Professor Soo-Seok Choi's team—EE doctoral students Seung-Min Nam (first author), Won-Tae Jeong and Jun-Hyuk Shin—developed the first optical nanodevice that freely tunes color toward either shorter or longer wavelengths, overcoming previous limitations.
Using a dielectric elastomer actuator with flexible, stretchable chiral liquid crystal elastomers (CLCEs) exhibiting structural color, they freely lengthened or shortened nanoscale dimensions and tuned structural-color wavelength and position in either direction. The study was published online in Nature Publishing Group's Light: Science & Applications (LSA; IF 19.4, JCI 98.74%, top 1.26%), one of the leading optics journals.
Color-wavelength tuning is essential across optical and electronic industries, including displays, semiconductor image sensors and biodevices. Conventional devices are generally constrained to selected colors and wavelengths by their designs. Most electronics produce color indirectly by mixing red, green and blue dyes or emitters, limiting direct wavelength expression and thus performance and applications.
Structural-color technology has recently gained strong interest because nanostructures hundreds of nanometers long—comparable to optical wavelengths—directly produce characteristic colors. Nanoscale interactions between structure and light allow expression and control without dyes or emitters. Leading research therefore focuses on changing nanostructure dimensions to tune multiple colors within one device and adjust its electromagnetic response range.
Previously, tuning was generally possible in only one direction, from longer structures to shorter ones and thus from longer to shorter wavelengths, with large adjustment ranges required. The team electrically controlled flexible dielectric elastomers to freely lengthen or shorten the light-responsive dimensions of CLCEs, greatly expanding the freedom of tunable wavelength control.
Beyond displaying structural color, the work could affect displays, semiconductors, electromagnetic-wave control, encrypted codes, biomimicry and wearables, wherever light, color and wavelength must be controlled under different conditions. It also advances precise control of structures hundreds of nanometers long, adjusting them by a few nanometers into varied configurations. LSA is expected to highlight its technical significance and industrial impact. The research was supported by the Samsung Science & Technology Foundation and the Korea Evaluation Institute of Industrial Technology's display innovation process program.