New Transparent Electrodes Foldable Over 1000 Times like Paper

Study to Help Quicken Commercialization of Flexible Electronics

                     

A Korean research team has developed flexible and transparent electrodes that satisfy the standard specifications, namely a transmittance of 90% or higher in the visible range and a sheet resistance of 10 Ω/sq or lower. Their research is expected to help pave the way toward commercialization of flexible electronics.

The research was led by corresponding author Prof. Kwanghee Lee of GIST School of Materials Science and Engineering and by co-first authors Dr. Hongkyu Kang of the Research Institute for Solar and Sustainable Energies (RISE) and Ms. Suhyun Jung, a doctoral student at GIST School of Materials Science and Engineering. This work was supported by the National Research Foundation of Korea grant, funded by the Ministry of Science, ICT and Future Planning, and by the Core Technology Development Program for Next-generation Solar Cells of RISE, GIST. The result was published online on March 19, 2015 in Nature Communications (Title: Polymer-metal hybrid transparent electrodes for flexible electronics).

Flexible and transparent electrodes are considered a key component to realize future ubiquitous electronic devices, such as flexible displays and wearable electronics. Despite recent research efforts to develop new electrodes, further enhancement in the performance of the transparent electrodes fabricated on flexible plastic substrates is still required to meet the standard specifications of a high transmittance in the visible range and a low sheet resistance.

The research team developed an innovative method to overcome metal island growth originating from random migration and aggregation of thermally evaporated metal droplets on substrate surface. By introducing an amine-containing polyelectrolyte as a metal nucleation-inducing seed layer on the top of the substrate, the research team created uniform, strong metallization nuclei on plastic substrates in which the nucleation centers are densely distributed over atomic-scale distances. As a result, the research team successfully fabricated extremely flexible, conductive and transparent polymer-metal hybrid electrodes with unprecedented performances, including a high visible-range transmittance of over 95%, a low sheet resistance of lower than 10 Ω/sq and an excellent mechanical stability with a nearly constant resistance after continuous bending cycles.

Prof. Kwanghee Lee said, “Our new approach is expected to help realize the large-area and mass production of the flexible and transparent electrodes because it requires simple and low-cost manufacturing processes. In addition, we hopefully believe the results will pave the way to commercialization of ubiquitous optoelectronic applications such as flexible and wearable electronics.”