AMOLED
An AMOLED panel produces visible colour by passing current through red, green, and blue organic-light-emitting-diode sub-pixels, each driven by 2–7 thin-film transistors per pixel that latch the desired brightness for one frame. Common AMOLED examples: Samsung Display M-series for smartphones, LG WOLED for televisions.
On a glass or polyimide substrate, an array of LTPS or oxide TFTs forms a backplane; on top of that, evaporated organic emissive layers (host + dopant) are sandwiched between an ITO anode and a metal cathode. When the row scan transistor is selected, the data voltage charges a storage capacitor that biases a drive transistor; the drive transistor then sources current through the OLED stack, which emits light proportional to current. Black pixels simply pass zero current — no backlight to leak.
In plain terms
A grid of millions of tiny coloured candles, each with its own dimmer switch. Where a candle is unlit, the area is genuinely dark — not 'shaded by a curtain' as in a backlit LCD.
Why designers use it
- Achieve infinite contrast ratio for HDR video without local-dimming-zone halos.
- Hit sub-millisecond pixel response for 120 Hz+ gaming and AR/VR low-persistence modes.
- Save power on dark UI themes — black wallpaper draws near zero current.
- Build flexible or curved displays since the OLED stack tolerates polyimide bending radii under 5 mm.
Best for
- Smartphones
- OLED TVs
- Foldables
Key specifications
- Operating limits: Check the exact manufacturer's datasheet (A family name does not establish voltage, current, temperature or timing limits.)
- Pin assignment: Match the complete part and package code (A similar name or function does not guarantee the same wiring.)
- Mechanical fit: Use the exact package drawing (Check pad layout, dimensions and viewing direction before building.)
When not to use it
- Outdoor full-sun signage above 1500 cd/m² sustained — average pixel luminance limits and burn-in shorten lifetime.
- Static-content kiosks left on for years — differential-aging causes permanent image retention; mini-LED backlit LCD is safer.
Common mistakes
- Driving with a fixed-voltage source instead of a current source — OLED I-V drift over hours causes uneven luminance unless compensated by external current sensing or per-pixel TFT compensation.
- Ignoring burn-in mitigation in firmware — leaving a 100 % white logo on screen permanently dims those sub-pixels relative to the rest.
Where you will find it
- An iPhone 15 Pro uses an LTPO AMOLED panel from Samsung Display: each red, green, and blue sub-pixel is independently switched, so when the always-on display shows white text on a black wallpaper the unlit pixels draw zero current, preserving battery life that a backlit LCD would burn keeping the entire backlight on.
- An LG C3 OLED television uses a WOLED stack where every pixel has a white OLED behind a colour filter: in HDR scenes, individual pixels next to bright highlights remain at true black with no halo, because each pixel's drive transistor simply outputs zero current — physically impossible on a backlit panel where the LED backlight always leaks some light through the LCD.
- A Samsung Galaxy Z Flip 5 uses a foldable AMOLED panel built on polyimide substrate: the stack survives 200 000 fold cycles at a 2 mm bend radius because the organic layers and oxide TFTs are thin and ductile, while a glass-based LCD with backlight would shatter at the hinge.
A short history
The organic light-emitting diode (OLED) was first demonstrated in 1987 by Ching Wan Tang and Steven Van Slyke at Eastman Kodak, who built a practical thin-film electroluminescent device from organic compounds. Pioneer Corporation produced the first commercial OLED product—a car-stereo display—in 1997. Active-matrix OLED (AMOLED) displays, which use a thin-film transistor backplane to individually control each pixel, were developed in the 2000s and brought unprecedented contrast ratios and response times to mobile screens. Today AMOLED panels power billions of smartphones, delivering pure blacks and vivid colour impossible in conventional backlit LCD displays.