Hands holding glowing 3D-printed objects.

These 3D-printed objects are luminous under ultraviolet light thanks to crystals of fluorescent dye. Credit: Amar Flood

Materials science

Ultra-fluorescent dyes give objects an eye-popping glow

Crystals of physically distanced dye molecules fluoresce brilliantly in a rainbow of colours.

Scientists have combined new fluorescent dyes with plastic to create some of the most brightly glowing objects ever made.

Most fluorescent molecules lose their glow when they are packed closely together, whether in a concentrated solution or a solid light-emitting display. This limits their brightness and versatility.

Bo Laursen at the University of Copenhagen, Amar Flood at Indiana University in Bloomington and their colleagues deployed flat, star-shaped molecules to address this flaw. The team’s method applies to tens of thousands of dyes that have a large fluorescent component and a small non-fluorescent component.

The star-shaped molecules trap the non-fluorescent component inside molecular ‘sandwiches’, forming discs that are similar to the fluorescent component in shape and size. These discs and the fluorescent components stack themselves alternately into a crystalline 3D lattice, isolating the fluorescent components from each other.

The researchers successfully transformed representatives of five major classes of fluorescent dye into crystals. They blended the crystals into plastic materials, producing films and 3D-printed shapes that glowed red, blue or green.