First-principles calculations on structural, electronic, elastic, optical and thermoelectric properties of thallium based chloroperovskites TlMCl3 (M = Zn and Cd)

In this work, we have studied the structural, electronic, elastic, optical and thermoelectric properties of Tl-based chloroperovskite materials TlMCl3 (M = Zn and Cd) in the cubic structure using density functional theory (DFT) which executed in 'Quantum ESPRESSO' code. The structural optimization is performed by the Birch-Murnaghan equation of state and the optimized lattice parameters are 4.98 angstrom for TlZnCl3 and 5.225 angstrom for TlCdCl3. The electronic properties show that the compounds are semiconductors with an indirect band gap of 1.5 eV and 1.84 eV for TlZnCl3 and TlCdCl3, respectively. The elastic properties reveal that the materials are mechanically stable, ductile, and anisotropic. The optical properties of compounds have been studied in range [0-20]eV, they have a high absorption coefficient close to 10(5)cm(-1) in the ultraviolet range. The thermoelectric properties are evaluated as a function of chemical potential for different temperatures, and the figure of merit obtained is 0.99 for compounds at room temperature. The results show that the compounds are important materials and can be used as scintillators, as well as for thermoelectric applications.