Design, Synthesis and Modeling of Luminescent Ceramics for Application in Solid State Lighting

用于固态照明的发光陶瓷的设计、合成和建模

• 批准号: 1411192
• 负责人: Joanna McKittrick
• 金额: $ 64万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1411192&HistoricalAwards=false
• 关键词: Design; Synthesis; Modeling; Luminescent; Ceramics

NON-TECHNICAL DESCRIPTION: Lighting accounts for 22% of the total US electrical energy use, which translates to $50 billion per year spent on lighting accompanied with 130 million tons of carbon emitted into the atmosphere from fossil fuel plants. Solid state lighting, based on blue-emitting light emitting diodes with a luminescent powder (phosphor), has emerged as highly efficient, long lasting light sources to replace incandescent and fluorescent lighting. The phosphor market in the US for white-emitting LEDs is currently $500M/year and is expected to reach $1B/year by 2015. Identifying new phosphors in a reliable and systematic way with high quantum efficiency and thermal stability is crucial for these new energy saving devices. Nanophosphors represent an exciting opportunity to reduce light scattering, thereby improving the extraction efficiency. This work is interdisciplinary and spans the fields of materials science, optical properties, chemistry, and atomic scale modeling that involves both experiments and modeling. Graduate students are trained in sophisticated electron microscopy techniques, theoretical and computational methods. Diversity efforts are continued and strengthened. The involvement of students from a Hispanic-serving Institution and a middle/high school that serves low-income students are included. New classes are developed for the graduate curriculum.TECHNICAL DETAILS: Solid state lighting, based on blue-emitting (450 nm) light emitting diodes (LEDs) with a luminescent powder (phosphor), has emerged as highly efficient, long lasting light sources to replace incandescent and fluorescent lighting. New diodes that emit in the near UV (370-410 nm) have recently been recognized as chips that could improve the extraction efficiency of the light source. This new development requires the discovery of new phosphor systems in the nano-sized range to fully exploit this new technology. The phosphors used in this work are wide band gap materials (hosts) that contain a small amount of activator (rare-earth element). Depending on the host:activator combination, colors across the visible spectrum can be obtained. This project aims at validating the following three hypotheses: (1) using an empirical approach combined with first principles modeling, new high quantum efficiency, thermally stable phosphors can be identified for near UV LED white-emitting light sources, (2) the low quantum efficiency of nanosized phosphors can be determined and perhaps overcome and (3) modeling using a combination of semi-local and hybrid density functional theory will provide insight on the mechanisms for photon absorption and emission of new phosphor systems, the phase, chemical and thermal stability and on the quantum efficiency of nanosized phosphors. These hypotheses are tested by conducting by a variety of experimental and computational tasks: (1) the design of phosphors in which the excitation energy lies in the near UV spectral range of 370-410 nm, (2) the design of phosphors in which sensitization is via the excitation of complex functional groups, (3) using a combination of analytical tools, a systematic approach will be conducted to evaluate the factors behind the low quantum efficiency of nanosized phosphors ( 200 nm). Surface and bulk analyses will identify the local environment of the activator and the traps that quench the luminescence and (4) a hierarachy of first principles methods are used to investigate the phase stability, aqueous stability, thermal stability and electronic structure of the phosphor materials to be synthesized and tested experimentally. The theoretical calculations are used to guide and interpret experiments and also to guide which compositions and structures of the phosphor materials are most promising for UV LED applications.

非技术描述：照明占美国总电能使用量的22%，相当于每年花费500亿美元用于照明，同时化石燃料工厂向大气排放1.3亿吨碳。 基于具有发光粉末（磷光体）的蓝色发光二极管的固态照明已经成为替代白炽灯和荧光灯的高效、持久的光源。 美国白光LED的荧光粉市场目前为每年5亿美元，预计到2015年将达到每年10亿美元。 以可靠和系统的方式识别具有高量子效率和热稳定性的新磷光体对于这些新的节能设备至关重要。 纳米荧光粉代表了一个令人兴奋的机会，以减少光散射，从而提高提取效率。这项工作是跨学科的，跨越了材料科学，光学特性，化学和原子尺度建模，涉及实验和建模领域。研究生接受复杂的电子显微镜技术、理论和计算方法的培训。 多样性工作继续进行并得到加强。 包括来自西班牙裔服务机构和为低收入学生服务的初中/高中的学生的参与。 技术优势：固态照明技术是一种基于蓝光（450 nm）发光二极管（LED）和荧光粉（磷光体）的高效率、长寿命的光源，已取代白炽灯和荧光灯。 在近紫外（370-410 nm）发射的新二极管最近被认为是可以提高光源提取效率的芯片。 这一新的发展需要在纳米尺寸范围内发现新的磷光体系统，以充分利用这一新技术。 在这项工作中使用的磷光体是宽带隙材料（主机），其中包含少量的激活剂（稀土元素）。取决于主体：活化剂组合，可以获得整个可见光谱的颜色。 本项目旨在验证以下三个假设：（1）使用与第一原理建模相结合的经验方法，可以识别用于近UV LED发白光光源的新的高量子效率、热稳定的磷光体，（2）纳米尺寸磷光体的低量子效率可以被确定并且可能被克服，以及（3）使用半-局域和混合密度泛函理论将提供关于新磷光体系统的光子吸收和发射机制、纳米尺寸磷光体的相、化学和热稳定性以及量子效率的见解。这些假设通过各种实验和计算任务进行测试：（1）激发能位于370-410 nm的近UV光谱范围内的磷光体的设计，（2）通过激发复杂官能团来敏化的磷光体的设计，（3）使用分析工具的组合，将进行系统的方法来评估纳米尺寸磷光体（200 nm）的低量子效率背后的因素。 表面和体相分析将确定激活剂的局部环境和猝灭发光的陷阱;（4）使用第一性原理方法的层次来研究待合成和实验测试的磷光体材料的相稳定性、水稳定性、热稳定性和电子结构。 理论计算用于指导和解释实验，并指导哪些磷光体材料的组成和结构最有前途的UV LED应用。