loaction
연구성과
SNU Professor Yongtaek Hong's Team Steps Closer to the Core of Flexible Display Development
-
작성자
관리자
-
등록일
2020.10.28.
-
조회수
757
SNU Professor Yongtaek Hong's Team Steps Closer to the Core of Flexible Display Development
- Development of transparent electrode printing technology and wrinkle structure luminous element quality improvement technology
- Expected to be highly utilized for body-attached wearable technology in the future.
▲ (From left) Professor Yongtaek Hong, Researchers Jongjang Park, Geonhee Kim and Sujin Jeong
- Expected to be highly utilized for body-attached wearable technology in the future.
▲ (From left) Professor Yongtaek Hong, Researchers Jongjang Park, Geonhee Kim and Sujin Jeong
A research team within Korea developed a printable transparent electrode patterning technology that can be applied to next-generation flexible displays as well as utilize it to improve the quality of flexible organic light emitting devices based on wrinkled structures.
SNU College of Engineering (Dean Kookheon Char) announced on September 28 that a research team led by Professor Yongtaek Hong of the Department of Electrical and Computer Engineering (Researchers Jongjang Park, Geonhee Kim and Sujin Jeong) has developed two key technologies for the implementation of flexible luminous devices based on the printing process.
Silver nanowires, which are spotlighted as next-generation transparent electrode materials for flexible display applications, have previously had technical barriers in terms of its complexity, high unit price, and low adhesion during the process of forming fine patterns. In particular, the technology of forming silver nanowire transparent electrodes directly above the organic layer, which is easily degraded in the solution process, was considered to be a challenge.
In response, the researchers greatly improved the process of forming transparent conductive organic electrodes based on PEDOT:PSS (conductive polymer). By utilizing PEDOT:PSS electrode template which was patterned with inkjet printing, it was possible to develop a technology that transmits silver nanowire electrode patterns to various surfaces such as organic matter, plastic, and glass.
Depending on the width of printed templates, it is possible to form nanowire micro-patterns up to several micrometers wide and by adjusting the amount of transferred silver nanowires, the transparency of electrodes can be adjusted simultaneously.
In addition, nanowires were transferred to the PEDOT:PSS electrodes, resulting in a significant improvement in adhesion to various surfaces. Through this technology, the researchers produced transparent touchscreen panels, flexible inorganic light emitting device arrays, and organic light emitting diodes based on all solution processes, showing its dynamic applicability.
Further, many studies are being conducted on technologies that do not degrade the luminous properties even if the physical wrinkle structure is added within the luminous area to develop flexible organic light emitting diodes. In particular, after making luminous elements on several micrometer thick films such as polyimide varnish, many techniques are applied to form wrinkle structures by transcending over flexible substrates.
In this case, the mechanical stretch properties are improved due to the macro-wrinkle structure the size of several hundred micrometers, but at the same time it can cause distortion and deterioration of quality. In response, the research team developed an inkjet printing process technology that directly forms transparent conductive PEDOT:PSS organic electrodes on flexible substrates and reduces the wrinkle structure to less than 20 micrometers - which is almost unrecognizable to humans - to maintain photovoltaic and mechanical properties of the device without compromising image quality. Organic light emitting diodes of micro wrinkle structure operated without any change in performance even under 120% expansion.
Because the technology developed by the research team is formed by electrode patterns through the inkjet printing method, compared to the existing method, the speed for processing is faster, the cost is reduced and the advantage of conductive organic electrodes is expanded on while silver nanowires help overcome its limitations.
Professor Yongtaek Hong says, "Through the convergence of the two research results, we are currently researching technologies that implement organic light emitting diodes for high-performance and high-resolution flexible display applications using low-cost electrode pattern methods, and we expect that flexible nanowire electrodes with various thicknesses and shapes will easily be formed into fine patterns by using the printing technology, which is also expected be highly utilized for body-attached wearable technologies in the future."
▲ The silver-nano-wire patterning process through inkjet and transfer printing combinations and illustration of electrodes pattered on various substrates (Right) Cover paper of the June issue of <Advanced Materials Technology>
▲ (Left) Illustration of pixel distortion and luminous array formation based on Wrinkle Structure Size in a wrinkle structure based flexible luminous device
(Right) Cover paper of the September issue of <Advanced Materials Technology>
담당부서대외협력실
전화번호880-9148