OLED manufacturers take you to understand the luminescence principle of organic EL, organic EL, is (Organic Electro-Luminescence: OEL, organic EL) abbreviation, meaning organic luminescence electronic version. Although the definition is very broad, it includes a very wide range, such as organic light-emitting diodes, light-emitting polymers, and so on, which use physical light-emitting phenomena. The principle is similar to that of LEDs, except that organic compounds with diode functions are used. So, simply talk about the difference between the two
Now, mainstream organic EL technology was discovered by STeven Van Slyke of Kodak, a large American hand film company, in 19 years.
The light-emitting principle of organic EL is very similar to that of LED, in that after the cathode and anode of the material are added to the voltage, electrons and cations that can move are generated between the two poles. Due to the electric field, electrons and anodes move towards the anode and cathode, respectively, leave the poles, and combine in the middle layer (light-emitting layer) of the composite material. The energy produced by the combination of electrons and yangs causes the outermost electrons of the material to be excited and cross into the outer electron orbital. Because it is only excitation, the orbital of the outermost electrons is unstable, and the outermost electrons will immediately return to their original orbit, which will release the excess energy in the form of light. From this point of view, organic EL and LED are the same. However, the material of organic EL is a composite material, that is, a variety of materials are filmed and superimposed together. Cathode materials are metals that are easy to release electrons, mostly aluminum, silver-magnesium alloy, calcium and other metal films; The anode releases oxides of impotents, such as ITO, a transparent metal oxide film.
Luminescent materials and generation methods
The main part of organic EL is the luminescent material layer, and after many tests and verifications, luminescent materials are roughly divided into two categories: polymer 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), in addition to the price, life, processing are very convenient, is a kind of low molecular weight luminescent materials. 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 as complete as fluorescent materials, and it remains to be studied and developed.
Compared with polymer luminescent materials, the biggest problem of low molecular luminescent materials is that they are difficult to process. In particular, it cannot cope with large-scale production. Since the materials are attached to the glass or transparent polymer surface in the form of films, the thin film technology and surface treatment technology of polymers far exceed that of low molecules. In addition, the potential of polymer luminescent materials is also very large, and with continuous experimental research, many new materials will be born.