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arXiv · 1905.12992

Designing graphene/hexagonal boron nitride superlattice monolayer with high thermoelectric performance

Zizhen Zhou·Huijun Liu·Dengdong Fan·Guohua Cao
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Abstract

We design a hybrid graphene/hexagonal boron nitride superlattice monolayer and investigate its thermoelectric properties using density functional theory and Boltzmann transport equations with the relaxation time accurately treated by electron-phonon coupling calculations. Compared with that of pristine graphene, the lattice thermal conductivity of the superlattice structure is more than two orders of magnitude lower due to the enhanced three-phonon scattering process originated from the mixed-bond characteristics. Besides, the coexistence of light and heavy bands around the Fermi level leads to an ultrahigh power factor along the zigzag direction, where the highest ZT value of ~2.5 can be achieved for the n-type system at 1100 K. Moreover, it is noted that the carrier transport near the valance band minimum is almost entirely contributed by the graphene part of the superlattice. As a consequence, the thermoelectric performance of p-type system can be enhanced to be comparable with that of n-type one by appropriate substitution of nitrogen atom with phosphorus, which can suppress the lattice thermal conductivity but nearly have no influence on the hole transport.

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Zizhen Zhou, Huijun Liu, Dengdong Fan, Guohua Cao. 2019-05-30. Designing graphene/hexagonal boron nitride superlattice monolayer with high thermoelectric performance. https://arxiv.org/abs/1905.12992

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