Nitrogen-Doping of Graphene Quantum Dots via Pulsed Laser Ablation and It’s Photoluminescence
Svette Reina Merden Santiago1*, Tzu-Neng Lin1, Ji-Lin Shen1
1Physics, Chung Yuan Christian University, Jhong-Li, Taoyuan, Taiwan
* Presenter:Svette Reina Merden Santiago,
Optical properties of graphene quantum dots (GQDs) are greatly influenced by their quantum confinement, defects, edge structures, and functionalization. Further studies have concentrated on modulating the optical properties of GQDs via heteroatom doping. Nitrogen (N) atoms have been the most utilized material for such modulation due to having comparable atomic size to carbon atoms in GQDs. In this research, we present an effective incorporation of N atoms into GQDs using pulsed laser ablation (PLA) of graphene oxide (GO) with diethylenetriamine (DETA) and urea. The morphology, chemical component and photoluminescence (PL) of synthesized N-doped GQDs (N-GQDs) have been investigated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and steady-state PL spectroscopy. The PL intensity in N-GQDs increases with respect to increasing N concentration. The origin of the PL intensity enhancement in the N-GQDs is attributed to the increased densities of pyridinic and graphitic N after N doping. Comparison of the dependence of the PL intensities in GQDs and N-GQDs on the temperature was also investigated. An anomalous temperature dependence of PL intensity was observed for N-GQDs, which was attributed to a carrier transfer mechanism from a dopant-induced state to the quantum-dot emitting state. This study is rendered advantageous in understanding the effect of N-doping on the luminescence properties of GQDs.

Keywords: Graphene Quantum Dots, Nitrogen-Doping, Temperature-dependent Photoluminescence, Pulsed Laser Ablation