SusChEM: Atomic Structure and Dynamic Behaviors of Extended Defects in Earth-Abundant Solar-Cell Materials

SusChEM：地球丰富的太阳能电池材料中扩展缺陷的原子结构和动态行为

• 批准号: 1506535
• 负责人: Xiaoqing Pan
• 金额: $ 40万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506535&HistoricalAwards=false
• 关键词: SusChEM; Atomic; Structure; Dynamic; Behaviors

Nontechnical Description: The solar-cell material CZTS is made of the low-cost, Earth-abundant elements Cu, Zn, Sn, S, and Se. Challenges to the development of high-efficiency CZTS solar cells include control of impurities and defects. This project is designed to gain a fundamental understanding of the atomic structure and local properties of defects in CZTS under electrical and optical excitations, using state-of-the-art transmission electron microscopy (TEM) in combination with novel in-situ TEM methods developed in the Principle Investigator's lab. These new techniques will allow us to directly probe the atomic structure of individual defects and the responses of those defects to an applied electric field and/or light illumination providing for the determination of the atomic scale structure-property relationships of individual defects. The result will be knowledge needed for the optimization of the material's microstructure and composition, advancing the development of low-cost and sustainable materials with improved properties for solar energy technology. In addition, this project provides a wide range of opportunities for the interdisciplinary education and training of undergraduate and graduate students needed in both industry and academic research today.Technical Description: This SusChEM project is to study the structure and dynamic behaviors of Earth-abundant solar-cell materials using a combination of advanced aberration-corrected transmission electron microscopy (TEM) and novel in-situ TEM techniques. The research primarily focuses on thin films of kesterite Cu2ZnSn(S,Se)4 (CZTS), a candidate material to replace Cu(In,Ga)Se2 (CIGS). Because of the polycrystalline nature and the co-existence of multiple impurity phases in CZTS thin films, it is critical, but very challenging to understand the role of defects and interfaces in controlling the electrical properties and solar conversion efficiency. In this project, the PI combines the state-of-the-art aberration-corrected TEM imaging, spectroscopy, and the novel in-situ techniques recently developed in his lab to study the atomic structure and dynamic behaviors of individual defects, grain boundaries, and interfaces in CZTS materials. Spatially resolved cathode-luminescence and scanning tunneling microscopy holders with optical excitation, combined with holography and electron energy-loss spectroscopy (EELS), are used to identify the active and inactive regions of defects (grain boundaries, interfaces, secondary phase boundaries, etc.), while the atomic structure, chemical composition and local electronic properties of the same regions are determined by TEM imaging and spectroscopy with atomic resolution. In combination with the optoelectronic properties measured from the same material, the role of defects in controlling the materials properties can be understood.

非技术描述：太阳能电池材料CZTS是由低成本，地球上丰富的元素Cu， Zn, Sn， S和Se制成的。开发高效CZTS太阳能电池面临的挑战包括杂质和缺陷的控制。该项目旨在利用最先进的透射电子显微镜（TEM）和主要研究者实验室开发的新型原位透射电子显微镜方法，对电和光激发下CZTS的原子结构和局部缺陷特性有一个基本的了解。这些新技术将使我们能够直接探测单个缺陷的原子结构以及这些缺陷对外加电场和/或光照的响应，从而确定单个缺陷的原子尺度结构-性质关系。结果将是优化材料的微观结构和成分所需的知识，推动低成本和可持续材料的发展，改善太阳能技术的性能。此外，该项目为当今工业和学术研究所需的本科生和研究生提供了广泛的跨学科教育和培训机会。技术描述：这个SusChEM项目是利用先进的像差校正透射电子显微镜（TEM）和新型原位TEM技术的结合来研究地球上丰富的太阳能电池材料的结构和动态行为。研究主要集中在Cu2ZnSn(S,Se)4 （CZTS）薄膜上，这是替代Cu(In,Ga)Se2 （CIGS）的候选材料。由于CZTS薄膜的多晶性质和多杂质相共存，因此了解缺陷和界面在控制电学性能和太阳能转换效率方面的作用至关重要，但也是非常具有挑战性的。在这个项目中，PI结合了最先进的像差校正TEM成像，光谱学和他实验室最近开发的新型原位技术，研究了CZTS材料中单个缺陷，晶界和界面的原子结构和动态行为。利用光学激发的空间分辨阴极发光和扫描隧道显微镜，结合全息成像和电子能量损失谱（EELS）技术，对缺陷的活性区和非活性区（晶界、界面、二次相界等）进行了识别，同时利用具有原子分辨率的TEM成像和光谱技术确定了同一区域的原子结构、化学组成和局部电子性质。结合从同一材料测量的光电性能，可以理解缺陷在控制材料性能中的作用。