KAIST Researchers Develop Flexible Vertical MicroLEDs they call f-VLEDs

A research team from the Korea Advanced Institute of Science and Technology (KAIST) has developed flexible vertical micro LEDs that the researchers are calling f-VLEDs. The researchers led by Professor Keon Jae Lee from the Department of Materials Science and Engineering and Professor Daesoo Kim from the Department of Biological Sciences used anisotropic conductive film (ACF)-based transfer and interconnection technology. The team also successfully controlled animal behavior through the optogenetic stimulation of the f-VLEDs.

The researchers note that Flexible micro LEDs have much potential for their use in next-generation display because of their fast response time, ultra-low power consumption, and excellent flexibility. However, much microLED technology has suffered from poor efficiency, the lack of interconnection technology for high-resolution microLED displays, and it is susceptible to heat degradation.

Team Created 50×50 Array of f-VLEDs

The research team has created new transfer equipment that uses the precise alignment of ACF bonding process for simultaneous transfer and interconnection. From this new equipment, the team has fabricated a (50×50) f-VLED array. These f-VLEDs (thickness: 5 ㎛, size: below 80 ㎛) reportedly achieved optical power density (30 mW/mm2) three times higher than that of lateral microLEDs. The team said they also reduced the heat generation within the thin film LEDs to improve the thermal reliability and lifetime.

Professor Lee said, “The flexible vertical micro LED can be used in low-power smart watches, mobile displays, and wearable lighting. In addition, these flexible optoelectronic devices are suitable for biomedical applications such as brain science, phototherapeutic treatment, and contact lens biosensors.”

Professor Keon Jae Lee recently founded a startup company FRONICS Inc. based on microLED and flexible electronic technology and is seeking global partnerships for commercialization. The result of the biomedical research using the microLEDs titled, “Optogenetic Control of Body Movements via Flexible Vertical Light-Emitting Diodes on Brain Surface” was published in the February 2018 issue of Nano Energy.

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