How Does OLED Work?
Jun 24, 2025
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Technology Origin: In 1987, Dr. Deng Qingyun of Kodak discovered that organic materials can emit light efficiently under the action of an electric field, which opened up the development of OLED display technology.
Basic structure and light-emitting principle
Structural composition: It consists of a transparent conductive anode (such as ITO), an organic functional layer (hole transport layer HTL, light-emitting layer EML, electron transport layer ETL) and a metal cathode.
●Light-emitting process: When current passes through, the anode injects holes and the cathode injects electrons. The two combine in the light-emitting layer to form excitons, which excite organic molecules to release photons; different organic light-emitting materials produce red, green and blue primary colors, and control the combination of pixel light emission to present a color picture.
●The core difference from LCD: OLED is self-luminous, and each pixel controls the light emission independently, without the need for a backlight module; when displaying black, the pixel is turned off, so it can achieve extremely high contrast, presenting deep black and bright white.
Technology development iteration
●Process evolution: Early small molecule OLEDs used vacuum thermal evaporation technology for high-end products; polymer OLEDs (PLEDs) used solution spin coating or inkjet printing technology, which is suitable for large-area flexible display mass production.
●Technical solution: To solve the problem of short life of blue organic materials, the industry has developed white OLED + color filter (WOLED), quantum dot color conversion technology (QDOLED), etc.
Application scenarios
●Consumer electronics: Samsung Galaxy series mobile phones use flexible OLED screens, and LG launched a 48-inch OLED e-sports display with a response speed of 0.1ms and a refresh rate of over 120Hz.
●Automotive field: Mercedes-Benz S-Class curved OLED central control screen, BMW AR-HUD head-up display, using OLED's thin and bendable characteristics to innovate in-car design.
●Emerging fields: Applied to wearable devices, transparent window advertising screens, etc.
Challenges
Lifespan: Organic materials will decay if they continue to emit light, with a typical lifespan of 30,000 to 50,000 hours. The brightness may decrease after 5 to 8 years of continuous use, and there is a risk of screen burn-in when static images are displayed for a long time.
Cost dilemma: Large-size OLED panels rely on vacuum evaporation technology, with equipment investment exceeding US$10 billion. The yield rate decreases as the size increases, but with the commissioning of domestic manufacturers' 10.5-generation lines, the price of OLED TVs above 55 inches has dropped by 40% compared to 2018.