Computational 2D Materials Database: Electronic Structure of Transition-Metal Dichalcogenides and Oxides

TL;DR

This paper provides a comprehensive first-principles analysis of the electronic structures of 51 monolayer transition-metal dichalcogenides and oxides, including band structures, alignments, and exciton properties, with data available in an open database.

Contribution

It offers a systematic computational study of 2D transition-metal compounds, highlighting trends and providing an open database for future research.

Findings

QP band structures with spin-orbit coupling calculated for 51 materials

Analysis of band edge positions and heterostructure alignments

Estimation of exciton binding energies using a 2D hydrogenic model

Abstract

We present a comprehensive first-principles study of the electronic structure of 51 semiconducting monolayer transition metal dichalcogenides and -oxides in the 2H and 1T hexagonal phases. The quasiparticle (QP) band structures with spin-orbit coupling are calculated in the $G_0W_0$ approximation and comparison is made with different density functional theory (DFT) descriptions. Pitfalls related to the convergence of $GW$ calculations for 2D materials are discussed together with possible solutions. The monolayer band edge positions relative to vacuum are used to estimate the band alignment at various heterostructure interfaces. The sensitivity of the band structures to the in-plane lattice constant is analysed and rationalized in terms of the electronic structure. Finally, the $q$-dependent dielectric functions and effective electron/hole masses are obtained from the QP band structure and used as input to a 2D hydrogenic model to estimate exciton binding energies. Throughout the paper we focus on trends and correlations in the electronic structure rather than detailed analysis of specific materials. All the computed data is available in an open database.