SOLAR: Phase-Field Crystal Modeling and Analytical Surface Analysis of Iron Pyrite (FeS2) for Thin-Film Photovoltaics

在这个由化学、材料研究和数学科学系资助的项目中，加州大学欧文分校的Matthew D.Law、John C.Hemminger和John Lowengrub教授将研究在薄膜光伏(PV)中使用黄铁矿。黄铁矿或过硫化铁(FeS_2)是一种研究不足、非常有希望用作光吸收层的半导体。利用这种材料进行太阳能转换有两个关键障碍：难以合成高质量的、物相纯的黄铁矿，以及黄铁矿器件的低光电压。本研究将新的相场晶体(PFC)和密度泛函理论(DFT)模型与有针对性的合成和表面表征工作相结合，通过烧结层溶液沉积的黄铁矿纳米晶和化学气相沉积(CVD)来生长器件级质量的黄铁矿薄膜，并通过合理的退火法和配位化学方法钝化中间能隙状态来固定黄铁矿的光电压。连续体和原子晶体建模(Lowengrub教授，数学)、黄铁矿生长(Law教授，材料科学)和表面表征(Hemminger教授，化学)方面的专家之间的合作为开发富含地球和环境友好的半导体材料提供了一种新的方法。这些特性对于大规模实施太阳能作为替代能源具有重要意义。在这个团队中工作的本科生、研究生和博士后研究人员获得了标准学术课程中不经常遇到的跨学科视角。为了补充这项研究工作，该团队正在为每年约20名高中生开发为期一个月的晶体生长强化暑期课程，作为加州州立大学数学与科学暑期学校(COSMOS)的一部分。这门课程为学生提供了学习数学理论、使用最先进的模拟工具以及在实验室学习结晶学和太阳能的机会。研究小组还参与了在奥兰治县探索科学中心设计和实施关于太阳能和能源利用的互动教育展览，包括对运行中的光伏阵列进行实时监测。预计每年将有70,000名K-12学生和445,000名社区成员访问该网站。

In this project funded by the Divisions of Chemistry, Materials Research, and Mathematical Sciences, Professors Matthew D. Law, John C. Hemminger, and John Lowengrub of the University of California-Irvine will study the use of iron pyrite in thin-film photovoltaics (PV). Pyrite or iron persulfide (FeS2) is an under-researched, extremely promising semiconductor for use as the light-absorbing layer. There are two key hurdles to utilizing this material for solar energy conversion: the difficulty in synthesizing high-quality, phase-pure pyrite and the low photovoltage of pyrite devices. This research will combine novel phase field crystal (PFC) and density functional theory (DFT) models with targeted synthetic and surface characterization efforts to grow device-quality pyrite thin films by sintering layers of solution-deposited pyrite nanocrystals and by chemical vapor deposition (CVD), and to fix the pyrite photovoltage by passivating mid-gap states via judicious annealing and coordination chemistry approaches. This collaboration between experts in continuum and atomistic crystal modeling (Prof. Lowengrub, Mathematics), pyrite growth (Prof. Law, Materials Science), and surface characterization (Prof. Hemminger, Chemistry) provides a new approach to developing semiconductor materials that are earth-abundant and environmentally friendly. Such properties are important for the large-scale implementation of solar energy as an alternative energy source. Undergraduate, graduate and postdoctoral researchers working in this team gain interdisciplinary perspectives not often encountered in standard academic curricula. To complement the research effort, the team is developing an intensive, month-long summer course on crystal growth for ~20 high school students annually as part of the California State Summer School for Mathematics and Science (COSMOS) at UCI. This course provides students with the opportunity to learn mathematical theory, use state-of-the-art simulation tools, and learn about crystallography and solar energy in the laboratory. The research team is also involved in the design and implementation of an interactive educational exhibit on solar energy and energy use, including real-time monitoring of an operating photovoltaic array, at the Discovery Science Center of Orange County. This site is expected to be visited by 70,000 K-12 students and 445,000 members of the community each year.