Quantum Dots
Quantum Dots: Definition, Graphene and Carbon Quantum Dots, and Applications
Quantum dots are nanocrystals a few nanometres in size that fluoresce with a size-dependent colour. This page covers low-toxicity carbon-based quantum dots (GQDs and CQDs), their applications and the products available.
- 2–10 nmtypical quantum dot size
- Blue & greenGQDs in water
- 0.01–1 mg/mLGQD concentration options
- Carbon-basedcadmium-free
What are quantum dots?
Quantum dots are semiconductor or carbon particles a few nanometres in size. At this scale electrons are confined (quantum confinement), so the energy absorbed and emitted depends on particle size. As a result quantum dots fluoresce brightly under UV light with a tunable colour.
Classic quantum dots such as CdSe are very bright but contain heavy metals. Graphene quantum dots (GQD) and carbon quantum dots (CQD) are carbon-based alternatives that are more environmentally benign, water-soluble and easy to functionalise, making them popular in sensing and biology research.
Carbon quantum dot applications
- Fluorescence sensors for metal ions (such as Fe³⁺, Hg²⁺) based on fluorescence quenching.
- Electrode modification for electrochemical sensors.
- Bioimaging and cell labelling.
- Photocatalysts and solar-cell sensitisers.
- Security and anti-counterfeiting inks.
- Colour-conversion layers in LEDs.
Quantum dot products
| Product | Best for | Price | Purchase |
|---|---|---|---|
| Blue GQDs, 1.0 mg/mL | High concentration for synthesis and modification | Rp 3.403.000 | Buy online |
| Blue GQDs, 0.1 mg/mL | Fluorescence sensing tests | Rp 3.403.000 | Buy online |
| Green GQDs in DI water, 1.0 mg/mL | Imaging and sensing with green emission | Rp 3.403.000 | Buy online |
| Carbon quantum dots (CQDs) | Sensors, photocatalysts, composites | Rp 3.403.000 | Buy online |
| Quantum dot microspheres 525 nm | Fluorescent labels for immunoassays | Rp 20.239.000 | Buy online |
| Magnetic quantum dot microspheres 615 nm | Magnetic separation with fluorescence detection | Rp 20.239.000 | Buy online |
Products are for research and laboratory use only, not for consumption or as finished cosmetic ingredients. Full specifications and SDS are on each product page.
Basic quantum dot characterisation
- UV-VisCheck absorption bands to estimate band gap and concentration.
- PhotoluminescenceMeasure emission at several excitation wavelengths; GQDs often show excitation-dependent emission.
- Quantum yieldCompare with a standard such as quinine sulfate.
- Size and structureTEM for size, FTIR and XPS for surface groups.
Frequently asked questions
What is the difference between graphene and carbon quantum dots?
GQDs have a nanoscale graphene structure (ordered sp² layers), while CQDs are usually spherical with a less ordered carbon core. Both fluoresce and are water-soluble.
Are carbon quantum dots safe?
They are generally considered less toxic than cadmium-based quantum dots, but still handle them as laboratory chemicals according to the SDS.
Which concentration should I choose?
A high concentration (1 mg/mL) is flexible because it can be diluted; lower concentrations are convenient for direct sensing tests.
Need help choosing?
Tell us about your samples, methods and budget. Our team will put together the equipment and supplies with a formal quotation.
