Graphene Quantum Dots: Introduction and Market News
What are quantum dots?
Quantum dots, or QDs, are semiconductor nanoparticles or nanocrystals, usually in the range of 2-10 nanometers (10-50 atoms) in size. Their small size and high surface-to-volume ratio affects their optical and electronic properties and makes them different from larger particles made of the same materials. Quantum dots confine the motion of conduction band electrons, valence band holes, or excitons (bound pairs of conduction band electrons and valence band holes) in all three spatial directions. Quantum dots are also sometimes referred to as ‘artificial atoms’, a term that emphasizes that they are a single object with bound, discrete electronic states, similarly to naturally occurring atoms or molecules.
Many types of quantum dot are fluorescent - they emit light of specific frequencies if electricity or light is applied to them. These frequencies can be tuned by changing the dots' size, shape and material, opening the door to diverse applications. Generally speaking, smaller dots appear blue while larger ones tend to be more red. Specific colors also vary depending on the exact composition of the QD.
Applications
Thanks to their highly tunable properties, QDs are attracting interest from various application developers and researchers. Among these potential applications are displays, transistors, solar cells, diode lasers, quantum computing, and medical imaging. Additionally, their small size enables QDs to be suspended in solution, which leads to possible uses in inkjet printing and spin-coating. These processing techniques may result in less-expensive and less time consuming methods of semiconductor fabrication.
Quantum dots are considered especially suitable for optical applications, thanks to their ability to emit diverse colors, coupled with their high efficiencies, longer lifetimes and high extinction coefficient. Their small size also means that electrons do not have to travel as far as with larger particles, thus electronic devices can operate faster. Examples of applications that take advantage of these electronic properties include transistors, solar cells, quantum computing, and more. QDs can greatly improve LED screens, offering them higher peak brightness, better colour accuracy, higher color saturation and more.
QDs are also very interesting for use in biomedical applications, since their small size allows them to travel in the body, thus making them suitable for applications like medical imaging, biosensors, etc.
What is graphene?
Graphene is a material made of carbon atoms that are bonded together in a repeating pattern of hexagons. Graphene is so thin that it is considered two dimensional. Graphene's flat honeycomb pattern gives it many extraordinary characteristics, such as being the strongest material in the world, as well as one of the lightest, most conductive and transparent. Graphene has endless potential applications, in almost every industry (like electronics, medicine, aviation and much more).
The single layers of carbon atoms provide the basis for many other materials. Graphite, like the substance found in pencil lead, is formed by stacked graphene. Carbon nanotubes are made of rolled graphene and are used in many emerging applications from sports gear to biomedicine.
Graphene quantum dots
The term graphene quantum dots (GQDs) is usually used to describe miniscule fragments, limited in size, or domains, of single-layer to tens of layers of graphene. GQDs often possess properties like low toxicity, stable photoluminescence, chemical stability and pronounced quantum confinement effect, which make them attractive for biological, opto-electronics, energy and environmental applications.
The synthesis of graphene quantum structures, such as graphene quantum dots, has become a popular topic in recent years. While graphene usually does not have a bandgap - which is a problem for many applications - graphene quantum dots do contain a bandgap due to quantum confinement and edge effects, and that bandgap modifies graphene's carrier behaviors and can lead to versatile applications in optoelectronics. GQDs were also found to have four quantum states at a given energy level, unlike semiconductor quantum dots, which have only two. These additional quantum states, according to researchers, could make GQDs beneficial for quantum computing.
Additional properties of GQDs such as high transparency and high surface area have been proposed for energy and display applications. Because of the large surface area, electrodes using GQDs are applied for capacitors and batteries.
Various techniques have been developed to produce GQDs. Top-down methods include solution chemical, microwave, and ultrasonic methods. Bottom-up methods include hydrothermal and electrochemical methods.
Further reading
- Introduction to graphene
- Graphene Oxide
- Graphene Inks
- The Graphene Handbook, our very own guide to the graphene market
Graphene quantum dot-gold nanocomposite for drug-free antibacterial wound treatment
Researchers at China's Gannan Medical University and Shanghai University recently developed a Schottky junction-based nanocomposite that combines gold nanoparticles (AuNPs) with graphene oxide quantum dots (GOQDs), demonstrating a highly effective, antibiotic-free strategy for treating bacterial infections and accelerating wound healing.
The work addresses a known clinical challenge: the rapid rise of multidrug-resistant (MDR) bacteria driven by widespread antibiotic use. Conventional approaches - such as increasing antibiotic dosage or developing new drugs - are often limited by toxicity, long development timelines, and persistent resistance. As a result, non-invasive phototherapies, particularly photodynamic therapy (PDT) and photothermal therapy (PTT), are gaining attention as alternatives. However, each modality has intrinsic limitations: PDT efficiency is constrained by electron–hole recombination and oxygen availability, while PTT requires precise thermal control to avoid damaging healthy tissue. To overcome these constraints, the researchers engineered a hybrid nanostructure in which AuNPs and GOQDs form a Schottky junction - a metal–semiconductor interface that enables directional charge transfer.
Graphene quantum dots target Parkinson’s‑related protein aggregates
Researchers from Poznan University of Medical Sciences, Polish Academy of Sciences, Hirosaki University Graduate School of Medicine, University of Amsterdam, Florida Polytechnic University and Jagiellonian University have shown that graphene quantum dots (GQDs) can disrupt the harmful aggregation of the protein α‑synuclein (ASN), which plays a central role in Parkinson’s disease and multiple system atrophy (MSA). In these disorders, ASN assembles into stable protein clusters inside brain cells, damaging them over time; the study demonstrates that properly engineered GQDs can interfere with this clustering process and help reduce the toxic protein load.
The team synthesized custom GQDs and carried out a detailed physicochemical characterization, including their surface chemistry, charge, optical behavior and crystalline structure. This allowed them to link specific material features to biological activity, an important step for rational design of nanomaterials that interact with proteins in a controlled way. They then evaluated the GQDs in a multi‑stage experimental pipeline that covered cell‑free aggregation assays, human dermal fibroblasts, primary murine dopaminergic neurons and an in vivo MSA mouse model.
Graphene oxide quantum dots enable biosensing of depression biomarkers
University of Delhi researchers have developed an environmentally friendly method to synthesize graphene oxide quantum dots (GO QDs) for use in ultrasensitive biosensors capable of detecting key neurological biomarkers such as dopamine and serotonin. The team’s novel approach employs citric acid as a green, biodegradable precursor, successfully producing uniform, negatively charged GO QDs with an average diameter of 23.4 nm.
The synthesized GO QDs were thoroughly characterized using UV-Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), high-resolution X-ray diffraction (HR-XRD), and dynamic light scattering (DLS). The data confirmed the formation of pure, spherical QDs with well-defined structural integrity and optical stability, indicating precise control over quantum confinement and surface functionality.
Graphene quantum dot-integrated nanocomposites could help fight brain tumors
Scientists from India have studied the use of graphene quantum dot-integrated nanocomposites as a novel therapeutic strategy against glioblastoma, an aggressive and treatment-resistant type of brain tumor.
This innovative approach leverages the unique physicochemical properties of graphene quantum dots (GQDs) to enhance delivery, targeting, and efficacy of anti-cancer agents within the brain’s complex environment.
Researchers demonstrate integration of QD-functionalized GFETs with CVD graphene on a 200 mm CMOS wafer platform
Researchers at AMO, Graphenea Semiconductor and Emberion recently demonstrated a 200 mm processing platform for the large-scale production of graphene field-effect transistor-quantum dot (GFET-QD) hybrid photodetectors. Such sensors have many potential applications, ranging from surveillance, search and rescue, and vehicle safety to improved sorting of food and food packaging to reduce their environmental impact.
Schematic of the device architecture of the tandem GFET‒QD photodetector. Image from: Scientific Reports
The team addressed several of the graphene wafer-scale integration challenges, including monolayer graphene chemical vapor deposition (CVD), transfer, and patterning, which fulfill the requirements for imaging functionalization and large area deposition of the multilayer QD absorber material in an inert atmosphere, as well as methods for encapsulating devices using thin film alumina (Al2O3) and hermetically sealed semiconductor packages. Such a demonstration elevates the initial concept to higher technology readiness levels in multiple dimensions, ranging from wafer-scale graphene device statistics to the development of custom CMOS circuits and the implementation of production-ready packaging.
Researchers demonstrate orbital hybridization in graphene-based quantum dots
Researchers from Peking University and Beijing Normal University have reported orbital hybridization in graphene-based quantum dots, revealing how anisotropic confinement influences electronic states at the atomic scale. This represents a significant milestone in quantum physics and materials science, bridging the conceptual and experimental gap between artificial systems and the behaviors of real atoms.
Quantum dots, often described as artificial atoms, have been known to mimic certain characteristics of atomic orbitals. These nanostructures can recreate discrete energy levels and have successfully demonstrated artificial bonding and antibonding states. However, until now, they had not been used to simulate orbital hybridization—a fundamental process in real atoms where orbitals of different shapes and symmetries mix to form new, hybrid orbitals. This omission has limited the ability of artificial atoms to fully emulate the complexities of atomic structure. Moreover, a basic understanding of how anisotropic confinement—the directional variation in the spatial boundaries of a quantum dot—affects the potential for hybridization had been lacking.
Researchers design graphene quantum dots for cancer treatment
Researchers at China's Hunan University, Chinese Academy of Sciences and the University of Washington in the U.S have developed a metal-free nanozyme based on graphene quantum dots (GQDs) for highly efficient tumor chemodynamic therapy (CDT).
GQDs have potential as a cost-effective means of addressing the toxicity concerns associated with metal-based nanozymes in tumor CDT. However, the limited catalytic activity of GQDs has posed significant challenges for their clinical application, particularly under challenging catalytic conditions. "The obtained GQDs, which are made from red blood cell membranes, are highly effective in treating tumors with few side effects," said Liu Hongji, a member of the research team. "One of the advantages is that they are metal-free. In addition, they function as excellent peroxidase-like biocatalysts."
Researchers design semitransparent image sensors for eye-tracking applications using graphene and QDs
A team of researchers from The Barcelona Institute of Science and Technology (ICFO) and Barcelona-based startup Qurv Technologies have designed flexible, nearly transparent graphene-enhanced image sensors that could be hidden in plain sight.
The sensors, based on graphene and quantum dots, could be integrated directly onto eyeglasses or curved windshields, placed right in front of a user’s eyes. This could make eye-tracking hardware less bulky, improve the accuracy of gaze detection, and reduce computational complexity, says Frank Koppens, who co-led the research and co-founded Qurv in 2020.
Researchers create symmetric graphene quantum dots for future qubits
Researchers from Germany's RWTH Aachen University, Forschungszentrum Jülich and Japan's National Institute for Materials Science (NIMS) have found that bilayer graphene allows the realization of electron–hole double quantum dots that exhibit near-perfect particle–hole symmetry. Moreover, They showed that particle–hole symmetric spin and valley textures lead to a protected single-particle spin-valley blockade that will allow robust spin-to-charge and valley-to-charge conversion, which are essential for the operation of spin and valley qubits.
Quantum dots in semiconductors such as silicon or gallium arsenide are considered great candidates for hosting quantum bits in future quantum processors. The recent study essentially shows that bilayer graphene has even more to offer than other materials. The double quantum dots the researchers have created are characterized by a nearly perfect electron-hole-symmetry that allows a robust read-out mechanism – one of the necessary criteria for quantum computing.
Graphene quantum dots could improve magnetic field sensors
Researchers from the University of California Santa Cruz, University of Manchester and Japan's International Center for Materials Nanoarchitectonics and National Institute for Materials Science have used a scanning tunnelling microscope to create and probe single and coupled electrostatically defined graphene quantum dots, to investigate the magnetic-field responses of artificial relativistic nanostructures.
Trapped electrons traveling in circular loops at extreme speeds inside graphene quantum dots are highly sensitive to external magnetic fields and could be used as novel magnetic field sensors with unique capabilities. Although graphene electrons do not move at the speed of light, they exhibit the same energy-momentum relationship as photons and can be described as "ultra-relativistic." When these electrons are confined in a quantum dot, they travel at high velocity in circular loops around the edge of the dot.
