There are many advantages of LEDs in energy and environmental conservation, but their short life in many outdoor applications prompt a necessity to have a detailed understanding of their degradations to prolong their lifetime, which can also conserve LED material and even expand their applications. Using ab initio density functional theory formulation, we identify the detail paths of the LED degradation in outdoor applications. We discovered that the main stressors are humidity and the light that is emitted from the LED chip itself. This is rather ironical. A mathematical model is developed based on the ab initio study, and excellent experimental agreements are found. With this model, we can predict the situations where no and slow degradations can be achieved, and these are verified experimentally here. We can also predict quantitatively the time to a specific degradation severity. Quality index of the housing material for LEDs can also be determined.

中文翻译：

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可见光和湿度对大功率发光二极管封装材料稳定性的影响

LED在节能环保方面有诸多优势，但其在很多户外应用中寿命较短，因此需要详细了解其退化情况以延长其寿命，这也可以节约LED材料，甚至扩大其应用范围。使用从头算密度泛函理论公式，我们确定了户外应用中 LED 退化的详细路径。我们发现主要的压力源是湿度和 LED 芯片本身发出的光。这是相当讽刺的。数学模型是基于ab initio开发的研究，并发现了极好的实验协议。使用这个模型，我们可以预测可以实现无退化和缓慢退化的情况，这些都在这里通过实验验证。我们还可以定量预测达到特定退化严重程度的时间。也可以确定 LED 外壳材料的质量指标。