The electronic structure, elastic properties, dynamical stability and thermoelectric properties of rock-salt and orthorhombic phases of CdS: First-principles calculations

Combined with first-principles calculation and Boltzmann transport theory, we investigated the electronic structure, dynamic stability, mechanical and thermoelectric properties of rock-salt (rs-CdS) and orthorhombic CdS (orth-CdS). Both phases are mechanical and dynamical stable, showing semiconductor characteristics with an indirect band gap of ∼0.2 eV and excellent resistance to deformation and external pressure. Due to the strong coupling of optical and acoustic phonon branches, the predicted lattice thermal conductivities of these phases are quite low. The electron transport properties including Seebeck coefficient and power factor of p-type doping are excellent. From 300 K to 800 K, the maximum ZT values are in the range of 0.56 to 0.71 for p-type doping, hinting that the rs-CdS and orth-CdS are superior thermoelectric materials.