Researchers in the industry and in the academic field have dedicated their efforts to overcome the difficulties of Micro LED display technologies. Currently the bottlenecks of the technology lie in six major areas including mass transferring process, the production of epitaxial wafer, method for full-color display, driver IC design, backplanes and testing and repair technology.

One of the articles awarded with honorable mention in the Micro LED Technology Research Contest hosted by LEDinside has focused on the method for full-color display. The article, titled “Quantum Dots Based Full-color Display on MicroLED Technology,” was contributed by a research team consisting of scholars from National Chiao Tung University in Taiwan, Hong Kong University of Science and Technology in Hong Kong and Southern University of Science and Technology in China.

The article illustrates the research result of the team, which combined UV Micro LED array, photoresist mold, and RGB quantum dots to demonstrate a full-color Micro LED display. Conventionally, displays combine RGB LEDs to achieve full color. However, the method is extremely challenging for Micro LED display as a huge number of tiny sized RGB LEDs are required and it is difficulty to efficiently assemble the three color LEDs. Moreover, the currents needed to drive the LEDs are different among the three colored LEDs, making it even more complicated to design the circuit on the substrate for Micro LED display.

(Image: Lin et al. 2018)

Excitation sources such as UV Micro LED or blue Micro LED are often used with color conversion materials to achieve full color. In the research, the team utilized UV Micro LED and quantum dots (QD) as they found that UV Micro LED with RGB QDs has higher quantum yields than blue Micro LED. In addition, when fabricating Micro LED display, the team added a photoresist mold to the UV Micro LED array in order to reduce the optical cross-talk effect. Meanwhile, Aerosol Jet technology was applied for dispensing the RGB QDs on Micro LED array. According to the research, with these methods, Micro LED displays with better quality can be produced.

(Image: Lin et al. 2018)

See full paper: Quantum Dots Based Full-color Display on MicroLED Technology