. B-X bonds and the organic cations are therefore crucial to the functionalities of such absorbers. The bulk, shear, Young's modulus ranges from 12 to 30 GPa, 3 to 12 GPa, and 15 to 37 GPa, respectively. Moreover, the interaction among organic and inorganic ions would have negligible effect for elastic properties. The B/G and Poisson's ratio show it would have a good ductile ability for extensive deformation as a flexible/stretchable layer on the polymer substrate. The main reason is attributed to the lowshear modulus of such perovskites. The anisotropic indices AU, AB A G, A1, A2, and A3 show ABX 3 perovskite have very strong anisotropy derived from the elastic constants, chemical bonds, and symmetry. © 2014 Author(s).