韩国POSTECH教授披露可调谐“real full color”纳米结构显示技术进展

A technology capable of overcoming the limits of the RGB method, long the standard for color reproduction in televisions and smartphones, has been developed in South Korea. Instead of mixing red, green and blue light to create colors, the approach tunes nanostructures to directly generate and freely alter the desired color and the wavelength of light itself. The technology is expected to serve as a core foundational technology for next-generation optoelectronics, including augmented reality, holograms, optical semiconductors and image sensors, in addition to displays.
Choi Soo-seok, a professor of electrical engineering at POSTECH who was selected as the September winner of the Korea Science and Technology Award — hosted by the Ministry of Science and ICT and co-organized by the National Research Foundation of Korea and Seoul Economic Daily — said on the 2nd that the "real full color" technology is "expanding displays beyond devices that are simply viewed into technologies that can be touched, heard and interacted with." Choi added, "Over the next five to 10 years, what matters will be not just proposing new display technologies but creating clear user value and industrial benefits."
Choi moved beyond the display design premise taken for granted for decades — that colors are created by mixing three fixed RGB primaries — and presented a new possibility of directly generating and controlling the color and wavelength of light. The RGB method has served as the industry standard for decades because it can stably reproduce countless colors from combinations of just three primaries. But because it relies on combining multiple colors, it carried a fundamental limitation: reproducing the high-purity colors found in nature becomes difficult as materials, pixel design and manufacturing processes grow more complex.
Choi and the research team found their solution in butterflies and chameleons. Rather than mixing pigments, butterflies and chameleons produce vivid "structural colors" by using regular microstructures measured in nanometers that selectively reflect light of specific wavelengths. When the spacing of the structure changes, the wavelength of reflected light changes, and the color visible to the eye changes as a result. Artificially replicating such intricate nanostructures found in nature, however, requires complex nanofabrication processes.
To address this, the team used "chiral nanostructures," in which molecules spontaneously arrange themselves in a helical pattern. In effect, the team reproduced through chiral nanostructures the principle by which structural colors in nature arise from microstructures. As a result, the desired color and wavelength can be directly created and altered by adjusting the periodicity of the molecular structure, without complex nanofabrication. A signature achievement of the technology is "photonic e-skin," which mimics chameleon skin. When the material is stretched, the spacing of the nanostructure changes, and the wavelength and color of reflected light change accordingly. The team also identified the relationship between the degree of stretching and the color wavelength, making the material more than one that simply changes color — it allows the extent of an object's deformation to be read and analyzed directly through color.
The team also developed a "tunable color filter" that can select and display a desired color using a voltage of only about 2 volts. Conventional displays require a separate filter for each color, such as red, green and blue, but this technology produces multiple colors from a single chiral nanostructure and changes color by adjusting the voltage. More recently, the team applied the same principle to lasers, allowing the color of light emitted from a single laser to be freely varied across the visible spectrum from red to violet. Because it can reproduce far higher color purity than typical organic light-emitting diode or quantum dot technologies, it is expected to be used in next-generation optical technologies that require sharp, precise light, such as augmented reality and holograms.
The research grew out of experience and questions Choi accumulated over a long career in industry. During 19 years at LG Display, Choi encountered firsthand the process complexity, optical loss and color-purity limits of RGB color mixing. After moving to POSTECH in 2019, Choi began full-scale research on next-generation displays based on chiral nanostructures to overcome those limits. "We have researched stretchable displays with LG Display for a long time, and we have also been working with Samsung Electronics for several years on research extending optical technologies into semiconductors and image sensors," Choi said. "Connecting the practical perspective of industry with the university's freedom to pursue fundamental questions is an important direction for our current research."
Choi is now pursuing research on "optical encryption," which goes beyond reproducing color to embedding information in light itself. The technology assigns different color, wavelength and polarization information to each pixel and uses electrical stimuli or material deformation as decryption conditions. By layering multiple levels of information onto a single image and allowing it to be read only under specific conditions, the approach could be applied to anti-counterfeiting and authentication, high-density optical data storage and optical information processing.
The technology is expected to grow more important in the era of artificial intelligence. "Most encryption technologies in use today are electrical and digital, but achieving higher security also requires an approach that draws on physical information channels different from existing methods," Choi said. "Light can carry not only various colors and intensities but also wavelength, polarization and spatial patterns at the same time, which makes it a very interesting medium for encryption."