Scientists want to find ways to improve on the quality of light that light-emitting diodes (LEDs) produce, to reduce their cost, and to make them environmentally friendlier. A team including Zhichao Hu and Jing Li of Rutgers University has made progress on those goals in its design of a new white LED. The researchers started by developing a family of tetraphenylethylene-based chromophores that luminesce at different wavelengths. They then linked chromophores together with zinc ions to form a metal-organic framework (MOF) phosphor material. The Rutgers researchers can make any color LED they want by coating different colored LEDs with the various phosphors. The phosphor is excited by light produced by the underlying LED, and the mixture of the emissions from the LED and phosphor produce the desired color of light. To make a white LED, they coated a blue LED with a MOF-based yellow phosphor made using a chromophore named H4tcbpe. The new material has a performance level approaching that of the best commercially available phosphors, Hu said. In addition, it doesn’t require an increasingly expensive rare-earth metal typically used in LED phosphors and avoids toxic cadmium selenide used in quantum-dot-based LEDs.