OLED manufacturers take you to understand the principle of organic EL illumination, organic EL, is the abbreviation of (Organic Electro-Luminescence: OEL, organic EL), meaning the electronic version of organic light. Although the definition is very general, it has a wide range of contents, such as organic light-emitting diodes, luminescent polymers, and the like, which are collectively referred to as all organic substances that use physical luminescence. The principle is almost the same as that of the LED, except that it uses an organic compound with a diode function. So, simply say the difference between the two
Now, the mainstream organic EL technology was discovered in 19 years by STeven Van Slyke of Kodak, a large-scale film company in the United States.
The principle of luminescence of organic EL is very similar to that of LEDs. After the voltage is applied to the cathode and anode of the material, movable electrons and cations are generated between the two poles. The electrons and the yang are moved to the anode and the cathode respectively due to the action of the electric field, leaving the two poles and bonding in the intermediate layer (light-emitting layer) of the composite material. The combination of electrons and cations produces energy that causes the outermost electrons of the material to be excited across the outer electron orbit. Because it is only excited, the outermost electron orbit is unstable, and the outermost electrons will immediately return to the original orbit, which will release excess energy in the form of light. From this point of view, organic EL and LED are the same. However, the material of the organic EL is a composite material, that is, a plurality of materials are thinned together. The cathode material is a metal which is easy to release electrons, and is mostly a metal film such as aluminum, silver magnesium alloy or calcium; the anode is an oxide capable of releasing a cation, such as ITO, a transparent metal oxide film.
Luminescent material and method of generating the same
The main part of organic EL is the luminescent material layer. After many experiments, the luminescent materials are roughly divided into two major categories: high molecular compounds and low molecular compounds.
Low molecular luminescent materials mainly include fluorescent materials and phosphorescent materials.
Fluorescent materials are easy to produce three primary colors (red, green and blue), and the price, life and processing are very convenient. It is a preferred low molecular luminescent material. The luminous efficiency of phosphorescent materials is much higher than that of fluorescent materials, but the luminous efficiency is reduced with the increase of current, the life is not high, the purification is difficult, and the blue spectrum is not complete, which is still less than fluorescent materials, which remains to be studied and developed.
Compared with polymer luminescent materials, the biggest problem with low molecular luminescent materials is the difficulty in processing. In particular, it cannot cope with large-scale production. Since the materials are attached to the surface of glass or transparent polymers in the form of thin films, the polymer film technology and surface treatment technology far exceed the low molecular weight. In addition, the potential of polymer luminescent materials is also very large, and many new materials will be born through continuous experimental research.