A research team at the Korea Advanced Institute of Science and Technology (KAIST), South Korea, developed a low-cost production technology for thin-film blue flexible vertical micro LEDs (f-VLEDs). These blue f-VLEDs could be conformally attached to the curved skin and brains for wearable devices, and stably operated by wirelessly transferred electrical energy.
In CES 2018, micro LED TV was spotlighted as a strong candidate for replacing the active-matrix organic light-emitting diode (AMOLED) display. Micro LED is a sub-100 um light source for red, green and blue light, which has advantages of outstanding optical output, ultra-low power consumption, fast response speed, and excellent flexibility. However, the current display industry has utilised the individual chip transfer of millions of LED pixels, causing high production cost. Therefore, the initial market of micro LED TV will be estimated at around $100,000 for global premium market.
To widely commercialise micro LEDs for mobile and TV displays, the transfer method of thin film micro LEDs requires a one-time transfer of one million LEDs. In addition, highly efficient thin-film blue micro LED is crucial for a full-colour display.
According to the researchers, the blue GaN f-VLEDs achieved optical power density (around 30 mW/mm2) three times higher than that of lateral micro LEDs, and a device lifetime of 100,000 hours by reducing heat generation.
Professor Keon Jae Lee from the Department of Materials Science and Engineering and his team developed thin-film red f-VLED in previous projects. He said, “We plan to demonstrate a full-colour micro LED display in smart watch sizes by the end of this year.”
