Keeping them distant for ultimate brightness

While strong absorption is best achieved with high activator concentrations, luminescence brightness typically suffers in that case due to energy migration and concentration quenching. The teams around Xia and Zhong have reported about an aphthitalite-type Eu-activated phosphate that breaks with this paradigm and enables the sustainment of high photoluminescence quantum yields (>40%) up to concentrations as high as 70 mol% Eu. Mixing of that phosphor with a low (0.8%) and high (70%) Eu fraction results in almost natural white light with excellent color rendition and correlated color temperature that could serve as a new instructive concept for next-generation phosphor-converted white LEDs.