A team of HPSTAR (the Center for High Pressure Science and Technology Advanced Research) scientists, led by Drs. Takeshi Nakagawa and Yang Ding, has developed a single-component organic-molecular crystal that emits red, green and blue (RGB) light – the key color components for full-color displays. Published in Carbon, the research successfully realized distinct crystalline forms of coronene (C24H12) that produce stable RGB spectrum under uniform ambient conditions using a single excitation wavelength.
“We address a fundamental challenge in organic optoelectronic technology: Can RGB emission be generated from one organic material?” said Dr. Nakagawa. Typically, generation of RGB emission that covers wide wavelengths (blue: 450 nm, green: 500nm and red: 600nm) requires employing different materials for each color, or use multiple components for color tuning, or varying external conditions to induce color changes. Building on our previous high-pressure experiments, we used crystal engineering to control the crystal structure and crystal morphology of coronene to achieve RGB emission that only involves coronene, single-component, and under the same condition.
Caption: Photoluminescent micrographs of three different coronene single-crystals exhibiting red, green and blue (RGB) emission under UV-light at same ambient conditions. Schematic representation of key difference between single-crystals and mechanism responsible for emission color changes.
By combining various characterization techniques, the team revealed that the key mechanisms for color variation are the modulation of excited-state dynamics and the enhancement of intermolecular interactions within the crystal system.
"Our research uncovers unprecedented control over the luminescence properties of single-component organic single-crystals by altering their morphological dimensionality,” said Dr. Nakagawa. This work is expected to generate broad interest across various fields, as it holds a direct relevance to functional molecular materials, solid-state chemistry, and to the extended condensed matter scientific community.
