CAREER: Defects and Polarons in Complex Materials

非技术总结这个职业奖项支持在用于能源、电子和光电子应用的复杂材料中的缺陷的计算建模方面的研究和教育。缺陷在改变许多材料的性能方面起着至关重要的作用，其中一些材料具有高度的技术相关性，对我们的日常生活至关重要。例如，硅和砷化镓等半导体的导电性可以通过添加微量杂质来大幅改变，从而实现目前计算机、智能手机和平板电脑中微芯片中存在的各种微电子设备(如无处不在的晶体管)。另一方面，缺陷可能对器件性能有害，限制太阳能电池效率的缺陷就是这种情况。我们控制缺陷类型和数量的能力决定了给定的材料是否适合设备应用。因此，了解和控制缺陷对于电子和光电子学新材料的发展至关重要。利用电子结构理论和超级计算机的先进方法，PI将研究缺陷在一系列复杂材料中的作用，这些材料表现出一系列令人兴奋的物理特性。这项研究可能会增强现有的性能，并可能导致发现新的性能，可以用于新的设备设计。此外，该项目将具有重大的教育价值，包括对研究生和K-12高中生的培训。这些研究生将学习尖端的计算方法和材料理论的先进概念；他们还将参加一个外展项目，该项目涉及向高中生教授科学编程，吸引他们进入科学和技术职业生涯。通过暑期实习，高中生将致力于开发数据操作工具，帮助研究生实现复杂的数据可视化。这些工具将通过PI的研究网站免费提供。TECHNICAL SUMMARY这个职业奖项支持在用于能源、电子和光电子应用的复杂材料中缺陷和电荷局部化的计算建模方面的研究和教育。缺陷的存在对大多数材料的性能有很大影响。例如，在半导体中添加微量的杂质可以极大地改变其导电性几个数量级，将良好的绝缘体转变为优秀的导体。缺陷也可能损害器件性能，例如在太阳能电池的情况下，缺陷会导致不想要的非辐射载流子复合，并强烈影响效率。基于密度泛函理论的计算机模拟已成为研究各种类型材料中缺陷的有力工具，提供了有关浓度、电学和光学活动的信息。这些计算经常通过提供在原子尺度上难以探测的重要性质和现象来补充实验。在这个项目中，PI将使用最先进的计算方法来研究缺陷在由具有部分填充的d或f壳层的元素组成的氧化物中的作用。感兴趣的材料包括钙钛矿、层状钙钛矿和焦绿石。这些材料有可能实现新的器件和功能，因为它们最有趣的性质受到杂质和缺陷的存在的强烈影响。这个项目将促进对缺陷和杂质对这些复杂材料的电子和光学性质的影响的基本理解。作为实现器件应用的关键一步，该项目将提供关于平衡缺陷浓度、电学和光学活动以及缺陷与电荷载流子和迁移之间的关系的信息。最终，它将有助于识别对器件中的材料性能不利的缺陷，并将提供基础，通过掺杂或合金化来设计缺陷，以增强或拓宽材料的功能。此外，该项目将具有重大的教育价值，包括对研究生和K-12高中生的培训。这些研究生将学习尖端的计算方法和材料理论的先进概念；他们还将参加一个外展项目，该项目涉及向高中生教授科学编程，吸引他们进入科学和技术职业生涯。通过暑期实习，高中生将致力于开发数据操作工具，帮助研究生实现复杂的数据可视化。这些工具将通过PI的研究网站免费提供。

NONTECHNICAL SUMMARYThis CAREER award supports research and education on the computational modelling of defects in complex materials that are used for energy, electronics, and optoelectronics applications. Defects play a crucial role in altering the properties of many materials, some of which are of high technological relevance and central to our daily life. For example, the electrical conductivity of semiconductors such as silicon and gallium arsenide can be drastically modified by adding minute concentrations of impurities, enabling a variety of microelectronic devices (such as the ubiquitous transistor) that are present in the microchips inside our current computers, smart phones, and tablets. On the other hand, defects can be detrimental to device performance, as is the case for defects that limit the efficiency of solar cells. Our ability to control the type and amount of defects present determines if a given material will be suitable for device applications. Understanding and controlling defects is therefore crucial to the development of novel materials for electronics and optoelectronics. Using advanced methods of electronic structure theory and supercomputers, the PI will investigate the role of defects in a series of complex materials that exhibit an array of exciting physical properties. The research may enhance the existing properties, and could lead to the discovery of new ones that can be used in novel device designs.In addition, this project will have significant educational value, incorporating training of graduate and K-12 high-school students. The graduate students will learn cutting-edge computational methods and advanced concepts in materials theory; they will also participate in an outreach program that involves teaching scientific programing to high-school students, enticing them to a career in science and technology. Through summer internships, high-school students will work on developing data-manipulation tools that will help the graduate students with complex data visualization. The tools will be freely available through the PI's research website.TECHNICAL SUMMARYThis CAREER award supports research and education on the computational modelling of defects and charge localization in complex materials that are used for energy, electronics, and optoelectronics applications. The properties of most materials are strongly affected by the presence of defects. For example, adding minute concentrations of impurities to a semiconductor can drastically change its electrical conductivity by several orders of magnitude, transforming a good insulator into an excellent conductor. Defects can also be detrimental to device performance, as in the case of solar cells, where defects cause unwanted nonradiative carrier recombination, and strongly impact efficiency. Computer modelling based on density functional theory has turned into a powerful tool in the study of defects in various types of materials, providing information on concentrations, and on electrical and optical activities. These calculations often complement experiments by giving access to important properties and phenomena that are difficult to probe at the atomic scale. In this project the PI will use state-of-the-art computational methods to investigate the role of defects in oxides made of elements with partially filled d or f shells. The materials of interest include perovskites, layered perovskites, and pyrochlores. These materials have potential to enable novel devices and functionalities, as their most interesting properties are strongly influenced by the presence of impurities and defects. This project will advance fundamental understanding of the impact of defects and impurities on the electronic and optical properties of these complex materials. In a crucial step towards enabling device applications, the project will provide information on equilibrium defect concentrations, electrical and optical activities, and the relation between defects and charge carriers and migration. Ultimately, it will serve to identify defects that are detrimental to materials performance in devices, and will provide a basis to engineer defects, through doping or alloying, to enhance or broaden materials functionality.In addition, this project will have significant educational value, incorporating training of graduate and K-12 high-school students. The graduate students will learn cutting-edge computational methods and advanced concepts in materials theory; they will also participate in an outreach program that involves teaching scientific programing to high-school students, enticing them to a career in science and technology. Through summer internships, high-school students will work on developing data-manipulation tools that will help the graduate students with complex data visualization. The tools will be freely available through the PI's research website.