Apply materials to develop new Micro LED full-color technology

On May 13, foreign media reported that Applied Materials has launched a new method to create full-color Micro LED displays using innovative quantum dot (QD) technology.

The company's research team calls this new technology a full-color conversion approach, which combines UV Micro LEDs with red, green and blue quantum dots, which has more advantages compared with traditional full-color technology.

It is reported that there are currently three main methods to realize full-color Micro LED displays, one is to create them through native RGB Micro LEDs (Native RGB Micro LEDs), the other is to use hybrid structures (partial color conversion), and the third is to use full-color conversion.

Comparison of Micro LED full-color technology (Photo source: Applied Materials Company)

It is reported that although the native RGB method is simple to assemble, it faces problems of low luminous efficiency and complex backplane circuit design. Partial color conversion simplifies manufacturing complexity, but it damages color purity. Compared with the first two methods, Applied Materials Company is more optimistic about the full-color conversion method. By combining UV Micro LEDs and RGB quantum dots, it can simplify the manufacturing of full-color Micro LEDs, enhance color uniformity, and increase the number of pixels.

Specifically, Applied Materials uses 385 nm UV Micro LEDs as excitation sources to create cadmium-free and lead-free quantum dots, including red and green light quantum dots based on InP and blue quantum dots based on ZnSe. These quantum dots have significant ultraviolet light absorption and no environmental pollution characteristics, are stable during the integration process, and demonstrate their potential for high-performance displays.

In the manufacturing process of quantum dot pixels, Applied Materials Company mainly uses photolithography and inkjet printing methods. Among them, lithography technology is suitable for the manufacturing of displays with high PPI;

Large size displays use inkjet printing technology to ensure accurate placement of quantum dots. To this end, the research team has also developed an innovative print-cure-clean-dry (PCWD) process that uses industrial-grade piezoelectric inkjet printing followed by selective UV curing to achieve precise QD placement and prevent color bleeding.

In this study, Applied Materials demonstrated a prototype of a 1.37-inch smart watch display built using UV Micro LEDs combined with RGB quantum dot technology, achieving a pixel density of 318 PPI, brightness and high contrast of more than 3,000 nits. The display covers more than 90% of the DCI-P3 color gamut, which can be increased to 99% by enhanced pixel isolation.

Photo source: Applied Materials Company

In addition, compared to GaN-based Micro LED, OLED and LCD displays, quantum dot color conversion Micro LED displays exhibit higher uniformity of angular emission.

Applied Materials said that although the Micro LED full-color technology has made some progress, it is still not mature. In the future, improving LED efficiency at low current densities, solving the problem of carrier loss on Micro LED sidewalls, and ensuring the stability of quantum dots are the keys to the further development of this technology. Packaging technology and enhanced quantum dot synthesis are crucial to mitigate degradation and achieve long-term stable applications.