Enhanced thermoelectric performance of Cu2SnSe3 by synergic effects via cobalt-doping

Diamond-like Cu2SnSe3 has drawn intensive attention as an excellent environmentally-friendly p-type thermoelectric material. In this study, the effects of Co-doping at Sn site on its thermoelectric properties were investigated. Results revealed an effective increase in carrier concentration and enhancement of density-of-states (DOS) effective mass m* due to the role of Co as acceptor and probably the contribution of its d states in the valence bands. Consequently, a remarkable power factor of up to 9.55 mu W cm(-1) K-2 has been achieved at 823 K. In addition, lattice thermal conductivity was strongly suppressed due to the intensified phonon scattering and softening of bonding as revealed by the sound velocity analysis. Ultimately, a maximal ZT of 0.97 at 823 K and an average ZT of similar to 0.7 have been achieved in Cu2Sn0.88Co0.12Se3, almost double that of the pristine one.