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Everyday Tech/How OLED & MicroLED Displays Work
Everyday TechTechnical8 min

How OLED & MicroLED Displays Work

Organic self-emissive subpixels delivering true infinite contrast without a bulky backlight.

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OLED SUBPIXEL CROSS-SECTION (200nm Stack)True Black & Self-Emissive ElectroluminescenceGlass & PolarizerCathode (Mg/Ag)ETL (Electron Trans.)EML (Emissive Layer)HTL (Hole Trans.)Anode (ITO Transp.)LTPO TFT BackplaneRED (620nm)Cathode (-)e- InjectionEXCITON (hν)h+ InjectionAnode (+) ITOLTPO Gate: 3.3 VCurrent: 1.4 μAGREEN (530nm)Cathode (-)e- InjectionEXCITON (hν)h+ InjectionAnode (+) ITOLTPO Gate: 3.3 VCurrent: 1.4 μABLUE (460nm)Cathode (-)e- InjectionEXCITON (hν)h+ InjectionAnode (+) ITOLTPO Gate: 3.3 VCurrent: 1.4 μATRUE BLACKCathode (-)e- Injection0 PHOTONSh+ InjectionAnode (+) ITOLTPO Gate: 0.0 VCurrent: 0 μA

Step 11. TFT Backplane Drive Current

TFT transistor gates regulate micro-ampere current to target subpixel.

LTPO thin-film transistors supply precision driving currents to the transparent ITO anode.

Step 1 of 4How OLED & MicroLED Displays Work
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Target Audience:Curious Beginners
Unlike LCD screens that use a giant backlight, every single microscopic pixel on an OLED screen produces its own light and can turn completely off for true black.

Key Takeaways

  • OLED = Organic Light-Emitting Diode.
  • Each pixel is its own tiny lightbulb.
  • Black pixels are completely powered off (0 Watts, True Black).

Millions of Tiny Lightbulbs

On an older LCD TV or laptop, a big bright white backlight shines through color filters. Even when showing black, light leaks through, making blacks look dark gray.

On an OLED screen, there is no backlight. Every single one of the 8,294,400 pixels (and their Red, Green, Blue subpixels) is an individual organic molecule that lights up with electricity. To show black, that pixel simply turns off!
Interactive Challenge+25 XP

Why do OLED displays achieve an 'infinite' contrast ratio compared to traditional LCD screens?