High‐Performance Industrial‐Grade p‐Type (Bi,Sb)₂Te₃ Thermoelectric Enabled by a Stepwise Optimization Strategy

Abstract

As the sole dominator of the commercial thermoelectric (TE) market, Bi₂ Te₃ -based alloys play an irreplaceable role in Peltier cooling and low-grade waste heat recovery. Herein, to improve the relative low TE efficiency determined by the figure of merit ZT, an effective approach is reported for improving the TE performance of p-type (Bi,Sb)₂ Te₃ by incorporating Ag₈ GeTe₆ and Se. Specifically, the diffused Ag and Ge atoms into the matrix conduce to optimized carrier concentration and enlarge the density-of-states effective mass while the Sb-rich nanoprecipitates generate coherent interfaces with little loss of carrier mobility. The subsequent Se dopants introduce multiple phonon scattering sources and significantly suppress the lattice thermal conductivity while maintaining a decent power factor. Consequently, a high peak ZT of 1.53 at 350 K and a remarkable average ZT of 1.31 (300-500 K) are attained in the Bi_0.4 Sb_1.6 Te_0.95 Se_0.05 + 0.10 wt% Ag₈ GeTe₆ sample. Most noteworthily, the size and mass of the optimal sample are enlarged to Ø40 mm-200 g and the constructed 17-couple TE module exhibits an extraordinary conversion efficiency of 6.3% at ΔT = 245 K. This work demonstrates a facile method to develop high-performance and industrial-grade (Bi,Sb)₂ Te₃ -based alloys, which paves a strong way for further practical applications.