The study of optical and thermoelectric properties of lead-free variant iodes (K/Rb)2TiI6; Renewable energy

Abstract

The solar cells and thermoelectric generators are the main sources of renewable energy. In current article, we have analyzed the electronic, optical, and transport characteristics of K2TiI6 and Rb2TiI6 by density functional theory (DFT) based Wien2k code through modified Becke and Johnson (mBJ) potential. The structural and thermodynamic stability are certified by tolerance factor (0.99–1.0) and negative formation energy. The bonding nature is illustrated by color charge density. The band gap of 1.39 eV and 1.48 eV for K2TiI6 and Rb2TiI6 demonstrate the maximum absorption of light takes place in visible region (1.5 eV–3 eV), which makes them new potential materials for solar cells. Moreover, the reflection of light and optical loss is negligible in the visible region. The transport characteristics have been explained by classical Boltzman transport (CBT) based BoltzTraP code in terms of thermal to electrical conductivity ratio, Seebeck coefficient, and figure of merit. The figure of merit lies between 0.75 to 0.76, which is decent for thermoelectric characteristics.

Keywords

• Density functional theory
• Visible region band gap
• Solar cell
• Transport properties
• Polar covalent bonding