CAREER: Targeting novel phosphors for the next generation of solid state white lighting

技术摘要：用高效节能的荧光粉转换发光二极管（pc-LED）取代传统灯泡是最简单、最有前途的大幅降低电力消耗的方法之一。这些器件通常是基于蓝光（450纳米）或紫外线（370-410纳米）发光二极管（led），这些发光二极管被包裹在一个光学透明的聚合物中，由稀土取代的无机荧光粉包裹。结合在一起，这些发射光产生功能和高效的白光。不幸的是，有效转换LED发光并产生白光所需的无机荧光粉的可用性和种类有限，这增加了pc-LED的前期成本，并抑制了它们的广泛采用。已知的荧光粉通常也是隔热氧化物或氮化物，这导致LED激发下的极端工作温度（高于150摄氏度），从而降低荧光粉的性能。因此，下一代pc- led需要开发具有增强热性能的新型高效无机荧光粉，以降低其成本并鼓励替代传统灯泡。这个NSF CAREER奖项目由材料研究部固态和材料化学项目支持，建立了一种研究方法，将机器学习、计算和材料合成联系起来，以改善热响应的新型无机荧光粉为目标，使其能够在极端环境中运行。每个研究步骤的结果反馈到原始机器学习和计算模型中，以提高模型的准确性和可靠性。此外，该职业奖用于提高休斯顿大学本科生研究的参与率，特别关注未被充分代表的群体。这包括新成立的“计算化学训练营”，为STEM学生以及休斯顿地区本科院校和社区学院的教师提供学习计算化学基础知识的机会。强调使用计算机来理解化学的重要性，同时也提供了动手研究的机会，这将导致新一代STEM毕业生为全球竞争的劳动力做好准备。摘要：该奖项由美国国家科学基金会材料研究部固态与材料化学项目支持，旨在解决全球开发更高效光源以取代传统白炽灯和荧光灯的需求。仅在美国，照明就占总电能使用量的22%，这意味着每年在照明上的花费为500亿美元，同时化石燃料工厂向大气中排放了1.3亿吨碳。固态白光照明是一种高效、持久的光源，可以取代白炽灯和荧光灯，它使用涂有荧光粉的蓝色发光二极管（led）。发出紫外线的新型led最近被认为是可以产生更好光源的芯片。然而，为了利用这一技术，有必要发现新的，高效的荧光粉系统，可以将紫外线LED光转换成白光。该职业奖的研究和教育项目支持休斯顿大学的Jakoah Brgoch教授建立新的计算和机器学习技术，这些技术能够提高新荧光粉的识别速度。这些信息可以用来指导Brgoch小组合成最有前途的荧光粉系统，其性质可以使用计算方法来分析，以了解增强的光学响应。这种合作研究方法不仅可以带来更高性能的材料，而且还具有通过识别新的和改进的材料来改变照明行业的潜力。此外，该奖项还用于提高休斯顿大学本科生研究的参与率，特别侧重于吸引代表性不足的群体。这些努力包括新成立的“计算化学训练营”，为STEM学生以及休斯顿地区本科院校和社区学院的教师提供学习计算化学基础知识的机会。强调使用计算机来理解化学的重要性，同时也提供了动手研究的机会，这将导致新一代STEM毕业生为全球竞争的劳动力做好准备。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Technical Abstract:Replacing a traditional light bulb with an energy-efficient, phosphor converted-light emitting diode (pc-LED) is one of the simplest and most promising methods to dramatically decrease electricity consumption. These devices are conventionally based on blue- (450 nm) or UV- (370-410 nm) emitting light emitting diodes (LEDs) that are coated with a rare-earth substituted inorganic phosphor encapsulated in an optically transparent polymer. In combination, these emissive lights produce a functional and efficient white light. Unfortunately, the availability and variety of inorganic phosphors that are necessary to efficiently convert the LED emission and create white light are limited, which increases the upfront cost of pc-LEDs and inhibits their widespread adoption. The known phosphors are also often thermally insulating oxides or nitrides, which lead to extreme operating temperatures (above 150 Celsius) under LED excitation that can degrade phosphor performance. Consequently, the next generation of pc-LEDs requires the development of new, efficient inorganic phosphors with enhanced thermal properties to reduce their cost and encourage the replacement of traditional light bulbs. This NSF CAREER award project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, establishes a research approach that connects machine learning, computation, and materials synthesis to target new inorganic phosphors with improved thermal response allowing them to operate in extreme environments. The results from each research step feed back into the original machine learning and computational models to improve the accuracy and reliability of the models. Further, this CAREER award is used to enhance the participation rate of undergraduate research at the University of Houston, with a particular focus in engaging underrepresented groups. This includes a newly established "Boot Camp in Computational Chemistry" to provide STEM students, as well as faculty at undergraduate institutions and community colleges in the Houston-area, the opportunity to learn the basics of computational chemistry. Emphasizing the importance of using a computer to understand chemistry, while also providing opportunities for hands-on research, leads to a new generation of STEM graduates who are prepared for a globally competitive workforce.Non-technical Abstract:This NSF CAREER award, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, addresses the global need to develop more efficient light sources to replace conventional incandescent and fluorescent bulbs. In the US alone, lighting accounts for 22% of total 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 white lighting, which uses a blue-emitting light emitting diode (LEDs) coated with a luminescent powder called a phosphor, has emerged as highly efficient, long-lasting light source capable of replacing incandescent and fluorescent lighting. New LEDs that emit ultraviolet light have recently been recognized as chips that could yield an even better light source. However, to make use of this technology, it is necessary to discover new, efficient phosphor systems that can convert the ultraviolet LED light into white light. This CAREER award's research and education program support Prof. Jakoah Brgoch at the University of Houston to establish new computational and machine-learning techniques that are capable of increasing the rate at which new phosphors can be identified. This information can then be used to direct the Brgoch group's synthesis towards the most promising phosphor systems, whose properties can be analyzed using computational methods to understand the enhanced optical response. This cooperative research approach not only leads to higher performance materials, but it also has the potential to transform the lighting industry by identifying new and improved materials. Further, this award is used to enhance the participation rate of undergraduate research at the University of Houston, with a particular focus in engaging underrepresented groups. The efforts include a newly established "Boot Camp in Computational Chemistry" to provide STEM students, as well as faculty at undergraduate institutions and community colleges in the Houston-area, the opportunity to learn the basics of computational chemistry. Emphasizing the importance of using a computer to understand chemistry, while also providing opportunities for hands-on research, leads to a new generation of STEM graduates who are prepared for a globally competitive workforce.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.