LED White Lighting
1. What are White LEDs?
White light LED (White Light-Emitting Diodes) is an electronic component that emits light through semiconductor materials. Its core function is to directly convert electrical energy into white light energy. It has the characteristics of high energy efficiency, long life, and small size. Since the breakthrough of blue light LED technology in the 1990s, white light LED has gradually replaced traditional light sources and become the mainstream technology in the field of lighting and display.
2. What is the Technical Principle of White LEDs?
1) Luminescence Mechanism
White light LED is based on the electron-hole recombination luminescence principle of semiconductor PN junction: when current passes through, electrons and holes combine at the PN junction, release energy, and radiate in the form of light.
2) White light synthesis method
Blue light LED + phosphor: blue light (about 460nm) excites yellow phosphor (such as Ce), and white light is formed after mixing.
Three primary color mixing: red, green, and blue LEDs are combined to produce white light through proportional adjustment.
3. What is the Technical Performance of White LEDs?
1) Key Technologies
The application of nitride semiconductor materials (such as InGaN) has promoted the commercialization of blue LEDs.
Single-layer luminous layer (SEL-WLED): Multi-wavelength emission is achieved through a single material, simplifying the device structure and improving efficiency.
2) Performance Parameters
Brightness: In lumens (lm), the light efficiency of white LEDs has increased from 5lm/W in the early stage to 80~100lm/W.
Color temperature: Adjusted by phosphor formula or three-primary color ratio, the range covers warm white to cold white (unit: K).
4. What are White LEDs Used for?
Display Backlight
LCDs of mobile phones, tablets, TVs, and other devices widely use side-emitting white LEDs as backlight sources.
General Lighting
Gradually replace incandescent and fluorescent lamps in scenes such as indoor lamps, automotive lighting, and flashlights.
Special Scenes
Ultraviolet LEDs combined with phosphor technology have expanded applications such as medical sterilization and industrial testing.
5. What are the Advantages and Limitations of White LEDs?
1)Advantages
High energy efficiency: Direct conversion of electrical energy into light energy, with efficiency far exceeding that of traditional light sources.
Long life: Up to 100,000 hours (about 50 °C environment).
Small size: Suitable for miniaturized design, such as chip-level integration.
2)Limitations
Drive voltage requirements: Need to be used with a transformer, and inferior accessories are prone to damage.
Color reproduction: The color rendering index of the early phosphor solution is low, and the cost of the three-primary color solution is high.
6. Technological Evolution of White LEDs
Development History: From monochrome LED to white light LED, the technical nodes include the commercialization of blue light LED (1993), phosphor optimization (after 2000), and single-layer luminous layer technology breakthrough (after 2020).
Future Direction: Focus on material innovation (such as perovskite) and integration technology (chip-level drive circuit) to further improve efficiency and reduce costs.