Particle swarm optimization-assisted discovery of a novel oxynitride phosphor for use in light emitting diodes and its structural determination

摘要

Either pure nitrides or oxynitrides have attracted a great deal of attention as potential phosphors for use in light emitting diode (LED) applications, since they proven to be superior to traditional oxide and sulfide based phosphors in terms of both performance and stability. In this regard, the discovery of novel oxynitride phosphors has been a significant issue in the LED industry. To overcome conventional trial-error-based discovery, we introduced particle swarm optimization in search for novel phosphors. We finally discovered a novel oxynitride phosphor in the SrO-BaO-CaO-Si_3N_4 quaternary composition search space, and identified it as a monoclinic structure in the Cm space group. The exact structure and stoichiometry is now being determined, using direct method and ensuing Rietvelt refinement based on synchrotron X-ray diffraction data. The discovered phosphor showed broad band type yellow-red light emission at UV and blue light excitations, which could be a candidate for use in LED applications.