Jewel-toned organic phosphorescent crystals: A new class of light-emitting material

Feb. 13, 2011

Jewel-toned organic phosphorescent crystals: A new class of light-emitting material

ANN ARBOR, Mich.—Pure organic compounds that glow in jewel tones could potentially lead to cheaper, more efficient and flexible display screens, among other applications.

University of Michigan researcher Jinsang Kim and his colleagues have developed a new class of material that shines with phosphorescence—a property that has previously been seen only in non-organic compounds or organometallics.

Kim and his colleagues made metal-free organic crystals that are white in visible light and radiate blue, green, yellow and orange when triggered by ultraviolet light. By changing the materials' chemical composition, the researchers can make them emit different colors.

The new luminous materials, or phosphors, could improve upon current organic light-emitting diodes (OLEDs) and solid-state lighting. Bright, low-power OLEDs are used in some small screens on cell phones or cameras. At this time, they aren't practical for use in larger displays because of material costs and manufacturing issues.

The OLEDs of today aren't 100 percent organic, or made of carbon compounds. The organic materials used in them must be spiked with metal to get them to glow.

"Purely organic materials haven't been able to generate meaningful phosphorescence emissions. We believe this is the first example of an organic that can compete with an organometallic in terms of brightness and color tuning capability," said Kim, an associate professor of materials science and engineering, chemical engineering, macromolecular science and engineering, and biomedical engineering.

This work is newly published online in Nature Chemistry.

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