A record high average ZT over a wide temperature range in a Single-layer Sb2Si2Te6

Conversion of waste heat into usable energy requires development of thermoelectric materials with high efficiency in a wide temperature range. Using first principles theory and Boltzmann transport theory, we show that the thermoelectric performance of the p-type single-layer Sb2Si2Te6 has a high figure of merit ZT of 2.62 at 900 K and a record high average ZT of ~1.93 (corresponding the conversion efficiency of ~23.2%) in the temperature range of 300‐900 K. These values are significantly higher than the recently measured average ZT of ~0.57 in the temperature range of 310–823 K [Luo et al., Joule 4, 159–175 (2020)] in layered bulk Sb2Si2Te6. We attribute the large enhancement of ZT in the single layer material to the increase in the thermoelectric power factor resulting from the complex Fermi surface. Our work reveals the great potential of a single-layer Sb2Si2Te6 for wide-temperature-range thermoelectric applications.