Valley-polarization and stable triplet exciton formation in 2D lateral heterostrcuture of hBN-kagome and graphene

TL;DR

This study proposes a 2D heterostructure of hBN-kagome and graphene that exhibits valley polarization and stable triplet excitons, promising for valleytronics and optoelectronics.

Contribution

It introduces a novel lateral heterostructure with opposite Berry curvature and confirms stable triplet excitons via first-principles calculations.

Findings

Opposite Berry curvature in K and K' valleys.

Insignificant intervalley coupling, enabling valley polarization.

Higher binding energy of triplet excitons (0.46 eV).

Abstract

Broken spatial inversion symmetry in semiconducting materials with time-reversal pair valleys can exhibit valley polarization. Based on first-principles calculations, here we propose a lateral heterostructure of kagome lattice of hBN and hexagonal graphene domains that exhibits opposite Berry curvature in inequivalent K and K' valleys. Explicit consideration of excitonic scattering processes within GW and Bethe-Salpeter equation formalism confirm insignificant intervalley coupling and consequent valley polarization ability along with 0.46 eV higher binding energy of triplet excitons. Such heterostructure with large charge carrier mobility can be exploited for advanced valleytronic and optoelectronic applications.