OLED and AMOLED technology

An OLED (organic light-emitting diode) is a display technology in which each pixel emits its own light from a thin film of organic compounds placed between two electrodes. When a voltage is applied, current flows through the organic layers and they glow, a process known as electroluminescence. Because every pixel is its own light source, an OLED display needs no separate backlight, unlike a liquid-crystal display (LCD), which relies on a backlight shining through a layer of liquid crystals that act as shutters.

The self-emitting nature of OLEDs gives them several distinctive qualities. A pixel can be switched off completely to produce true black, which yields very high contrast, and the panels can be made extremely thin and even flexible because they do not need the bulky backlight assembly of an LCD. Viewing angles are wide and response times are fast. The main historical challenges have been manufacturing cost and the differing lifetimes of the red, green and blue organic materials.

AMOLED stands for active-matrix OLED, the variant used in most phone and television screens. Here a thin-film-transistor backplane provides an active-matrix circuit that drives each pixel independently and holds its state, allowing large, high-resolution panels with good brightness and refresh rates. The simpler passive-matrix arrangement, by contrast, scans rows and columns and suits only small, low-resolution displays. AMOLED is therefore the dominant form in modern consumer devices.

Frequently asked questions

How does an OLED differ from an LCD?

Each OLED pixel emits its own light, so no backlight is needed. An LCD instead uses a backlight shining through liquid-crystal shutters, which makes deep blacks and very thin panels harder to achieve.

What does AMOLED mean?

AMOLED is active-matrix OLED, which uses a thin-film-transistor backplane to drive each pixel independently. This allows large, high-resolution, bright displays such as those in phones and televisions.

Why can OLED displays show true black?

Because each pixel is a separate light source, a pixel can be turned off entirely to emit no light, producing true black and very high contrast.