Phase-Selective Distribution of Eu2+ and Eu3+ in Oxide and Fluoride Crystals in Glass-Ceramics for Warm White-Light-Emitting Diodes
Phase-Selective Distribution of Eu2+ and Eu3+ in Oxide and Fluoride Crystals in Glass-Ceramics for Warm White-Light-Emitting Diodes
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DOI：
10.1021/acsaelm.9b00129
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发表时间：
2019-06-01
影响因子：
4.7
通讯作者：
Tanaka, Katsuhisa
中科院分区：
文献类型：
--
作者：
Gao, Yuan;Murai, Shunsuke;Tanaka, Katsuhisa
大功率白光发光二极管（WLED）包括无粘结剂的散装荧光粉和紫外（UV）LED芯片作为下一代照明光源进行了深入的研究。主要的挑战是在每个合适的晶相中有效管理不同的颜色成分，同时在近紫外激发下最大限度地提高其光学性能。在这方面，我们开发了含有Na5Gd9F32和NaAlSiO4的玻璃陶瓷，其中Eu3+和Eu2+的相选择性分布导致具有低相关色温（CCT）（< 3000 K）、高显色指数（Ra > 70）和有希望的热稳定性的暖白光发射。所得到的复合材料具有宽带光致发光（PL）的蓝绿色（NaAlSiO4：Eu2+）和红色（Na5Gd9F32：Eu3+）光谱区域附近。到573 K，PL强度保持在室温（RT）的50%以上。内部PL量子产率估计为35%。此外，在573 K下进行热老化测试1000 h，之后样品在RT下表现出初始PL强度的70.7%，并且在暖白色范围的色坐标中显示出稳定性。这项研究，这表现出潜在的实际应用，提供了一种策略，用于生成一个温暖的白光颜色与Eu2+和Eu3+在氧化物和氟化物相结合的紫外LED。
High-power white-light-emitting diodes (WLEDs) comprising binderless bulk phosphors and ultraviolet (UV) LED chips as next-generation illumination sources were intensively studied. The main challenge is the effective management of different color components in each suitable crystal phase while maximizing their optical properties with near-UV excitation. In this regard, we developed glass-ceramics that contain Na5Gd9F32 and NaAlSiO4, in which the phase-selective distribution of Eu3+ and Eu2+ results in warm white-light emission with a low correlated color temperature (CCT) (< 3000 K), high color rendering index (Ra > 70), and promising thermal stability. The obtained composite exhibits broadband photoluminescence (PL) around the blue-green (NaAlSiO4:Eu2+) and red (Na5Gd9F32:Eu3+) spectral regions. Up to 573 K, the PL intensity remains above 50% of that at room temperature (RT). The internal PL quantum yield was estimated as 35%. Further, a thermal-aging test was conducted for 1000 h at 573 K, after which the sample exhibited 70.7% of the initial PL intensity at RT and showed stability in the chromaticity coordinate for a warm white range. This study, which exhibits potential for practical applications, provides a strategy for the generation of a warm white-light color with Eu2+ and Eu3+ in oxide and fluoride phases in combination with UV LEDs.