An abundant copper compound could replace rare-earth metals in household LEDs, making them more environmentally friendly. Most commercially available white LEDS are phosphor-based but incorporate rare earth metals like cerium. Researchers from Rutgers University developed another approach to white LEDs based on I-VII binary semiconductors, in particular copper iodide. The hybrid phosphor materials are free of rare-earth metals and can be synthesized by a low-cost, scalable solution process, the researchers said. Introduction of ligands allows the LEDs to be tuned to emit a warm white glow or other colors. The work was funded by the National Science Foundation and published in the Journal of the American Chemical Society (doi: 10.1021/ja507927a). For more information, visit www.rutgers.edu.