White Light-Emitting Fluorophore Has Solid-State Applications

David L. Shenkenberg

White light emitted from displays is traditionally made by mixing red, green and blue light, but a novel class of fluorophores that radiate white light could one day provide another source, especially via LEDs.

Robert M. Strongin and colleagues at Louisiana State University in Baton Rouge synthesized the fluorophores and studied their spectral properties. They examined them with a Varian Inc. UV-VIS spectrometer and a Horiba Jobin Yvon fluorescence spectrometer.

A representative fluorophore exhibited pH sensitivity and, in buffer, was excitable from 260 to 600 nm, a range of wavelengths that includes the emissions of helium-neon, argon-ion and helium-cadmium lasers. In neutral buffer solutions, it emitted white light composed of 620-, 540- and 390-nm spectral bands.

Another fluorophore radiated light closer to pure white. This light consisted of two bands that spanned ∼330 to 450 nm and 520 to 620 nm. It may be particularly useful for constructing white LEDs because most of them use two-band white light.

The fluorophores are pH-sensitive, which could be a challenge for solid-state applications. Nevertheless, Strongin believes that incorporating them into solid-state devices is only contingent upon finding the right matrix or the right chemicals that will allow electricity to be conducted through the fluorophores and that will stabilize the pH.

Journal of the American Chemical Society, Nov. 1, 2006, pp. 14081-14092.