Electroactive Organic Materials and Nanoscale Patterning Strategies for Photovoltaic Devices

技术。该项目探索改进太阳能电池的新材料和新策略。社会严重依赖对环境无害的廉价能源，并在今后几年面临危机。基于易于加工的共轭有机材料的光伏器件是具有成本效益的大面积太阳能电池的潜在候选者。该项目研究的有机薄膜，其形态，吸收和电学性能适合光伏应用。这项研究涉及特拉华大学材料科学与工程专业的Mary Galvin小组和罗切斯特大学化学专业的Lewis Rothberg小组的合作，前者带来了聚合物合成和表征方面的专业知识，后者在测量材料的光学和电学特性并利用它们制造设备方面经验丰富。该项目的目标是满足以下标准的有机薄膜：1)供体和受体部分相隔约10 - 20 nm，大约是有机固体中典型激发态的扩散长度，以促进电荷分离。2)供体和受体材料在空间上被组织成跨越薄膜的双连续网络，以抑制可能导致复合的光生电子和空穴的相遇。3)薄膜厚度相对较小，以适应低电压操作，但薄膜需要尽可能多地吸收光。4)在与太阳光谱相匹配的红光和近红外光谱区，光吸收很强。研究了电子传递受体（n型）和空穴传递给体（p型）共轭聚合物纳米级组织的两种方法。第一种方法依赖于新型嵌段共聚物，共价连接p型和n型嵌段，这些嵌段共聚物将被不相容的侧基结构驱动自发相分离。第二种方法是利用电化学制备的多孔氧化铝模板，在纳米尺度上组织新型盘状支化n型和p型共轭“X”聚合物。这两种策略都允许在最优长度尺度上分离，并对HOMO和LUMO位置进行独立控制，以获得良好的分离效率并匹配接触功函数。高尔文还将设计红色发色团来解决太阳光谱匹配问题，罗斯伯格将实验金属纳米粒子等离子体增强聚合物吸收。这些策略将通过薄膜形态的表征、相关光物理性质的研究和光伏器件的制造来评估。非技术。该项目致力于与电子和光子学技术密切相关的基础材料研究，并有效地将研究与教育结合起来。该项目促进了学生在协作环境中的跨学科教育。迄今为止，PI的合作包括交换和培训攻读化学、材料科学、物理和化学工程博士学位的学生。此外，Galvin和Rothberg都将电子材料纳入研究生和本科生的讲座和实验课程中。pi通过科学博物馆、女孩项目、高中生参与研究以及REU和RET项目参与社区外展活动。这项研究本身是一项很有前途的重要技术，可以帮助世界人口以对环境负责的方式满足其能源需求。

Technical. This project explores new materials and strategies for improved solar cells. Society relies heavily on inexpensive sources of environmentally sound energy and faces a crisis in the years ahead. Photovoltaic devices based on easily processed conjugated organic materials are potential candidates for application as cost-effective, large area solar cells. This project investigates organic films whose morphology, absorptive and electrical properties are suitable for photovoltaic applications. The research involves collaboration between Mary Galvin's group in Materials Science and Engineering at the University of Delaware who bring expertise in polymer synthesis and characterization and Lewis Rothberg's group in Chemistry at the University of Rochester who are experienced in measuring optical and electrical properties of materials and in using them to make devices. The project aims for organic films which satisfy the following criteria: 1) Donor and acceptor moieties are separated by around 10 - 20 nm, approximately the diffusion length for typical excited states in organic solids, to facilitate charge separation. 2) Donor and acceptor materials are spatially organized into bicontinuous networks spanning the film to suppress encounters of photogenerated electrons and holes that might result in recombination. 3) Film thicknesses are relatively small to accommodate low voltage operation but the films need to absorb as much light as possible. 4) Optical absorption is strong in the red and near-infrared spectral regions to match the solar spectrum.Two approaches to nanometer scale organization of electron transporting acceptor ("n-type") and hole transporting donor ("p-type") conjugated polymers will be investigated. The first relies on novel block copolymers with covalently linked p-type and n-type blocks that will be driven to spontaneously phase segregate by incompatible side group architectures. The second relies on nanoscale organization of new discotic-like branched n-type and p-type conjugated "X" polymers using electrochemically produced porous alumina templates. Both strategies allow for separation on the optimal length scale and independent control over HOMO and LUMO positions for good separation efficiency and match to contact work functions. Galvin will also design red chromophores to address solar spectrum match and Rothberg will experiment with metal nanoparticle plasmon-enhancement of the polymer absorption. These strategies will be evaluated by characterization of film morphology, study of relevant photophysical properties, and fabrication of photovoltaic devices. Nontechnical. The project addresses fundamental materials research with strong technological relevance to electronics and photonics, and effectively integrates research and education. The project facilitates interdisciplinary education of students in a collaborative environment. The PI collaborations to date have involved exchange and training of students pursuing Ph.D. degrees in Chemistry, Materials Science, Physics and Chemical Engineering. In addition, Galvin and Rothberg both incorporate electronic materials into the lecture and laboratory curricula at the graduate and undergraduate levels. The PIs participate in community outreach through the Science Museum, girls programs, high school student involvement in research and the REU and RET programs. The research itself is a promising approach to an important technology that may help the world population to meet its energy needs in an environmentally responsible fashion.