Realize High Thermoelectric Properties in n-Type BiTeSe/YO Nanocomposites by Constructing Heterointerfaces.

Due to the excellent thermoelectric performance, bismuth telluride (BiTe) compounds are highly promising for the thermoelectric conversion in the room temperature range. However, the inferior thermoelectric performance of the n-type leg severely restricts the applications of BiTe-based thermoelectric couples. Herein, n-type BiTeSe (BTS)-based thermoelectric materials incorporated with nanosized YO (0.5-3 wt %) are prepared and their thermoelectric properties are systematically studied. The dramatically improved thermoelectric performance is ascribed to the realization of a multiscale feature of YO nanoparticle (NP)-induced interfacial decorations distributed along grain boundaries, which creates massive BTS/YO interfaces for the manipulation of carrier and phonon transport properties. The geometric phase analysis is employed to further confirm the condition of local strain in the BTS composite incorporated with YO NPs. Due to the presence of heterointerfaces and high density of dislocations in BTS matrices, the minimum lattice thermal conductivity (κ) of the nanocomposites (NCs) is dramatically suppressed from 0.76 to 0.37 W m K. With the incorporation of 3 wt % YO NPs, the Vickers hardness of the BTS/YO NC is increased by about 32%. Overall, the BTS + 1.5 wt % YO NC maintains excellent thermoelectric properties (ZT = 1.1) in the whole operative temperature range (300-500 K). The present strategy of implementing high-density heterogeneous interfaces by YO NP addition offers an applicable pathway for fabricating high-performance thermoelectric materials with both optimized thermoelectric properties and mechanical properties.