<p>Doping of luminescent quantum dots is needed to control their optical properties. Inserting defects may change the band gap of the photoluminescence emission as well as their emission rates both radiative and non-radiative. Several doping materials in graphene quantum dots (GQDs) have been previously studied. In this paper, we present the influence of single doping (nitrogen) and co-doping (nitrogen–sulfur) on the optical properties of GQDs. Systematic analysis of the quantum yield in correlation with lifetime measurements enables the extraction of both radiative and non-radiative transfers. By changing the ratio of carbon supply over (S,N) dopants, we can control the emission quantum yield by modifying the radiative and non-radiative transfer rates. Based on our results, we propose an optimal doping concentration for higher quantum yield that maximizes radiative transfers.</p> Graphical Abstract <p></p>