What are quantum dots and why are they important? Quantum dots are nanometer-sized, inorganic crystals that produce light at different wavelengths – i.e. colors – when stimulated with photons or electrons.
There are two basic types of QDLED display:
- Photo-emissive: In the photo-emissive type, the quantum dot particles are applied to a layer that converts the backlight into different wavelengths or colors. The advantage compared to RGB color filters is that the quantum dots allow for greatly improved display brightness and color gamut. This is achieved by reducing color crosstalk and light losses. Normally, the backlight is provided by LEDs on an LCD panel. This technology is currently used by Samsung and is more commonly known as QLED.
- Electro-emissive: Electro-emissive – or electroluminescent – quantum dot displays is an experimental display technology that is currently not commercially available. It’s based on quantum-dot light-emitting diodes, i.e. QD-LED (also known as ELQD, EL-QLED, QDEL). These displays have more in common with OLED (organic light-emitting diode) and MicroLED displays than with Samsung’s QLED display technology. Light is produced directly in each pixel by applying an electric current to the nano-particles. However, the particles, in this case, are inorganic. In theory, QD-LED displays could be large and flexible displays and would offer a longer life span than OLEDs.
Electro-emissive quantum dot displays also share other advantages with OLED in that they achieve perfect blacks and essentially infinite contrast. The QDLED technology is also an improvement over OLED, as they are capable of displaying wider color gamuts. They are also comparatively cheap to manufacture.
What is “Quantum Dot” in QDLED?
A quantum dot represents a nanoscale semiconductor structure, which is used to confine electrons in three dimensions. This it can be constructed from a cadmium selenide core which incorporates a zinc sulfide shell, in which electrons are excited to high energies, as they travel towards the ‘holes’ between the core and the shell, exciting the quantum dot that converts the energy received from the electron into visible light.
Quantum dot technology and the Quantum Light product platform was developed by the MIT-incubated nanotechnology company QD Vision Inc. and was designed for consumer electronics, including flat panel display, electronic signage and solid-state lighting manufacturers. The basic premise has been to outperform liquid crystal displays (LCDs), plasma displays, LEDs and organic LEDs (OLEDs), across the key performance categories of brightness, color purity, power conservation, and design flexibility.
QD Vision engineered quantum-dot-based nanocrystal solutions to emit light tuned to frequencies across the visible and infrared spectrum. Because quantum dot materials emit pure, finely tuned colors, the Quantum Light product platform provided better color saturation and color rendering than other technologies, without power consumption trade-offs. It is the only materials technology that can be designed to emit any color of light across the entire visible spectrum.
As the Quantum Light platform can directly emit light and color, using less power than other solutions, it’s an attractive option for clean-tech applications. In contrast, conventional LCDs – including QLED – utilize LED backlights that are filtered to achieve the desired colors, and consume several times the power of electro-emissive quantum dot-based displays.
QD Vision’s quantum dot inks can be applied to virtually any substrate using a wide range of well-known printing and coating techniques. The Quantum Light product platform therefore opens up new possibilities in the design and manufacture of consumer and industrial products, including the potential for displays, lighting fixtures, and signage with very large areas, thin and contoured forms, or transparent backgrounds.