Developing the Path Toward Realizing the Full Potential of II-VI Based Photovoltaic Materials

薄膜碲化镉（CdTe）光伏（PV）组件的制造成本目前低于每瓦1美元，不到晶体硅光伏成本的50%。因此，基于cdte的光伏系统在许多地方已经达到了电网平价。然而，为了使这种具有成本效益的光伏技术成为未来重要的电力生产者，该设备的太阳能转换效率必须超越目前16%的水平。此外，必须提高材料利用率，以减少碲的负荷，这是一种有限的资源。本研究将着重于提高对多晶CdTe薄膜的基本认识，作为提高CdTe太阳能电池效率的基础。从历史上看，碲化镉薄膜太阳能电池是通过简单的沉积技术和热处理的经验优化来制造的。一个关键的器件特性，吸收材料中的掺杂水平，从来没有被有意地控制或调整过。CdTe太阳能电池中的掺杂水平是在太阳能电池制造过程中不同加工步骤中引入的几种杂质的结果。本研究将集中于多晶碲化镉薄膜的沉积，通过大气压蒸汽输送过程，允许沉积条件的控制。该工艺将可控地掺杂薄膜，因此提供了一种方法来确定将PV效率提高到20%的实际极限所需的p型掺杂水平。提出的研究是创新的，因为它将使用气相元素沉积技术来控制掺杂和缺陷形成过程。这项研究具有潜在的变革性，因为它确定了制造效率优于硅PV但成本更低的CdTe太阳能电池所需的基本突破。更广泛的影响提高碲化镉太阳能电池的效率将降低制造成本，并使清洁能源进入世界各地的电力市场，包括许多贫穷和不发达国家。拟议的教育活动将在快速发展的光电领域培训本科生和研究生，该领域目前严重缺乏工程师。现有的REU计划将用于推动教育和推广活动。具体来说，所有REU学生除了研究活动外，还将担任太阳能光伏大使，在那里他们将举办一年一度的太阳能研讨会，邀请当地小学生参加半天的太阳能实践活动。REU的学生还将协助开发一系列模块，这些模块将用于电子材料和半导体器件课程。这些模块将作为这些课程的实验组件，旨在向南佛罗里达大学电气工程专业的所有本科生展示光伏概念。II-VI化合物半导体光伏器件的研究将被纳入电气工程课程的必修课程，每年将达到150名学生。

0967861FerekidesIntellectual MeritManufacturing costs for thin film cadmium telluride-based (CdTe) photovoltaic (PV) modules are currently below $1 per watt, which is less than 50% the cost of crystalline silicon PV. Consequently, CdTe-based PV systems have reached grid parity in many locations. However, in order for this cost-effective PV technology to become a significant producer of electricity for the future, the solar energy conversion efficiency of the device must be advanced beyond the current level of 16%. Furthermore, material utilization must be improved in order to reduce tellurium loading, which is a limited resource. This research will focus on improving the fundamental understanding of polycrystalline CdTe thin films as the basis to improve the efficiency of CdTe solar cells.Historically, CdTe thin film solar cells have been fabricated using empirical optimization of simple deposition technologies and heat treatments. A key device characteristic, the doping level in the absorber material, has never been intentionally controlled or tuned. Doping levels in CdTe solar cells are the result of several impurities introduced at various processing steps during the solar cell fabrication process. This research will focus on the deposition of polycrystalline CdTe films by an atmospheric pressure vapor transport process that allows for control of the deposition conditions. This process will controllably dope the thin films, and therefore provides a means to determine the p-type doping levels required to advance the PV efficiency towards the practical limit of 20%.The proposed research is innovative because it will use a vapor elemental deposition technique to control the doping and defect formation process. The research is potentially transformative because it identifies the fundamental breakthroughs needed to make CdTe solar cells with efficiency superior to silicon PV but with lower cost.Broader ImpactImproving the efficiencies of CdTe solar cells will lead to lower manufacturing costs and allow cleanly-generated power to penetrate electricity markets around the world, including many poor and underdeveloped nations. The proposed education activities will train students at both the undergraduate and graduate levels in the fast growing field of photovoltaics, which currently has a significant shortage of engineers. Existing REU programs will be used to drive the education and outreach activities. Specifically, all REU students, in addition to their research activities, will also serve as Ambassadors for Solar PV, where they will conduct an annual Solar Energy Workshop which hosts local elementary school students for a half day and gets them involved in hands-on solar energy activities. The REU students will also assist with the development of a series of modules that will be used in the Electronic Materials and Semiconductor Device courses. These modules will serve as the lab component for these courses, and are intended to expose all undergraduate students in electrical engineering at University of South Florida to photovoltaics concepts. Research on II-VI compound semiconductor PV devices will be integrated into required courses of the electrical engineering curriculum that will reach 150 students per year.