Effects of elemental doping on the photoluminescence properties of graphene quantum dots

Abstract

Heteroatom doping can endow graphene quantum dots (GQDs) with enhanced photoluminescence (PL) properties. With the aim of understanding the PL mechanism of GQDs and improving their PL properties, a simple strategy was used for the synthesis of GQDs and four kinds of element-doped GQDs (N/S/P/B). Compared to GQDs, nitrogen and sulfur-doping result in a blue-shifted PL emission, but phosphorus and boron doping lead to a red-shifted emission. Experimental results indicate that element doping can change structural defects, surface functional groups (especially carboxyl groups), and interactions among carbon atoms with their neighboring atoms of carbon, oxygen, and doped atoms. All the changes above can tailor the PL properties of GQDs for various applications, such as biomedical sensing and imaging.