Analysis of the display principle of OLED display

Organic light-emitting diodes take advantage of the property of electrons to emit light: when an electric current passes through it, certain materials emit light. And from every angle, they are clearer than LCDs.

OLED display principle

In its simplest form, an organic light-emitting diode consists of a layer of light-emitting material, embedded between two electrodes. When a voltage is applied, the carriers move through the organic layer until the electron holes recombine, thus achieving energy conservation and releasing the excess energy in the form of light pulses. At this time, one of the electrodes is transparent and the emitted light can be seen. It is usually composed of indium tin oxide (ITO).

OLED display materials

The color of the light depends on the material. One method works with small molecular layers, such as aluminum oxide. Another method is to embed the activated pigment into long polymer chains, which are very easy to dissolve and can be made into coatings.

OLED is more efficient

The electron flow and carriers are usually not equal. This means that when the dominant carrier passes through the entire structure layer, it will not encounter electrons coming from the opposite direction, which consumes a lot of energy and has low efficiency. If one organic layer is replaced by two different organic layers, a better effect can be achieved: when the boundary layer of the positive electrode supplies carriers, the negative side is very suitable for transporting electrons. When the carriers pass between the two organic layers, they are blocked until carriers moving in the opposite direction appear, which significantly improves the efficiency. The thin boundary layer recombines to produce a small bright spot, which can emit light. If there are three organic layers, one for transporting electrons, one for transporting carriers and one for emitting light, the efficiency will be even higher.

OLED emits light, while LCD does not emit

light The biggest difference with liquid crystal displays (LCD) is that organic light-emitting diodes are the light source themselves. In LCD displays, the tiny liquid crystals change direction due to different input voltages. They let through/block the white light emitted by the background light source. This principle also limits the viewing angle. The effect is very poor or not visible from the side. LCD displays can have pixel errors due to wrong color emission, but such errors are almost non-existent in organic light-emitting diodes.

Active array or passive array

Like LCDs, OLEDs also come in active and passive arrays.
In passive array OLEDs, the position of the pixel is displayed by the number of rows and columns, which is affected by voltage. In active array OLEDs, the electron return area serves as the photosensitive substrate, and each pixel can be controlled by at least two crystals.