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

基于薄膜的碲化镉(CdTe)光伏(PV)组件的制造成本目前低于每瓦1美元，这还不到晶体硅光伏成本的50%。因此，基于CdTe的光伏系统已经在许多地方达到了电网平价。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商，该装置的太阳能转换效率必须提高到目前16%的水平以上。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。本研究将致力于加深对多晶镉镉薄膜的基本认识，为提高镉镉太阳电池的效率奠定基础。历史上，镉镉薄膜太阳电池的制备一直采用简单的沉积工艺和热处理的经验优化方法。一个关键的器件特性，即吸收材料中的掺杂水平，从来没有被故意控制或调整过。CdTe太阳能电池中的掺杂水平是在太阳能电池制造过程中的不同工艺步骤引入的几个杂质的结果。这项研究将集中在通过大气压蒸气传输过程来沉积多晶CdTe薄膜，该过程允许控制沉积条件。这一过程将可控地掺杂薄膜，从而提供了一种确定将光伏效率提高到20%的实际极限所需的p型掺杂水平的方法。所提出的研究具有创新性，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，因为它确定了使镉镉太阳能电池的效率高于硅光伏，但成本更低所需的根本性突破。广泛影响提高镉镉太阳能电池的效率将导致更低的制造成本，并允许清洁发电渗透到世界各地的电力市场，包括许多贫穷和不发达的国家。拟议的教育活动将在快速增长的光伏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外展活动。具体地说，REU的所有学生除了他们的研究活动外，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，接待当地小学生半天，并让他们参与实践太阳能活动。REU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成部分，旨在让南佛罗里达大学电气工程专业的所有本科生接触到光伏概念。对II-VI化合物半导体光伏器件的研究将被整合到电气工程课程的必修课中，每年将有150名学生参加。

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.