Monolayer C7 N6

Room-temperature excitons with large binding energies and high thermal conductivities

authored by

Yu Wu, Ying Chen, Congcong Ma, Zixuan Lu, Hao Zhang, Bohayra Mortazavi, Bowen Hou, Ke Xu, Haodong Mei, Timon Rabczuk, Heyuan Zhu, Zhilai Fang, Rongjun Zhang, Costas M. Soukoulis

Abstract

Two-dimensional (2D) carbon nitrides compounds have attracted wide attention in recent years due to their diverse structures and excellent electronic, thermal, and optical properties. Here, by using first-principles approach, we investigate in details the stability, many-body effect, electronic/thermal transport properties, and thermoelectric performance of monolayer C7N6, as a new kind of 2D carbon nitride compounds composed of sp2-hybridized carbon atoms forming hexagonal lattice. Our results show that C7N6 monolayer is a direct band-gap semiconductor with a band-gap value of 3.56 eV under the accurate G0W0 method. Ab initio molecular dynamics simulations demonstrate that C7N6 maintains stable up to 1500K. Two exciton absorption peaks can be observed within the band gap with the respective large binding energies of 0.84 and 0.09eV, which means both excitons can exist at room temperature. Monolayer C7N6 possesses high carrier mobility with the order of 102-103cm2V-1s-1. Moreover, we find that the lattice thermal conductivity for C7N6 is as high as 134.55W/mK at room temperature, thus the thermoelectric figure of merit for C7N6 is relatively low. Our work suggests that C7N6 is a promising candidate for nanoscale (opto-)electronic and heat transport devices.

Organisation(s)

PhoenixD: Photonics, Optics, and Engineering - Innovation Across Disciplines

External Organisation(s)

Fudan University
Nanjing University
Bauhaus-Universität Weimar
Ames Laboratory

Type

Article

Journal

Physical Review Materials

Volume

4

Publication date

06.2020

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Materials Science(all), Physics and Astronomy (miscellaneous)

Electronic version(s)

https://doi.org/10.1103/PhysRevMaterials.4.064001 (Access: Closed)