Inorganic Distributed Nanocrystal Heterojuntion Solar Cells

随着人们对开发更便宜、更高效的光伏材料的兴趣日益高涨，半导体纳米晶体已经成为一种很有前途的候选材料，它可能作为光收集元件提供重大好处。这些材料具有许多理想的特性。纳米晶体的电子和光学特性是可调节的，这将允许具有大截面结构的太阳光谱的最佳覆盖。它们与溶液环境和低温加工的兼容性对实用和经济高效的生产具有吸引力。除了具有转变低成本太阳能转换技术的潜力之外，基于最近发现的高效多激子生成过程，基于纳米晶体的太阳能电池也具有大幅提高效率的潜力。在这个过程中，单个入射光子可以产生多个电子-空穴对，从而利用吸收的光子能量超过带隙，否则这些能量将以热量的形式损失。目前，纳米晶体太阳能电池的发展由于缺乏对界面电子特性的分子水平控制而受到限制。这一领域最初的努力集中在基于纳米晶体和共轭聚合物混合物的有机-无机杂化器件上。这种方法存在于光生载流子的提取较差的问题，并表明需要提高对界面特性的理解和控制，以充分利用这些材料独特的光子收集特性。该项目由Engstrom和Hanrath领导，利用他们在表面科学、纳米晶体合成和器件制造方面的专业知识，研究界面电荷转移的基本原理，并将定制的纳米晶体界面集成到新型全无机分布异质结太阳能电池中。他们的工作目标是：(1)了解和控制纳米晶体界面上的电子结构和输运特性；(2)应用这些知识来设计优化界面，以便在分布式异质结太阳能电池中使用半导体纳米晶体。除了科学活动之外，该项目还将邀请一些从事太阳能研究的教师和学生参加一个关于研究伦理的研讨会。太阳能处于研究的前沿，容易受到可能导致许多不良后果的实践的影响。从提案的撰写和审查到实验室的日常活动，教育社区如何正确地进行研究，将更好地培养一个富有成效的研究环境。最后，该项目与一些外联和教育活动密切结合。我们与康奈尔大学物理教师研究所合作，接触到高中教师和学生，让他们参与到这个领域令人兴奋的进步中来。

CBET-0828703HanrathWith surging interest in the development of cheaper and more efficient photovoltaic Materials semiconductor nanocrystals have emerged as a promising candidate potentially offering major benefits as light harvesting elements. These materials have a number of desirable characteristics. The electronic and optical properties of nanocrystals are size-tunable, which will allow optimal coverage of the solar spectrum by structures with large cross-sections. Their compatibility with solution environments and low-temperature processing are attractive for practical and cost-effective production. Beyond their potential to transform low-cost solar energy conversion technology, nanocrystal-based solar cells also have the potential for substantially increased efficiency, based on the recently-discovered process of efficient multi-exciton generation. In this process a single incident photon can generate multiple electron-hole pairs and thereby utilize the absorbed photon energy in excess of the band gap, which would otherwise be lost as heat.Progress in the development of nanocrystal-based solar cells is currently limited by the lack of molecular-level control over the electronic properties at the interface. Initial efforts in this field have focused on hybrid organic-inorganic devices based on blends of nanocrystals and conjugated polymers. This approach suffered from poor extraction of photogenerated carriers and illustrated that improved understanding and control over the interface properties are required to fully harness the unique photon harvesting properties of these materials. The project led by Engstrom and Hanrath leverages their expertise in surface science, nanocrystal synthesis and device fabrication to study fundamental principles of interface charge transfer and to integrate tailored nanocrystal interfaces into novel all-inorganic distributed heterojunction solar cells. The goals of their work are: (1) to understand and control the electronic structure and transport properties at nanocrystal interfaces and (2) to apply that knowledge to engineer optimized interfaces for the use of semiconductor nanocrystals in distributed heterojunction solar cells.Beyond the scientific activities, the project will engage a number of faculty and students involved in solar energy research in a workshop on research ethics. Solar energy, being on the frontier of research, is susceptible to practices that might lead to a number of undesirable outcomes. Educating the community about the proper conduct of research, ranging from the writing of and review of proposals to day-to-day activities in the lab will better foster a productive research environment. Finally, the project is closely integrated with a number of outreach and educational activities. We have aligned with the Cornell Institute for Physics Teachers to reach out to high school teachers and students and engage them in the exciting advances being made in the field.