Theoretical investigation of red-shifted emission of graphitic boron doping in graphene quantum dots

Graphene quantum dots (GQDs) are promising as luminescent materials in wide fields of applications. However, the narrow emission only at visible region restricts their further development. In this work, graphitic boron doping in GQDs have been theoretically investigated which yield red-shift emission of GQDs to NIR-MIR region. Calculated results reveal that both BC2 and BC3 bonding would narrow HOMO-LUMO gaps which achieve redshift of emission from 482 nm to 5619 nm. Moreover, for multiple B atoms doped GQDs containing both BC2 and BC3, these two bonding structures exhibit opposite trends: BC2 only dominates electron distribution at HOMO energy level while BC3 only dominates LUMO. Furthermore, geometrical distortion introduced by Bdoping shows less impact on electronic and optical properties of GQD. This work reveals the mechanism of BC2 and BC3 bonding affecting electronic and optical properties and provides approaches to achieve red-shifted emission in NIR region of GQDs with considerable emission efficiency.