University of Georgia researchers have fabricated an LED that emits warm white light using a single light emitting material (phosphor) with a single emitting center for illumination.

“Right now, white LEDs are mainly used in flashlights and in automotive lamps, but they give off a bluish, cool light that people tend to dislike, especially in indoor lighting,” says Zhengwei Pan, an associate professor in the department of physics in the UGA Franklin College of Arts and Sciences and in the College of Engineering. “Our material achieves a warm color temperature while at the same time giving highly accurate color rendition, which is something no single-phosphor-converted LED has ever been shown to do.”

Warm white light can commonly be achieved with a blue LED chip coated with light emitting materials, or phosphors, of different emitting colors to create what are called phosphor-based white LEDs, Pan said. Combining the source materials in an exact ratio can be difficult and costly, however, and the resulting color often varies because each of the source materials responds differently to temperature variations.

“The use of a single phosphor solves the problem of color stability because the color quality doesn’t change with increasing temperatures,” says Xufan Li, a doctoral student in the College of Engineering.

The results have been published in a scientific journal here.

Craig DiLouie

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