Systematic study of optoelectronic and transport properties of cesium lead halide (Cs2PbX6; X=Cl, Br, I) double perovskites for solar cell applications

• Published in: Ceramics international 2020-09, Vol.46 (13), p.21378-21387
• Main Authors: Hussain, Mujtaba, Rashid, Muhammad, Ali, Awais, Bhopal, Muhammad Fahad, Bhatti, A.S.
• Format: Article
• Language: English
• Subjects: Double perovskites; Optical properties; Solar cells; Thermodynamic stability
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2020.05.235

A systematic density functional theory investigation of Cs2PbX6 (X = Cl, Br, I) double perovskites is presented. The lattice constants are computed after structure optimization and using Birch-Murnaghan equations, which agree to the experimental literature. The mechanical stability conditions satisfy Born criteria, and the ductile nature is evidenced by the calculated Poisson's (v) and Pugh's ratios (B0/G) because all three double perovskites exhibit values higher than the respective critical values v = 0.26 and B0/G = 1.75. A detailed study of the optoelectronic properties reveals these double perovskites as promising candidates for future optical devices due to their direct band gaps (within 0.45–2.54 eV) and large absorption coefficients 5.95 × 105 cm−1, which are suitable for solar cell applications. ZT calculations demonstrate minute variations within 200–800 K and computed parameter values are quite favorable for thermoelectric applications of these materials in the future. A p-type semiconducting nature is predicted by the computed thermoelectric properties. Additionally, computed refractive indices show Cs2PbBr6 and Cs2PbI6 exhibiting super-luminescent properties in the UV range. Therefore, the studied double perovskites provide further interest for future energy conversion and photonic based technologies.