Realizing high thermoelectric performance in eco-friendly SnTe via synergistic resonance levels, band convergence and endotaxial nanostructuring with Cu2Te

Abstract

Abstract SnTe is emerging as environment-friendly alternative to conventional thermoelectric material PbTe which contains toxic element. Here, we achieved an ultrahigh power factor and high thermoelectric performance of SnTe via the synergy of resonance levels, band convergence and endotaxial nanostructuring. We found that the coexistence of resonant levels (by In dopant) and band convergence (by Ca dopant) produce remarkable enhancement of Seebeck coefficient and ultrahigh power factor. The largest power factor reaches as high as ~42.2 μWcm−1K−2. Endotaxial Cu2Te nanostructures were further introduced by a phase separation strategy, which plays a dominant role in reducing the lattice thermal conductivity. Meanwhile, it is revealed that Ca and In codoping enlarges band gap, therefore suppressing bipolar thermal conductivity. These electronic and thermal effects contribute to a record high ZT of ~1.85 at 823 K and a high average ZT of 0.67. This high performance material is low-cost, earth-abundant and environmentally-friendly, which are essential for the widespread use of thermoelectric modules.