主动制冷水滴凝结法微结构制备机理研究及其多基色LED封装混光应用

It is an inevitable trend for development of solid state lighting technology and industry to realize full spectrum and high light quality LED lighting by multiple color LED packaging. Encapsulation layer with microstructure has significant advantages in color mixing of multiple color LED packaging. This proposal studies the fabrication mechanism of microstructure by initiative cooling based water droplet condensing method, and meets the requirements of simple process, low-cost, and flexibly controlled morphology. The proposed works include: 1) Establishing numerical model coupling heat transfer and three phase flow and studying the flow behavior and the interaction mechanism of water droplet and polymer with the application of initiative cooling; 2) Constructing experiment setup and studying water droplet condensation process with the application of initiative cooling; 3) Fabricating microstructure on encapsulation layer and using for multiple color LED packaging, and measuring optical performance of the multiple color LED packaging modules. As such microstructure can not only realize the color mixing of photon with various wavelength by scattering, but also reduce the reflection loss at the interface, resulting in the improvement of light quality and light extraction efficiency. This proposal covers a typical fundamental problem abstracting from the processes and applications. By such a research, we hope to instruct and realize advanced microstructure fabrication process that can be used for multiple color LED packaging, and promote the LEDs indeed penetrating into the higher quality lighting market.

通过多基色LED封装合成白光，实现真正意义的全光谱高品质光源是半导体照明技术和产业发展的必然趋势。表面微结构胶体在实现多基色LED封装混光方面具有显著优势。本项目研究基于主动制冷的水滴凝结法微结构制备机理，满足工艺简单、低成本与形貌灵活可控需求。研究内容包括：1）建立耦合传热和三相流动的数值分析模型，研究主动制冷作用下水滴与胶体的相互作用机理；2）搭建实验平台，研究主动制冷作用下水滴在胶体表面的凝结规律；3）开展微结构制备实验并应用于多基色LED封装，并测试多基色LED封装模块光色性能。通过封装胶体表面微结构散射作用实现了不同能量光子的均匀混合并降低了界面全反射损耗，可有效提高LED器件的光色品质与出光效率。本课题是一个典型的从工艺和应用中提出的基础问题，期望研究结果能指导实现应用于多基色LED封装的先进微结构制备工艺，促进LED真正迈向高品质照明应用领域。

通过多基色LED封装合成白光，实现真正意义的全光谱高品质光源是半导体照明技术和产业发展的必然趋势。表面微结构胶体在实现多基色LED封装混光方面具有显著优势。本项目研究基于主动制冷的水滴凝结法微结构制备机理，满足工艺简单、低成本与形貌灵活可控需求。主要研究内容包括主动制冷作用下水滴与胶体作用机理及水滴凝结规律，在此基础上开展形貌可调控表面微结构制备实验，并研究表面微结在LED封装中的应用。取得如下的研究成果：（1）建立了水滴-胶体-空气三相流动模型，揭示了水滴与胶体相互作用机理。（2）实验研究了制冷温度、凝结时间和胶体预固化度对水滴凝结的影响规律，并获取了大小、间距和截面形貌可控的微结构阵列。（3）通过引入牺牲聚合物层代替空气层，实现了微结构截面形貌的调控，同时在不改变微结构大小的情况下，单独实现微结构间距的调控。（4）通过改变制冷温度工艺参数，以及引入两步制冷，实现了微结构曲率的连续调控。（5）开展了表面微结构的LED封装应用研究，实现了多基色LED白光模块光效的显著提升和空间颜色均匀性的有效改善，同时，实现了绿光LED、深紫外LED和荧光玻璃转换白光LED出光效率的显著提升。（6）对多基色LED封装和应用技术进行了探索性研究。相关论文已在Soft Matter、ACS Photonics、Optical Materials Express、Journal of Applied Physics、IEEE Photonics Journal、人工晶体学报等期刊中发表，SCI收录论文5篇；申请专利13项（5项发明专利，8项实用新型专利），其中授权10项（2项发明专利，8项实用新型专利）；参加国际学术会议1人次，国内学术会议1人次。本课题为无荧光粉多基色LED按需照明技术的发展打下了坚实的基础，对下一代半导体照明技术的发展有重要应用价值。