Electronic and Optical Properties of monolayer boron nitride on a graphite substrate

In this work, we investigate the electronic and optical properties of monolayer boron nitride (mBN) grown on Highly Ordered Pyrolytic Graphite (HOPG) substrate based on density functional theory and many-body perturbation theory. Our results indicate that the screening of the semi-metallic graphite substrate results in a giant bandgap renormalization of mBN. Also, we find a huge reduction of exciton binding energy in the presence of HOPG substrate and a blue-shifting of the 1s-exciton energy to above 6 eV. Furthermore, we demonstrate that strong electron–phonon interactions also play an important role in the optical process of mBN and give rise to the multiple phonon sidebands as observed from photoluminescence measurements. As a result, we propose that both the strong dielectric screening from the substrate and the strong electron–phonon interaction must be explicitly included to the analysis of luminescence measurements.