Single-layer BiOBr: An effective p-type 2D thermoelectric material

Bismuth compounds have been playing an important role in thermoelectric (TE) applications. To match the high figure of merit (ZT) of n-type Bi-based TE materials for constructing effective TE devices, searching for p-type Bi-based TE materials with high ZT is highly desirable. Inspired by the successful exfoliation of BiOBr atomic layers [Wu et al., Angew. Chem. 130(28), 8855 (2018)], we systematically study the TE properties of single-layer BiOBr by using density functional theory and semiclassical Boltzmann transport theory, and we find that the p-type doped single-layer BiOBr exhibits a peak ZT value of 1.84 at 800 K, exceeding the highest value ever achieved among bulk p-type Bi-based TE materials (ZT = 1.4) [Poudel et al., Science 320(5876), 634 (2008)].