DFT investigation on the electronic and thermoelectric properties of ternary semiconductor AgBiS2 for energy conversion application

Via the FP-APW+lo method, we have performed a systematic theoretical study of the structural, electronic and thermoelectric properties of beta-AgBiS2 compound. The estimated structural properties such as cell parameters a and c, c/a ratio and internal parameters are in reasonable agreement with the earlier measured one. From band structure calculations we have found that beta-AgBiS2 is semiconductor with a band gap of 1.23 eV using the TB-mBJ approximation. In addition, the analysis of the total and partial DOS shows a considerable hybridization between Ag 'd' states and S 'p', Bi 's' states indicating that both Ag-S and Bi-S have covalent character. The main thermoelectric properties such as electrical conductivity, thermo-power, electronic thermal conductivity, power factor and figure of merit are calculated and discussed. We observed that ZT increases when temperature is augmented and reached its maximum of 0.95 and 0.85 at 2 x 10(19) cm(-3) for p and n-type doping, respectively. Thus, beta-AgBiS2 compound has interesting thermoelectric properties in both p and n-type doping.