Effects of tensile strain on the electronic, optical and ferroelectric properties of a multifunctional R3c InFeO3 compound

Abstract

The search for materials with appropriate ferroelectric and photovoltaic properties is an intense field of research. The main objective of these studies is to obtain efficient materials for solar cell applications. In this work, non-collinear spin density functional theory calculations are performed to describe the electronic, optical, and ferroelectric properties of a multiferroic R3c InFeO3 compound under tensile strain. Our studies reveal that under conditions of tensile strain, this material had ideal fundamental properties for photovoltaic applications. Under 9% tensile strain of the R3c InFeO3 unit cell volume (a = 5.536 Å and c = 13.808 Å), a direct energy band gap of 1.74 eV was found. With this energy band gap, the material absorbs the entire range of visible light, and for a film thickness of up to 100 nm it reaches a maximum photoconversion efficiency of 20%, a higher value than observed in some semiconductors that are used in practice. Furthermore, the effective mass of charge carriers (m*), and the exciton binding energy (Eb) are significantly decreased (m* < 0.4 m0 and Eb < 1.0 meV), which likely to lead to better charge mobility and easier separation of the electron-hole pair in the process of photoabsorption. Under this level of strain, the spontaneous electric polarization was reduced to 77.6 µC/cm2, a value that is still higher than other ferroelectric-photovoltaic materials.