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

技术摘要：用节能的磷光体转换发光二极管（pc-LED）取代传统灯泡是最简单和最有前途的方法之一，可以大大降低电力消耗。这些装置通常基于蓝色-（450 nm）或UV-（370-410 nm）发光二极管（LED），其涂覆有封装在光学透明聚合物中的稀土取代的无机磷光体。组合起来，这些发射光产生功能性和有效的白色光。不幸的是，有效地转换LED发射并产生白色光所必需的无机磷光体的可用性和种类是有限的，这增加了pc-LED的前期成本并抑制了它们的广泛采用。已知的磷光体还通常是热绝缘氧化物或氮化物，这导致在LED激发下的极端操作温度（高于150摄氏度），这会降低磷光体性能。因此，下一代pc-LED需要开发具有增强的热性能的新型高效无机磷光体，以降低其成本并鼓励取代传统灯泡。该NSF CAREER奖项目由材料研究部的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，以针对具有改进的热响应的新型无机磷光体，使其能够在极端环境中工作。每个研究步骤的结果都会反馈到原始的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，特别关注参与人数不足的群体。这包括新成立的“计算化学靴子营”，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。强调使用计算机理解化学的重要性，同时也提供动手研究的机会，导致新一代的STEM毕业生谁是全球竞争力的劳动力做好准备。非技术摘要：这个NSF职业奖，由材料研究部的固态和材料化学计划支持，解决了全球需要开发更高效的光源，以取代传统的白炽灯和荧光灯泡。仅在美国，照明就占总电能使用量的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了1.3亿吨碳。固态白色照明使用涂有称为磷光体的发光粉末的蓝色发光二极管（LED），已经成为能够取代白炽灯和荧光灯的高效、持久的光源。新的发光二极管，发射紫外光最近被认为是芯片，可以产生一个更好的光源。然而，为了利用这种技术，有必要发现新的、有效的磷光体系统，其可以将紫外LED光转换成白色光。该CAREER奖的研究和教育计划支持休斯顿大学的Jakoah Brgoch教授建立新的计算和机器学习技术，这些技术能够提高识别新荧光粉的速度。然后，这些信息可以用于指导Brgoch小组对最有前途的磷光体系统的合成，其特性可以使用计算方法进行分析，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，而且还可以通过识别新的和改进的材料来改变照明行业。此外，该奖项用于提高休斯顿大学本科生研究的参与率，特别注重参与代表性不足的群体。这些努力包括新成立的“计算化学靴子营”，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。强调使用计算机理解化学的重要性，同时也提供动手研究的机会，导致新一代的STEM毕业生为全球竞争力的劳动力做好准备。该奖项反映了NSF的法定使命，并通过使用基金会的智力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.