Weak donor-like effect to enhance the thermoelectric performance of Bi2Te2.79Se0.21 near room temperature

Bismuth telluride-based materials are the most celebrated thermoelectric (TE) materials near room temperature. However, for the n-type bismuth telluride-based materials, the traditional powder metallurgy (PM) method, such as grinding and ball milling, can induce strong donor-like effect. The strong donor-like effect boosts the carrier concentration n and the carrier thermal conductivity kappa(e), leading to the deterioration of both electrical and thermal performance. Herein, the basal deformation (BD) has been performed in the n-type Bi2Te3-based materials to introduce weak donor-like effect. The BD crystalline bulks were obtained through sintering the stacked crystals, which had been heavily deformed on the (00l) plane. The BD process optimizes the carrier concentration n and improves the power factor (PF). Meanwhile, the lattice thermal conductivity kappa(L) is suppressed due to the enhanced grain boundary scattering. Consequently, a peak ZT of 1.0 at 380 K has been achieved in Bi2Te2.79Se0.21, which is 24% and 30% higher than that of the original zone-melting (ZM) ingot and the polycrystalline sample by PM. This study sheds light on the further TE performance enhancement of bismuth telluride-based materials via introducing the weak donor-like effect.