Electronic Band Structure Investigations of Complex Multi-Component Oxides for Photovoltaic Applications

技术概述：该奖项支持旨在使用电子结构方法来帮助理解和发现具有光伏系统应用所需特性的材料的计算和理论研究和教育。下一代发展轻型太阳能电池的战略依赖于一种生长在透明导电氧化物衬底上的半导体吸光材料。该衬底在所得到的太阳能电池中充当窗口，但也提供了作为欧姆接触的辅助作用，该欧姆接触允许从光吸收半导体传输光生电荷载流子。本项目采用基于密度泛函理论的计算机模拟方法来研究和预测化学计量比为R2O_3(MO)m的多组分复合氧化物的结构、电学和光学性质。这里，R=三价离子，M=二价离子，以及m=整数。其动机是确定适合于光伏应用的透明导电主机的候选对象。在这方面，有必要确定三价离子和二价离子的哪种选择导致了在不牺牲光传输需求的情况下提供最大导电性的本征掺杂材料。除了考虑最大化载流子数量的方法外，这项研究还探讨了优化载流子迁移率而不是载流子浓度的可能性。研究中的体系涵盖了复杂多组分氧化物的一系列结构和组合特征，并提供了将主族金属氧化物如CaO、Al_2O_3和SiO_2取代传统的In_2O_3、ZnO和SnO_2透明导电氧化物的可能性。该项目中采用的最先进的密度泛函方法的独特预测能力提供了对所建议材料中潜在的物理现象、系统行为以及新的和隐藏的功能的基本理解，并将激励进一步的理论和实验工作。该项目可能会对物理、化学、材料科学家和工程学等学科产生影响。该项目支持吸引和指导攻读理科高级学位的妇女的努力。非技术概述：该奖项支持旨在使用计算机和理论来帮助理解和发现具有光伏系统应用所需特性的材料的计算和理论研究和教育。目前与开发下一代重量更轻、经济可行的太阳能电池相关的问题之一是寻找具有似乎相互矛盾的属性组合的材料。它们不仅应该允许阳光通过，而且还应该能够导电。这项研究使用复杂的计算方法来优化透明导电氧化物材料以实现这一功能。另一个重点是确定如何从对环境更丰富和更安全的金属原子中构建透明的导电氧化物。这一研究项目有助于保持美国的竞争力，并为可持续能源生产带来希望的技术做出贡献。该项目还推动实现了利用计算机和理论来设计具有所需性质的材料的梦想，只知道组成原子的身份。与研究同时进行的是高中、本科生和研究生层面的教育倡议，以及吸引和指导攻读科学高级学位的女性的努力。

TECHNICAL SUMMARY:This award supports computational and theoretical research and education that aims to use electronic structure methods to aid in the understanding and discovery of materials with properties that are desirable for applications in photovoltaic systems. Next generation strategies for the development of light-weight solar cells rely upon a semiconducting light-absorbing material that is grown on top of transparent conducting oxide substrate. The substrate acts as window in the resulting solar cells but also provides a secondary role as the ohmic contact that allows for transport of the photogenerated charge carriers from the light absorbing semiconductor. This project employs density-functional-theory-based computer simulations to study and predict the structural, electronic and optical properties of complex multi-component oxides which form a layered structure with a stoichiometry R2O3(MO)m . Here, R = trivalent ion, M = divalent ion, and m=integer. The motivation is to identify candidates for transparent conducting hosts which are appropriate for photovoltaic applications. In this regard, it is necessary to determine which selection of trivalent and divalent ions lead to intrinsically doped materials that provide a maximal conductivity without sacrificing the need for optical transmission. In addition to considering a means for maximizing the number of charge carriers this research addresses the possibility of optimizing carrier mobilities rather than carrier concentration. The systems under study span a large range of structural and combinatorial peculiarities of complex multicomponent oxides and offer the possibility to incorporate main group metal oxides such as CaO, Al2O3 and SiO2 in place of the traditional In2O3, ZnO and SnO2 transparent conducting oxides.The unique predictive power of the state-of-the-art density functional methods employed in this project provide fundamental understanding of the underlying physical phenomena, the system behavior, as well as novel and hidden functionalities in the proposed materials and will stimulate further theoretical and experimental efforts. This project may have impact across the disciplines of physics, chemistry, materials scientists and engineering. This project supports efforts to attract and mentor women pursuing advanced degrees in the sciences. NON-TECHNICAL SUMMARY:This award supports computational and theoretical research and education that aims to use computers and theory to aid in the understanding and discovery of materials with properties that are desirable for applications in photovoltaic systems. One of the current problems related to development of the next generation of lighter-weight economically viable solar cells is finding materials that have a seemingly contradictory combination of properties. They should at once allow sunlight to pass through but also be able to conduct electrically. This research uses sophisticated computational methods for optimizing transparent conducting oxide materials for this function. An additional emphasis is on determining how to construct transparent conducting oxides from the metal atoms that are more abundant and safer for the environment. This research project helps to keep America competitive and contributes to technologies that hold promise for sustainable energy production. This project also pushes toward realizing the dream of using computers and theory to design materials with desired properties knowing only the identity of the constituent atoms.In parallel with the research are educational initiatives at the high school, undergraduate and graduate level and an effort to attract and mentor women pursuing advanced degrees in the sciences.