Luminescent Glass Ceramics for White LED Applications

用于白光 LED 应用的发光玻璃陶瓷

• 批准号: 323730539
• 负责人: Professor Dr. Stefan Schweizer
• 金额: --
• 依托单位: Fachbereich Elektrische Energietechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/323730539?language=en
• 关键词: Luminescent; Glass; Ceramics; White; LED

White LEDs mostly consist of blue emitting LED chips combined with a yellow-emitting phosphor. Due to the lack of red spectral component, the color impression of such LEDs is often shifted slightly to the cold blue spectral range. The limitation of the phosphor is its degradation when exposed to the high temperatures of the LED chips. The use of luminescent glasses and glass ceramics as a combination of phosphor and encapsulant are more resistant to high temperatures than conventional polymer-based encapsulation. Through selective doping with elements from the group of rare-earth metals, the emission and subsequently the color impression can be adjusted. Owing to their high mechanical, chemical and thermal stability, borate glasses are to be used as matrix material.Within the framework of this project, new luminescent glass ceramics are developed and optimized in terms of their optical properties. Crystallites were obtained through the thermal treatment of pre-synthesized luminescent glasses. By scattering and multiple reflections on the crystallites, the optical path length in these systems can be significantly increased, so that the light output at the same optical excitation power increases. The glass ceramics under examination consist of lithium, sodium or barium borate glasses with different levels of doping of different rare-earth metal ions. The rare-earths are used as optical activators. Upon excitation in the ultraviolet or blue spectral range, they show a strong emission in the visible spectrum.

白色LED主要由发射蓝光的LED芯片和发射黄光的磷光体组成。由于缺乏红色光谱分量，这种LED的颜色印象通常稍微偏移到冷蓝色光谱范围。磷光体的局限性在于当暴露于LED芯片的高温时其降解。使用发光玻璃和玻璃陶瓷作为磷光体和密封剂的组合比传统的基于聚合物的密封剂更耐高温。通过选择性地掺杂稀土金属元素，可以调节发射和随后的颜色印象。由于硼酸盐玻璃具有较高的机械、化学和热稳定性，因此将其用作基质材料。在本项目的框架内，开发并优化了新型发光玻璃陶瓷的光学性能。通过热处理预合成的发光玻璃获得微晶。通过在微晶上的散射和多次反射，这些系统中的光程长度可以显著增加，使得在相同的光激发功率下的光输出增加。所研究的玻璃陶瓷由锂、钠或钡硼酸盐玻璃组成，具有不同稀土金属离子的不同掺杂水平。稀土被用作光学活化剂。在紫外或蓝色光谱范围内激发时，它们在可见光谱中显示出强烈的发射。