Theoretical investigation on structural, electronic, optical and elastic properties of TiO2, SnO2, ZrO2 and HfO2 using SCAN meta-GGA functional: A DFT study

Abstract

Performance optimization of different layers of a perovskite solar cell is really important to augment its efficiency. Taking this into consideration, potential semiconductor materials for the electron transport layer have been studied using density functional theory. In this work, first-principle calculation of room temperature phase TiO2, SnO2, ZrO2 and HfO2 have been performed using meta-generalized gradient approximation functional (meta-GGA) with strongly constrained and appropriately normed (SCAN), the semi-local exschange-correlation function. For structural properties, we have optimized the unit cell structures of all the oxides and obtained the lattice parameters. In the electronic properties, the band structures and density of states are calculated and analyzed in detail. Also, real and imaginary parts of dielectric function, absorption coefficient, extinction coefficient, reflectivity and refractive index are calculated for in-depth analysis of the important optical properties. TiO2 and SnO2 have shown good characteristics that are required for photovoltaic applications. Further, the loss spectrum and optical conductivity have been estimated. Moreover, the elastic properties are also evaluated for examining the mechanical stability and hence the related elastic parameters such as bulk and shear moduli, Young's modulus, Pugh and Poisson's ratios and hardness parameters.