A KAIST research team developed a low-cost production method for flexible, verticle blue thin-film micro LEDs (f-VLEDs). Professor Keon Jae Lee from the Department of Materials Science and Engineering and his team developed the one-time transfer method for fabricating an array of thousands of blue, gallium nitride (GaN) micro LEDs (thickness < 2 μm) on plastics.
The blue GaN f-VLEDs achieved optical power density (~30 mW/mm2) three times higher than that of lateral micro LEDs. Also, the team was able to reduce the heat generation resulting in an increased projected device lifetime of about 100,000 hours.
Arrays of f-VLEDs Allow Flexible Attachment
These blue f-VLEDs could be conformally attached to the curved skin for wearable devices and even implanted in brains. Also, the team reported that the micro LEDs could be powered stably with wirelessly transferred electrical energy.
Micro LEDs are expected to take over from AMOLED displays, with very low power consumption, faster response, and design flexibility. However, to scale up to larger displays and TVs, the fabrication technology will need to be able to transfer millions of red, blue, and green micro LEDs.
Professor Lee said, “For future micro LEDs, the innovative technology of thin-film transfer, efficient devices, and interconnection is necessary. We plan to demonstrate a full-color micro LED display in smartwatch sizes by the end of this year. ”
This research led by a PhD candidate Han Eol Lee was published in the June 2018 issue of Advanced Materials.
Lee, H. E., Choi, J., Lee, S. H., et al. “Monolithic Flexible Vertical GaN Light‐Emitting Diodes for a Transparent Wireless Brain Optical Stimulator” Advanced Materials, June 2018. https://doi.org/10.1002/adma.201800649