What is a quantum dot?
A quantum dot is a semiconductor nanocrystal - a particle so small (2–10 nanometers) that quantum mechanical effects control its behavior. When excited by light, a quantum dot emits light at a precise wavelength determined by its size. Bigger dots emit red; smaller dots emit green; the very smallest emit blue.
This size-tunable emission is what makes quantum dots valuable for displays. Traditional phosphors have relatively broad emission spectra - they emit a wide spread of wavelengths around their peak. Quantum dots emit an extremely narrow, precise peak. A quantum dot "red" is a purer red than any phosphor red.
How quantum dot displays work
Current QLED displays use quantum dots as a color conversion layer, not as self-emissive pixels. A blue LED backlight excites the quantum dot film:
The result is a white backlight with narrow, precise red, green, and blue peaks. This maps efficiently onto the three color filters in an LCD, producing wider color gamut and more saturated colors.
QLED vs OLED: the marketing confusion
Samsung markets its high-end LCD monitors as QLED. LG markets OLED TVs with a QD layer as "QD-OLED." The naming is confusing.
| Technology | Backlight | Contrast | Color |
|---|---|---|---|
| Standard LCD | White LED | Moderate | Good |
| QLED (LCD + QD) | Blue LED + QD film | Same as LCD | Excellent |
| QD-OLED | Self-emissive OLED + QD | Infinite | Outstanding |
| OLED (W-OLED) | White OLED + CF | Infinite | Good–Great |
The key point: QLED is still LCD. It cannot match OLED for contrast or local dimming precision. But its color volume - brightness at saturated colors - exceeds standard OLED. At high peak brightness (800+ nits), QLED can display more vivid, bright, saturated colors than OLED.
What it means for you
QLED monitors are excellent for:
OLED is better for: