The Ministry of Education and the National Research Foundation (NRF) announced on Sept. 22 that a research team led by Joo Byung-kwon and Park Young-wook, professors at the School of Electrical Engineering of Korea University, has successfully developed nanoscale auxiliary electrodes that can deliver high electrical and optical performance. These auxiliary electrodes are used to compensate for the low conductivity of transparent electrodes utilized for a variety of displays and electric lighting.
In the past, large-scale transparent electrodes had poor light-emitting properties owing to the limits of conductivity. To address the problem, highly-conductible metal auxiliary electrodes were utilized. However, the area where light is emitted was reduced due to the opaque nature of metals.
With a method using the interference phenomenon of laser beams to form a nanostructure, the research team was able to solve the problem by developing nano-sized transparent auxiliary electrodes, which were reduced in size hundreds of times.
When these auxiliary electrodes were used in organic light-emitting diodes (OLEDs), the overall sheet resistance was decreased by half compared to the case where only transparent electrodes were used. Their light extraction efficiency was improved by 20 percent.
The team explained that the aluminum auxiliary electrodes show 70 percent permeability in the visible light region, which does not hurt aesthetics in the design of displays or lighting.
The research findings were first published online on Aug. 21 by Advanced Functional Materials, a bimonthly scientific journal published by Wiley-VCH. This study is going to be featured as the cover article in the upcoming issue.