Opt. Lett. 36, 2868–2870 (2011)
White-light-emitting diodes (white LEDs) are increasingly used for applications such as lighting. However, the phosphorescent materials used to convert the blue light of the LED into red light to achieve the LED's overall white-light emission contain rare-earth elements that are increasingly difficult to obtain on the world market. Hirokazu Masai and colleagues from Kyoto University have now developed a new material for use in white LEDs that contains no rare-earth elements. Instead of using energetic states in rare-earth elements, manganese offers an alternative for light conversion at similar wavelengths. And instead of using a crystalline phosphor as a matrix for the manganese cations, here the light conversion works best if a glass is used. This has the additional benefit that the emission of the red light occurs across a broader range of wavelengths, which enhances the overall light emission. Furthermore, with conversion efficiencies that match those of the rare-earth dopants presently in use, rare-earth-free white LEDs might soon be a reality.
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Heber, J. Not-so-rare LEDs. Nature Mater 10, 808 (2011). https://doi.org/10.1038/nmat3165