Korea University Creates Fade-Proof Color Using Gold Nanoparticles

A research team led by Professor Lee Seung-woo of Korea University announced on the 5th that it has developed a nanopigment that produces fade-proof color. The pigment is a 'structural color nanopigment' that achieves vivid color without dyes by coating gold nanoparticles (extremely small gold particles) with selenium. Structural color, as seen in butterfly wings and peacock feathers, arises when a material's fine structure reflects light, and it does not fade even after prolonged exposure to light. However, existing structural color pigments were made from a single material and responded simultaneously to light across multiple wavelengths, making it difficult to render a desired color vividly.

The research team changed the very way the particles respond to light by composing the core and the shell of each particle from different materials. They designed the gold core and the surrounding selenium to each react to light and interfere with one another. By harnessing so-called Fano interference, the response became stronger or weaker at specific wavelengths, resulting in higher color purity and a wider range of expressible colors than single-component particles. The difference is also confirmed numerically. In terms of the quality factor, which measures how selectively a particle responds to a specific wavelength, conventional gold nanoparticles generally score below 10, while particles combining gold and selenium reached about 15.

Durability test results were also released. From November 2025 to July 2026, the team stored a nanoparticle dispersion liquid, a dried painting, and an ultraviolet-cured film indoors, and no noticeable color change was observed in any of the three samples. The film, after additionally undergoing UV irradiation and heating and freezing tests, showed optical properties nearly identical to those measured before the tests.