OLED Illumination: The Basics

What is OLED?

OLED stands for organic light-emitting diode.OLED utilize a phenomenon in which certain types of organic matter emit light in response to an electric current. Organic matter, which is what plants and animals are made of, exists everywhere on Earth.

Around 25 years ago, American researchers succeeded in producing light from an ultra-thin layer of organic material. This technology is now used in OLED displays and light sources.

How are OLED materials made?

OLED layers have a simple composition, produced by layering ultra-thin layers of organic matter, each of which has a different function. The completed organic layer has a thickness on the order of hundreds of nanometers — less than 1/1000 the diameter of hair.

The thin OLED layer is then sandwiched between positive and negative electrodes, and gives off light when a current is applied.

Why do OLED materials give off light?

Current is applied across the organic material, such that one electrode is negatively charged and the other positively charged.
The process can be described as injection of electrons at the negative electrode and electron holes at the positive electrode.

When the electrons and holes recombine in the emissive layer, the organic matter of the layer enters an excited (high-energy) state. As the layer returns to a low-energy state, it emits energy in the form of light.
The following video gives a simple depiction of this process.

Current is applied to the organic material, with positively charged electron holes and negatively charged electrons injected from either side. Current is applied to the organic material, with positively charged electron holes and negatively charged electrons injected from either side. Current is applied to the organic material, with positively charged electron holes and negatively charged electrons injected from either side. Current is applied to the organic material, with positively charged electron holes and negatively charged electrons injected from either side. Current is applied to the organic material, with positively charged electron holes and negatively charged electrons injected from either side. Electron holes and electrons meet and recombine in the emissive layer. Electron holes and electrons meet and recombine in the emissive layer. Electron holes and electrons meet and recombine in the emissive layer. Electron holes and electrons meet and recombine in the emissive layer. As a result, molecules in the organic emissive layer enter an excited (high-energy) state. When the energy level of the organic layer relaxes, energy is emitted in the form of light.

Differences between OLED displays and OLED lighting

  OLED displays OLED lighting
Brightness Displays produce light appropriate for people to look at directly.
If the light is too bright,it will tire out the viewer's eyes.
Unlike displays,light sources are not meant to be looked at; rather,they illuminate what people want to see.
Therefore,they must be brighter than displays.
Color Displays use the three primary colors-red,green,blue.Images can be displayed in full color by combining the primary colors. In order to show objects in their true colors,basically the light is white,like sunlight.
Working
principle
In order to form images,individual pixels are switched on or off. Unlike displays,lighting does not use small pixels.The entire display is switched on or off.