  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.
