Optoelectronic Properties of Graphene Quantum Dots

Graphene quantum dots (GQDs) are nanoscale fragments of graphene exhibiting pronounced quantum confinement and edge effects that endow them with tunable optoelectronic characteristics. Unlike extended graphene, GQDs possess a finite energy gap whose magnitude is dictated by size, shape and edge termination. These features give rise to size-dependent absorption and emission across the ultraviolet, visible and near-infrared regions. Surface functionalisation and heteroatom doping further modulate electronic states, enabling precise control of photoluminescence wavelengths and quantum yields. Charge-carrier dynamics in GQDs are governed by electron–hole interactions, leading to discrete excitonic transitions and the possibility of nonlinear processes such as two-photon absorption. Their exceptional photostability, biocompatibility and facile chemical modification underpin applications in bioimaging, light-emitting devices, photovoltaics and sensing. Recent advances have focused on elucidating fundamental mechanisms of photoinduced charge transfer, exploiting multiphoton excitation and engineering interfacial charge separation for efficient optoelectronic performance.

Research from Nature Portfolio

Theoretical investigations have revealed that functionalisation of GQDs with donor or acceptor groups breaks symmetry and promotes delocalisation of electron–hole pairs, producing a red shift in absorption and enhanced fluorescence. These studies clarify how photoinduced charge transfer and electron–hole coherence underpin bright, tunable emission in visible regions. In parallel, computational analyses of two-photon absorption have demonstrated that circular GQDs with well-defined armchair and zigzag edges exhibit resonant enhancement of nonlinear cross sections in the infrared. This work highlights the role of quantum confinement and edge geometry in governing multiphoton processes and suggests GQDs as promising materials for infrared photonics and deep-tissue imaging.

Optoelectronic Properties of Graphene Quantum Dots publication trend

The graph below shows the total number of articles in optoelectronic properties of graphene quantum dots across all publications each year (not limited to Nature Index journals).

Technical terms

Graphene quantum dot: A nanoscale fragment of graphene exhibiting quantum-confined electronic states and discrete energy levels.

Energy gap: The energy difference between the highest occupied and lowest unoccupied electronic states, determining optical absorption edge.

Photoluminescence: Emission of light resulting from radiative recombination of photoexcited electron–hole pairs.

Quantum yield: The ratio of photons emitted to photons absorbed, measuring fluorescence efficiency.

Two-photon absorption: A nonlinear optical process where simultaneous absorption of two photons raises an electron to an excited state.

Heteroatom doping: Introduction of foreign atoms into the carbon lattice to tailor electronic and optical properties.

References

1. Influence of B, Si, Ge, and As impurities on the electronic properties of graphene quantum dot: A density functional theory study. Nano Trends (2024).
2. Theoretical Investigations of Optical Origins of Fluorescent Graphene Quantum Dots. Scientific Reports (2016).
3. One-step synthesis of sulfur-incorporated graphene quantum dots using pulsed laser ablation for enhancing optical properties.. Optics Express (2020).
4. Synthesis of Nitrogen-Doped Graphene Quantum Dots from Sucrose Carbonization. Applied Sciences (2022).
5. Giant Two-photon Absorption in Circular Graphene Quantum Dots in Infrared Region. Scientific Reports (2016).