You must frequently see the term "LED", which is only one letter different from OLED, but in fact the two describe completely different things. We all know that the LCD panel is emitted by the backlight, through the refraction of liquid crystal molecules to produce a variety of different colors, liquid crystal molecules themselves can not emit light, and LED only refers to the backlight. OLEDs, on the other hand, emit light themselves, so they don't need a backlight. LED uses metal materials, and OLED uses organic materials; OLED is more advanced, it can emit light autonomously without lighting, the contrast is better, usually used, LED is to have a backlight to see things.
First, LED light-emitting principle and luminescent materials:
Semiconductor materials have a very interesting property, which is the so-called carrier; Carriers are divided into two categories: one is electron, negatively charged; The other type is electric holes, which are positively charged. The principle of LCD luminescence is that two carriers can be combined under certain conditions, and the released energy is released in the form of photons and emits light. It will depend on the different materials, the electrons and the hole occupy different energy levels, that is to say, the relative energy contact height difference between the electrons and the hole is to determine the level of energy emitted by the combination of the two carriers, and photons with different energies can be produced, so as to control the wavelength of the light emitted by the LED, that is, the spectrum or color.
The materials used in LEDs are mainly 3A-5A element compound semiconductors (such as GaP, GaAs, GaN, AlInGaP, etc.). As for why it emits different colors of light, it has to be the material of the LED itself, for example: red light uses AlInGa (aluminum gallium carbide), green light uses GaP (gallium phosphide), blue light uses ZnS (zinc sulfide) or GaInN (gallium indium nitride)... Wait a minute.
LEDs are distinguished by their light-emitting wavelengths, which can be roughly divided into visible diodes and infrared light-emitting diodes. Its luminescence principle is to use the semiconductor electrons and holes combined, the released energy in the form of photons and luminescence, and the materials used in light-emitting diodes are compound semiconductors of 3A and 5A group elements, such as: GaAs, GaP, AlGaP, AlInGaP, etc., and its luminescence wavelength and brightness will vary depending on the material used.
Second, OLED - organic light-emitting diode
At present, the materials used in light-emitting diodes are inorganic semiconductor materials, which are difficult to apply to large areas and require high-resolution components (EX: screen), to solve these problems rely on new organic semiconductor materials (that is, hydrocarbon-containing materials), coated on conductive glass sheets, through electric current, can emit a variety of different wavelengths of light.
1. OLED luminescence principle
The principle of organic light-emitting is similar to the light-emitting principle of light-emitting diodes, and the same uses material characteristics to combine the electron hole on the light-emitting layer, and the electrons are lowered from the excited state back to the ground state, and the excess energy is released in the form of waves to achieve the function of luminescence. Hence the name OLED and PLED. (OLED is an organic electric excitation photodiode for small molecules, and PLED is an organic electric excitation photodiode for polymers.) )
2. OLED structure
The basic structure diagram of organic light-emitting diode is shown in the figure below, which also uses the characteristics of the material to combine the electron hole on the light-emitting layer, and the electron is reduced from the excited state back to the ground state, and the excess energy is released in the form of waves, so as to achieve the generation of light-emitting components with different wavelengths. OLED is used to inject electrons and holes between two electrodes, respectively, and uses it
The excitation of organic molecules achieves the function of luminescence. Among them, the anode ITO conductive glass film is attached to the glass or transparent plastic substrate by evaporation, and the cathode contains Mg, Al, Li and other metals. Between the two electrodes is a plurality of organic film formed by the light-emitting area, including the hole injection area, the hole transfer area, the organic light-emitting layer and the electron transport layer, in the actual mass production, considering different needs, and sometimes containing other different films.
3. OLED colorization method
At present, organic light-emitting diodes are the most mature technology with green light, and blue and red light are still to be commercialized. The color of organic light-emitting diode display is divided into monochrome, multi-color and full-color, multi-color is composed of several monochrome display areas, each area is still monochrome; Full color is composed of repeating pixels of red, green, and blue light, and the finer the pixel size, the higher the resolution. In the application of displays, full color is necessary for market success.
4. What are the advantages of OLED technology?
OLED is an organic light-emitting diode, also known as organic electric laser display Because it has the characteristics of thinness and power saving, LED screen has many incomparable advantages of LCD, so it has also been optimistic about the industry.
5. OLED application
OLED is currently mainly used in automotive displays, mobile phones, game consoles, handheld portable small computers, personal digital assistants (PDAs), car audio and digital cameras... Wait. In the future, it will develop high-fluorescence efficiency materials, the production of 5-inch full-color displays, the development of new application fields of organic components, and high-resolution full-color small-size displays, such as smart mobile phones.