Best thermoelectric efficiency of ever-explored materials

A thermoelectric device is a heat engine that directly converts heat into electricity. Many materials with a high figure of merit ZT have been discovered in the anticipation of a high thermoelectric efficiency. However, there has been a lack of investigations on efficiency-based material evaluation, and little is known about the achievable limit of thermoelectric efficiency. Here, we report the highest thermoelectric efficiency using 12,645 published materials. The 97,841,810 thermoelectric efficiencies are calculated using 808,610 device configurations under various heat-source temperatures (Th) when the cold-side temperature is 300 K, solving one-dimensional thermoelectric integral equations with temperature-dependent thermoelectric properties. For infinite-cascade devices, a thermoelectric efficiency larger than 33% (≈⅓) is achievable when Th exceeds 1400 K. For single-stage devices, the best efficiency of 17.1% (≈1/6) is possible when Th is 860 K. Leg segmentation can overcome this limit, delivering a very high efficiency of 24% (≈1/4) when Th is 1100 K.