Home : Hardware Terms : OLED Definition


Stands for "Organic Light Emitting Diode" and is pronounced "oh-led." OLED is a type of flat screen display similar to an LCD that does not require a backlight. Instead, each LED within an OLED panel lights up individually.

An OLED screen has six layers that work together to produce color images. These layers include the following, from bottom to top:

  1. Substrate - the foundational structure that supports the panel; typically made out of glass or plastic
  2. Anode - a transparent layer that removes electrons when electrical current flows through it
  3. Conductive Layer - contains organic molecules or polymers such as polyaniline that transfer current to the emissive layer
  4. Emissive Layer - contains organic molecules or polymers such as polyfluorene that light up when current is passed through them
  5. Cathode - injects electrons into the other layers when current flows through it
  6. Cover - the top protective layer of the screen; typically made out of glass or plastic

How does an OLED work?

OLEDs display light using a process called electrophosphorescence. While this may sound like an intimidating term, the process is relatively simple. Electrical current flows from the cathode (negatively charged) to the anode (positively charged), causing electrons to move to the emissive layer. These electrons find "holes" (where atoms missing electrons) in the conductive layer and produce light when they fill these holes. The color of the light depends on the organic molecule that the current passed through in the emissive layer.

Since the diodes in OLED displays light up individually, there is no need for a backlight. This means OLEDs can have darker blacks than LED/LCD displays and use less electricity. They are also thinner and may be curved or even bendable. While OLEDs have many advantages over LED/LCD displays, it has been expensive to produce large, reliable OLED screens. Therefore, OLEDs have been more common in small electronics, such as smartphones and tablets. As OLED production costs decrease and reliability increases, the technology will become more commonly used in larger screens, such as televisions and computer monitors.

Updated: September 30, 2014

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