Systematic Approach in Designing Rare-Earth-Free Hybrid Semiconductor Phosphors for General Lighting Applications

As one of the most rapidly evolving branches of solid-state lighting technologies, light emitting diodes (LEDs) are gradually replacing conventional lighting sources due to their advantages in energy saving and environmental protection. At the present time, commercially available white light emitting diodes (WLEDs) are predominantly phosphor based (e.g., a yellow-emitting phosphor, such as cerium-doped yttrium aluminum garnet or (YAG):Ce3+, coupled with a blue-emitting InGaN/GaN diode), which rely heavily on rare-earth (RE) metals. To avoid potential supply risks of these elements, we have developed an inorganic–organic hybrid phosphor family based on I–VII binary semiconductors. The hybrid phosphor materials are totally free of rare-earth metals. They can be synthesized by a simple, low-cost solution process and are easily scalable. Their band gap and emission energy, intensity, and color can be systematically tuned by incorporating ligands with suitable electronic properties. High quantum efficiency is achieved for some of these compounds. Such features make this group of materials promising candidates as alternative phosphors for use in general lighting devices.