The Korea Electrotechnology Research Institute (KERI) has succeeded in elucidating the highly directional luminescence pattern observed in nanostructures, which is expected to lead to technological innovation in the field of ultra-high-resolution displays.

KERI announced on the 22nd that Dr. Pyo Jae-yeon's team has discovered the world's first luminescence pattern of a 3D-printed nanostructure, and that the related research results were published as a cover paper in the international academic journal ACS Nano.

In display devices, higher resolution means more pixels on one screen. As pixel density increases, images and photos are displayed more precisely and delicately.

Therefore, research is ongoing to make light-emitting elements smaller, from micrometers (one millionth of a meter) to nanometers (one billionth of a meter), in order to increase pixel density.

As light-emitting elements shrink to a few hundred nanometers in size, unusual changes occur in the interaction between light and matter, resulting in a marked departure from the typical, consistent light-emitting pattern. Understanding these unique luminescence patterns is essential for practical applications of nano-luminescent devices.

Accordingly, the KERI research team, which has been studying the display field for several years using nanophotonic 3D printing technology, succeeded in elucidating the highly directional light emission pattern observed in nano structures based on the research capabilities accumulated over the years.

In general, it is difficult to uniformly produce luminescent materials in the desired location and size using conventional chemical or physical deposition methods.

On the other hand, KERI 3D printing technology can limit the diameter of the structure by the diameter of the printing nozzle, so it can reliably produce luminescent materials in the desired size (1/10,000 to 1/10 million meter in diameter) over a wide range at the desired location.

Dr. Pyo Jae-yeon's team experimentally measured the luminescence patterns using specimens precisely implemented from nanometers to micrometers using 3D printing technology, and also performed electromagnetic wave simulations for in-depth analysis and cross-validation.

As a result, it was discovered that when the size of the light-emitting element is made very small, such as 300 nanometers in diameter, internal reflection of light disappears due to spatial limitations, so it propagates only in one straight direction, and therefore exhibits a highly directional light emission pattern when light is emitted. Basically, light propagates through various paths inside a structure, and a wide light emission pattern is exhibited due to the overlapping of these, but in the nanowire structure, only a single straight path exists, exhibiting a highly directional light emission pattern.

These characteristics can be used to significantly improve the performance of displays, optical storage media, and encryption equipment. When structures with existing wide light-emitting patterns are brought close together, they overlap or blur each other, causing 'optical crosstalk'. On the other hand, the KERI research team experimentally suggested that nanowires with a highly directional emission pattern can be utilized to implement high-performance devices because they enable clear distinction between pixels even when gathered at a high density and there is no distortion in information interpretation.

The results of this study were recently published as a cover paper in 'ACS Nano', a top-tier SCI academic journal in the field of nanoscience published by the American Chemical Society, in recognition of its excellence. The 'JCR Impact Factor', which evaluates the influence of academic journals, is 15.8, which puts it in the top 5.9% in the field.

Dr. Pyo Jae-yeon said, “Photophysics research in the nano-domain is difficult and time-consuming to produce specimens, but we have been able to elucidate the luminescence aspects of nanostructures for the first time using a simple and flexible 3D printing platform.” He added, “The results of this study will greatly contribute to enhancing technological competitiveness in advanced displays, which are national strategic technologies, and quantum fields.”

The research team expects that this research will attract attention in the fields of virtual reality (AR, VR), beam projectors, optical storage media, optical integrated circuits, encryption technology, and security printing where ultra-small light-emitting devices can be utilized, and plans to apply and spread the results. In addition, the goal is to continue to elucidate various optical physics phenomena occurring in the nanometer range by utilizing 3D printing technology that can freely create desired structures.

Meanwhile, KERI is a government-funded research institute under the National Research Council of Science and Technology of the Ministry of Science and ICT. Dr. Pyo Jae-yeon is also working as an associate professor at the University of Science and Technology (UST).