MicroLED, also known as µLED, has prominent flat-panel display technology. MicroLED displays are made of arrays of microscopic LEDs. MicroLEDs provide better contrast and energy efficiency in comparison with LCD displays. MicroLED provides reduced energy requirements offering an infinite contrast ratio. The nature of micro-LEDs being inorganic gives them a longer lifetime than OLEDs. In 2000, the new technology of micro-LED display was developed by the Texas Tech University professor Hongxing Jiang and Jingyu Lin. In 2012 the first micro-LED TV was demonstrated by Sony which was called the Crystal LED display.
Micro-LED displays are small and thinner compared to other LEDs. The range of individual micro-LED is 1- 10µ m. The substrate is either transparent or opaque and also flexible, made of hard material. By the process of physical vapor deposition, a protective layer is formed on top of two electrodes. The structure is a PN junction diode. It provides more than 120% NTSC color saturation. The three major methods for the production of micro-LEDs are
- Chip Bonding
- Wafer bonding
- Thin Film Transfer
Chip bonding: In this technique, the LEDs are split into Micro size LED chips by using SMT or COB technology, and then it is finally bonded into the display substrate one by one.
Wafer bonding: In this technique, the EPI wafer films are used to form a micro-grid LED film structure. It after forms the display pitch once the structure becomes solid.
Thin-film structure: In this technique LED substrate is stripped away in order to replace the temporary EPI wafer forming wafer structure.
Among these three techniques, the thin film transfer technique is low cost when compared to chip bonding and wafer bonding.
Challenges faced during manufacture include color conversion, light extraction and beam shaping, massively parallel and high accuracy pick and place technology, backplane hybridization, defect management and testing
ADVANTAGES OF USING MICRO LED
- Low power consumption
- High dynamic range
- Long lifetime
- Environmental stability
- Fast refresh rates
- Flexible backplane
- High pixel density
DISADVANTAGES OF USING MICRO LED
- Difficult to manufacture in large volume
APPLICATIONS OF MICRO LED
- Virtual reality
- Mixed reality
- Automotive head-up display
Micro led is a new display technology with high performance and higher contrast when compared to other technologies. There are still many manufacturing challenges that can be addressed as cost-effective and high volume manufacturing disadvantages. Micro LEDs can perform better than OLEDs but it can’t completely displace the LCD and LED