Although both OLEDs and LCDs are utilized in display devices, they present display information differently. An OLED display is an emissive display (self-illuminating) that does not require a backlight. This makes them easier to manufacture, significantly thinner, and more efficient than LCDs (which do require a white backlight). The simpler design of these displays allows for ultra-thin, flexible, foldable, and transparent screens. Our company Dakenchem is a professional OLED film formulation service provider in China. Check this post for more information.
Image quality has been improved in OLEDs with better contrast, higher brightness, a fuller viewing angle, a larger color range, and significantly faster refresh rates. On a per-pixel basis, only OLED technology is capable of absolute blacks and exceptionally bright whites. LCD is not capable of such feats due to backlighting. Moreover, very low power consumption, high durability, and the ability to perform in a broader temperature range are some other features possess by OLED displays. Likewise, OLEDs outperform LCDs by a wide margin.
OLED films are made up of a sequence of organic thin films placed between two conductive thin-film electrodes. At least one of the electrodes must be transparent for light to escape from the device. Holes and electrons transfer from the electrodes into the organic thin films under the influence of an electrical field and recombine in the emissive zone to generate excitons when electricity is supplied to an OLED. When excitons are generated, they relax to a lower energy level by emitting light and unwanted heat. An OLED structure is broken down as follows:
The substrate, which is often made of glass or metal, serves as the base of the OLED. The organic layers that fabricate the OLED device are injected with holes by the positively charged anode. Optical clarity, chemical stability, and electrical conductivity of anodes are all considered while selecting them.
The hole injection layer and the hole transport layer are responsible for injecting holes further into the device and aiding hole transportation. The electron transportation layer, as its name implies, facilitates electron transportation. Once the holes and electrons are confined on the emissive layer, they eventually join and release light. Here electrical energy is transformed directly into light. The cathode is negatively charged.
The organic layers that fabricate the OLED device are injected with electrons by the cathode. The quantity of electric current provided by the electrodes controls the intensity of the light emitted. Furthermore, the color of the light is regulated by the type of emissive material utilized.
In the formulation of OLED, a variety of chemicals are employed. Organometallic chelates such as Alq3, fluorescent and phosphorescent dyes, and conjugated dendrimers are extensively employed in OLEDs. A wide range of materials is used for their charge transport characteristics, including triphenylamine and derivatives (CAS NO. 201802-67-7), which are often used as materials for hole transport layers. Polyaniline (CAS NO. 25233-30-1) is a conductive polymer used in OLEDs.
In the OLED film formulation process, there are three approaches to apply organic layers to the substrate. VTE (Vacuum Thermal Evaporation) is an inefficient and costly process. Here, organic molecules are gradually heated in a vacuum chamber and condensed onto cooled substrates as thin films. OVPD (Organic Vapor Phase Deposition) method uses a carrier gas to transfer evaporated organic molecules onto cooled substrates via a low-pressure, hot-walled reactor chamber, condensing into thin films. The use of a carrier gas improves efficiency and lowers the cost of manufacturing OLEDs. The most cost-effective approach is inkjet printing. Here, with the use of inkjet technology, OLEDs can be sprayed onto substrates. This resembles with ink spraying technique used in printers Reference: https://www.nature.com/articles/s41598-019-44824-w
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