Development of the World's Most Efficient Deep Blue OLED Device

KAIST-Gyeongsang National University Research Team

A domestic research team has developed a deep blue organic light-emitting diode (OLED) with world-class high efficiency.

Schematic of Emissive Molecule Design Concept for High-Efficiency Deep Blue OLED Device Implementation and Example of Device Operation. Image Source: Provided by KAIST

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 3rd that Professor Seunghyup Yoo’s research team from the Department of Electrical Engineering collaborated with Professor Yoonhee Kim’s research team from the Department of Chemistry at Gyeongsang National University to achieve this result.

OLEDs are light-emitting devices used in advanced display technology, offering several unique advantages such as clear image quality, thin thickness, and the ability to manufacture flexible devices essential for foldable or rollable displays. In these applications, it is very important to secure sufficient efficiency and lifespan of the red, green, and blue light sources that make up the three primary colors of light, while simultaneously achieving high color purity of the three primary colors. However, technology that meets all three requirements simultaneously in blue OLED devices is considered a representative challenge.

The research results were published online on the 31st of last month in the international academic journal Science Advances.

The research team focused on the design of boron-based delayed fluorescence materials, a next-generation emitter recently attracting attention, to realize deep blue OLED devices. These materials have the advantage of excellent color purity but have a limitation in that deep blue emission is only possible at low concentrations due to strong intermolecular interactions caused by their flat molecular structure. Increasing the concentration of the emitting molecules to secure sufficient efficiency in OLED devices poses a difficult problem, as it prevents fully utilizing the color purity advantage of the emitter itself.

The research team simplified the synthesis process and improved the low yield compared to previously known boron-based materials, which are known to be very difficult to synthesize. From a molecular dynamics perspective, they successfully identified a molecular structure that can suppress intermolecular interactions. By implementing this through molecular design, they solved the challenge of color purity and efficiency degradation. The team especially established a comprehensive and analytical methodology to theoretically predict the structure that can achieve maximum efficiency. By applying the designed high-efficiency organic emitting material to the device structure, they succeeded in realizing a deep blue OLED with a maximum external quantum efficiency of over 35%. This is a world-class result for the efficiency of deep blue OLED unit devices at the corresponding wavelength.

Professor Yoo said, "Securing high-efficiency deep blue OLED technology is one of the essential tasks to complete OLED displays as the ultimate technology," adding, "This research is a good example demonstrating the importance of systematic convergence research and collaboration between material and device groups in solving difficult challenges."

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