High performance Te-free thermoelectric materials and modules for Low-T applications

Thermoelectric (TE) technology converts heat into electricity directly and is a promising source of clean electricity. Commercial TE modules have relied on Bi₂Te₃-based compounds because of their unparalleled TE properties at temperatures associated with low-grade heat (<550 K). However, the scarcity of elemental Te greatly limits the applicability of such modules. Here we report the performance of TE modules assembled from Te-free compounds, including p-type MgAgSb and n-type Mg₃(Sb,Bi)₂, by using a simple, versatile, and thus scalable processing routine. We demonstrate module-level conversion efficiencies of 3% and 8.5% under temperature differences of 75 K and 260 K, respectively, and concomitantly a maximum cooling of 72 K when used as a cooler. These proof-of-principle demonstrations will pave the way for robust, high-performance, and sustainable solid-state power generation and cooling to substitute the highly scarce and toxic Bi₂Te₃.​