InP3 facilitating high thermoelectric performance in Te-based composites via high pressure

Abstract

Thermoelectric devices as eco-friendly candidates for energy conversion have attracted increasing interest as a sustainable and emission free solution to solve the environmental problem. Tellurium, is expected to be a suitable candidate, nevertheless, due to the poor electrical property, it has severely hampered the further development in practical application. This work proposes a new fabrication route for bulk Te via high pressure and high temperature method to enhance its power factor by compositing a certain quality of InP3. As InP3 decomposed into indium and black phosphorus under high pressure conditions, both the carrier concentration and Seebeck coefficient was enhanced significantly, leading to a maximum power factor of 11.4 μWcm-1K-2 at 460 K, which increase by 44.2 % compared to the peak value of pristine Te. Moreover, the induced defects, such as point defects, abundant grain boundaries and heterojunctions, strongly influence the thermoelectric performance, with a substantial decrease in lattice thermal conductivity. Consequently, the ZT values are sharply enhanced by InP3 compositing with the highest value reaching ∼0.76 of Te + 0.25 wt% InP3 at 490 K. Importantly, the average ZT value within the 300 K - 600 K range reaches to 0.48, which is 3.5 times that of the pristine Te. This work mark a step toward developing high performance thermoelectric devices for energy conversion, making elemental Te more competitive with high-performance in medium temperature range.