In general, lighting application, white light emitting diode (LED) usually exposed to an extreme operating temperature of above 90°C. It is well-known that luminous efficacy and spectral characteristic of white LED are dependent on the temperature, causing thermal effects on luminous efficacy and color shift of white LED become a critical application checkpoint to be addressed by white LED manufactures. Thus, the purpose of this paper is to minimize the thermal stability issue affecting white LED luminescence during operation by introducing phosphor sedimentation process.,The LED samples were assembled and sent for centrifugation with 0, 5 and 10 revolutions per second (rps), respectively, during phosphor sedimentation process. Luminescence properties of these LED samples were then characterized at a varying temperature to investigate the effect of phosphor sedimentation on the luminescence stability of LED samples. The LED samples were also cross-sectioned and analyzed to understand the phosphor sedimentation mechanism. Computational fluid dynamics (CFD) was applied to study the temperature distribution of the non-phosphor sediment (NPS) and phosphor sediment (PS) LED during operation to validate the hypotheses based on experimental data.,Experimental results show that the luminous intensity of PS LED samples degrades less significant at high temperature. The experimental results also show that the color coordinate for PS LED samples is more stable and is less blue-shifted than NPS LED samples as the temperature increased. These are because the heat generated by phosphor particles during operation can be dissipated effectively throughout a high thermal conductivity substrate after phosphor sedimentation. Thus, the phosphor temperature of PS LED is lower than NPS LED during operation as validated with the thermal simulation.,The study of this paper is applicable as a reference for industries who intend to resolve the thermal stability of white LED during operation. The luminescence properties changes as a function of the temperature study in this paper can be used to predict the application performances of white LED accurately. Apart from that, the analysis method of temperature distribution using CFD simulations can be extended by other CFD users in the future.,Implementation of phosphor sedimentation to reduce thermal instability issue of white LED has yet to be reported on previous studies. Most literature just studied the thermal instability issue of either assembled LED or raw material, without suggesting any solution to tackle the issue.

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实施磷光体沉淀以减少影响白光 LED 发光的热不稳定性问题

一般而言，照明应用中，白光发光二极管 (LED) 通常暴露于 90°C 以上的极端工作温度。众所周知，白光 LED 的光效和光谱特性取决于温度，导致白光 LED 光效和色偏的热效应成为白光 LED 制造商需要解决的关键应用检查点。因此，本文的目的是通过引入磷光体沉降过程来最大限度地减少运行过程中影响白光 LED 发光的热稳定性问题。,LED 样品被组装并分别以 0、5 和 10 转/秒 (rps) 进行离心。 , 在磷沉降过程中。然后在不同温度下表征这些 LED 样品的发光特性，以研究磷光体沉积对 LED 样品发光稳定性的影响。还对 LED 样品进行了横截面和分析，以了解荧光粉的沉积机制。应用计算流体动力学 (CFD) 研究非磷沉积 (NPS) 和磷沉积 (PS) LED 在运行期间的温度分布，以验证基于实验数据的假设。, 实验结果表明，PS 的发光强度LED 样品在高温下劣化不太明显。实验结果还表明，随着温度的升高，PS LED 样品的色坐标更稳定，并且比 NPS LED 样品的蓝移更少。这是因为在荧光粉沉积之后，荧光粉颗粒在操作过程中产生的热量可以在整个高热导率基板上有效消散。因此,经热模拟验证,PS LED在运行过程中的荧光粉温度低于NPS LED。,本文研究可作为解决白光LED运行过程热稳定性问题的参考。本文研究的发光特性随温度变化的变化可用于准确预测白光 LED 的应用性能。除此之外，未来其他CFD用户可以扩展使用CFD模拟的温度分布分析方法。以前的研究尚未报告实施磷光体沉积以减少白光 LED 的热不稳定性问题。大多数文献只研究了组装 LED 或原材料的热不稳定性问题，没有提出解决该问题的任何解决方案。