Identifying Resonant Dopants for BaCu2S2 from First Principle Calculations for Thermoelectric Applications

Abstract

Distortion of the density of states(DOS) via resonant level has been reported to improve the thermoelectric figure of merit (ZT) of material. BaCu2S2 exists in two phases a high-temperature tetragonal phase and a low-temperature orthorhombic phase. In this study, we tried doping various elements(Al, Ga, In, Tl, As, and Sb) at different sites of both phases. For the lowest formation energy configurations, we further explored the effect of various dopants in the electronic structure of the compound. Some of the dopants created new defect states overlapping with the parent states(resonant level), close to the band edge. Tl created defect states in both the VB and CB band edges. Studied the thermoelectric properties of dopants. Group 13 dopants in the orthorhombic phase showed a carrier concentration-dependent improvement in Seebeck coefficients for both the holes and electrons due to the resonant level.