Dilute Sc/Y doping in SnTe for efficient charge transport modulation and high thermoelectric performance

Abstract

As a highly potential environmental-friendly medium-temperature thermoelectric material, pure SnTe exhibits relatively poor performance due to its intrinsic high carrier concentration and large energy offset between the two valence bands. In the present work, dilute Sc/Y doping is innovatively adopted to synergistically decrease carrier concentration and achieve strong band convergence. The Hall measurement results indicate that 3 % Y doping realizes the lowest carrier concentration of 2.6 × 1019 cm−3 in SnTe. Sc and Y have similar effects in promoting band convergence, with their effects second only to toxic Hg elements at the same doping concentration. The effective decoupling of electrical and thermal transport parameters results in a high average ZT of 0.453 for Sn0.975Sc0.025Te sample, which is 103 % higher than that of pure SnTe. In addition, with Li2Te alloying to regulate carrier concentration, high-performance temperature range could be adjusted, which is more conducive to dealing with different temperature scenarios. The role of Sc/Y doping disclosed in this work provides more options for further improving the performance of SnTe-based materials.