Understanding structure-property relations of solid-state lighting phosphors

Modern solid-state lighting systems consist of a blue InGaN LED source in conjunction with a yellow phosphor, called a phosphor-converted LED (pc-LED). The combination of blue and yellow light produces white light. These pc-LEDs are a promising way of creating efficient white light in systems that are long-lived, durable, and mercury-free. Efficient white LED lighting is often at odds, however, with the effective reproduction of the wide spectral gamut of sunlight i.e. a high color rendering index, CRI. The widely used and studied yellow phosphor, Y3Al5O12:Ce (YAG:Ce) is explored here using synchrotron X-ray diffraction as well as 27Al and 89Y NMR as well as neutron pair distribution function studies. Changes in the NMR spectra are monitored as a function of paramagnetic Ce3+ introduced into the YAG Y site. NMR results are combined with neutron pair distribution function data and synchrotron X-ray data to relate structure and composition to quantum efficiency and excitation/emission spectra of YAG.