Temperature and carrier-concentration dependences of the thermoelectric properties of bismuth selenide dioxide compounds

We performed an ab-initio electronic structure calculation for the bismuth selenide compound with oxygen substitution by using the all-electron full-potential linearized augmented plane-wave (FLAPW) method. The spin-orbit coupling in the second variational scheme and the screenedexchange local density approximation (sX-LDA) were adapted, and a large enhancement of the indirect band gap from 0.13 to 0.78 eV over the conventional LDA result was found. Exploiting the FLAPW wave-functions, we employed Boltzmann’s equation in a constant relaxation-time approach to estimate the thermoelectric (TE) transport properties, including the Seebeck coefficient, the electrical conductivity and the power factor. The temperature and the carrier-concentration dependences of the TE properties were investigated in detail to find the effect of oxygen substitution on and to search for the optimal doping and temperature range for better thermoelectric performance.