RUI: Confronting Structural Complexity in the Computational Design and Understanding of Perovskite Materials for Solar Energy Conversion

非技术性总结该奖项支持计算研究，以设计和理解“钙钛矿型”化合物，这是一类具有重要技术价值的材料，具有吸收和利用阳光能量的能力。钙钛矿化合物的通式为ABX3，这意味着它们由三种化学元素组成，比例为1：1：3。在过去的十年里，其中一些化合物在光伏太阳能电池中表现出了希望，这意味着它们可以将阳光直接转化为电能。其他钙钛矿是太阳能光催化剂，这意味着它们可以利用阳光来驱动产生燃料的化学反应。钙钛矿的一个独特特性是，它们的结构可以通过许多微妙的方式进行改变--用不同的元素替换，拉动和扭曲，分层和装饰--以优化它们转换阳光的能力。有了所有这些修改钙钛矿的自由，计算机是预测这些材料中哪些将以期望的方式表现的宝贵工具。在这项研究中，首席研究员(PI)、本科生和硕士研究生将使用计算机来预测和了解为什么原子的取代和移动会影响钙钛矿吸收和转换阳光的能力。此外，研究小组将开发一种新的计算方法，比传统方法更快，以快速和粗略地在大量的钙钛矿材料中搜索感兴趣的特性。该奖项还支持PI的指导和教学活动，以及在以本科为主的西华盛顿大学的课程开发。该奖项将使不同的本科生和硕士学生群体得到培训和指导，并使PI和学生有机会在区域和国家研究会议上展示他们的工作。近年来，PI一直致力于将他的本科物理化学课程“翻转”，设计课堂问题解决和计算机模拟活动，以更积极的方式吸引学生。教育文献中有证据表明，这种方法导致了各种积极的学习结果(特别是在表现较差的学生中)，并通过吸引具有广泛不同学习风格的学生来促进公平和包容。在接下来的几年里，PI将完善和进一步开发这些物理化学课程材料，并开发类似的以学生为中心的培训材料，与他的团队的研究领域相关。这些材料将帮助学生学习计算和固态化学等本科课程很少涉及的领域。技术总结该奖项支持计算研究，以设计和理解用于太阳能转换的钙钛矿化合物。在过去的十年里，卤化物钙钛矿太阳能电池已经成为一项很有前途的快速发展的技术。氧化物钙钛矿也被探索用于太阳光催化。随着合成和器件工程的进步，基于密度泛函理论(DFT)对这些材料的结构和性能的各个方面进行了研究。然而，很大程度上由于与实验相关的钙钛矿超结构和纳米结构的结构复杂性，理论和计算真正处于这一领域的前沿预测的情况有限。为了促进对结构/性质关系的基本理解，并指导实验者寻找新材料，PI、本科生和硕士生将学习卤化物和氧化物钙钛矿的计算阐明和设计方面的三个研究领域。这些项目将使用电子结构计算来：1)使用应变及其与组成和结构扭曲的耦合来调整电子性质；2)识别具有所需性质的新颖、能量稳定的钙钛矿超结构类别；3)开发、测试和部署一种新的半经验方法(基于扩展的Hueckel方法)来快速高通量地筛选复杂的钙钛矿超结构和纳米结构。这些项目将在基本理解、新材料的发现和调整以及方法开发方面推动该领域的发展。该奖项还支持PI的指导和教学活动以及西华盛顿大学的课程开发，该大学主要是一所本科院校。该奖项将使不同群体的本科生(在三年内获得九份暑期研究津贴)和一名硕士学生得到培训和指导，并使PI和学生有机会在区域和国家研究会议上展示他们的工作。学生将学习在本科课程中很少看到的可再生能源和化学关键领域(计算和固态)，并将获得在现代劳动力中日益重视的计算技能(Linux和编程)。在进行这些研究工作的同时，该研究所将为学生开发和评估协同教育材料，形式为固体化学关键主题(例如晶体结构和对称性、X射线衍射、电子能带结构和互易空间)的独立计算机模拟课程。这些课程是PI开发的一套计算机模拟课程的产物，并在本科生物理化学课程中以学生为中心的活动中使用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis RUI award supports computational research to design and understand "perovskite" compounds, a technologically important class of materials with the ability to absorb and harness the energy in sunlight. Perovskite compounds have the general formula ABX3, meaning they consist of three chemical elements in a 1:1:3 ratio. In the past decade, some of these compounds have shown promise in photovoltaic solar cells, meaning they can convert sunlight directly to electricity. Other perovskites are solar photocatalysts, meaning they can use sunlight to drive chemical reactions that generate fuel. A unique property of perovskites is that their structure can be changed in many subtle ways -- substituted with different elements, pulled and twisted, layered and decorated -- to optimize their ability to convert sunlight. With all of this freedom to modify perovskites, computers are valuable tools in predicting which of these materials will behave in desired ways. In this research, the principal investigator (PI), undergraduate, and master's-level students will use computers to predict how and understand why substitutions and movements of atoms affect the ability of perovskites to absorb and convert sunlight. In addition, the research group will develop a new computational method, faster than traditional methods, to quickly and roughly search the huge variety of perovskite materials for properties of interest.The award also supports the PI's mentoring and teaching activities and curriculum development at Western Washington University, a primarily undergraduate institution. The award will enable the training and mentoring of a diverse group of undergraduate and master's students along with opportunities for the PI and students to present their work at regional and national research conferences. In recent years, the PI has worked to "flip" his undergraduate physical chemistry courses, designing in-class problem solving and computer simulation activities to engage students in more active ways. There is evidence in the education literature that this approach leads to a variety of positive learning outcomes (especially among lower-performing students) and promotes equity and inclusion by engaging students with a wide spectrum of different learning styles. In the coming years, the PI will refine and further develop these curricular materials for physical chemistry and develop similar student-centered training materials relevant to his group's research areas. These materials will help students learn about fields such as computational and solid-state chemistry, which are rarely covered in the undergraduate curriculum.TECHNICAL SUMMARYThis RUI award supports computational research to design and understand perovskite compounds for solar energy conversion. In the past decade, halide perovskite solar cells have emerged as a promising and rapidly developing technology. So too have oxide perovskites been explored for solar photocatalysis. Along with advances in synthesis and device engineering, there have been density functional theory (DFT)-based studies of various aspects of the structure and properties of these materials. However, due in large part to the structural complexity of experimentally relevant perovskite superstructures and nanostructures, cases in which theory and computation have truly been on the leading predictive edge of this field have been limited. In order to advance fundamental understanding of structure/property relationships and guide experimentalists in the search for new materials, the PI, undergraduate, and master's-level students will study three research areas in the computational elucidation and design of halide and oxide perovskites. These projects will use electronic structure calculations to: 1) tune electronic properties using strain and its couplings to composition and structural distortion; 2) identify novel, energetically stable classes of perovskite superstructures with desired properties; 3) develop, test, and deploy a new semi-empirical approach (based on the extended Hueckel method) to the rapid high-throughput screening of complex perovskite superstructures and nanostructures. These projects will advance the state of the field in terms of fundamental understanding, discovery and tuning of new materials, and method development.The award also supports the PI's mentoring and teaching activities and curriculum development at Western Washington University, a primarily undergraduate institution. The award will enable the training and mentoring of a diverse group of undergraduate students (with nine summer research stipends over three years) and a master's student, and opportunities for the PI and students to present their work at regional and national research conferences. Students will learn about renewable energy and key areas of chemistry (computational and solid state) that are rarely seen in the undergraduate curriculum, and will gain computational skills (Linux and programming) that are increasingly valued in the modern workforce. In parallel with these research efforts, the PI will develop and assess synergistic educational materials for students, in the form of standalone computer simulation lessons in key topics of solid state chemistry (e.g., crystal structure and symmetry, X-ray diffraction, and electronic band structure and reciprocal space). These lessons are an outgrowth of the suite of computer simulation lessons that the PI has developed and used in student-centered activities in undergraduate physical chemistry courses.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.