Challenging breaking thermoelectric performance limits by twistronics

Abstract

With today's scarce resources, the issue of energy conversion is of great concern. Thermoelectric materials are capable of converting thermal energy to electrical energy. An excellent figure of merit (ZT) requires a high power factor and low thermal conductivity. Electron crystal-phonon glass materials can satisfy both these conditions. When phonon glass transforms into phonon liquid, it is of lower thermal conductivity and thus achieves a higher ZT. In this study, a twisted bilayer borophene (TBB) with a twist angle of 21.79° on a Ag(111) film is investigated. The bilayer borophene without twist angles has been synthesized experimentally [X. Liu, Q. Li, Q. Ruan, M. S. Rahn, B. I. Yakobson and M. C. Hersam, Nat. Mater., 2022, 21, 35–40]. The large cell size of 21.79° TBB creates favorable conditions for the short-range disordered phonon liquid state, which leads to a decrease in thermal conductivity and excellent ZT values.