Dr. Ho Seong Jang and colleagues at the Extreme Materials Research Center at the Korea Institute of Science and Technology (KIST) have developed an upconversion nanoparticle technology that introduces a core@multi-shell nanostructure, a multilayer structure in which multiple layers of shells surround a central core particle, and enables high color purity RGB light emission from a single nanoparticle by adjusting the infrared wavelength.