Electroactive Organic Materials and Nanoscale Patterning Strategies for Photovoltaic Devices

技术.该项目探索用于改进太阳能电池的新材料和策略。社会严重依赖廉价的无害环境能源，并在未来几年面临危机。基于易于加工的共轭有机材料的光伏器件是作为具有成本效益的大面积太阳能电池应用的潜在候选者。本项目研究有机薄膜的形态，吸收和电气性能适合光伏应用。这项研究涉及特拉华州大学材料科学与工程专业的玛丽高尔文小组与罗切斯特大学化学专业的刘易斯罗斯伯格小组之间的合作，他们在测量材料的光学和电学特性以及使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膜：1）供体和受体部分分离约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组织成跨越膜的双连续网络，以抑制可能导致复合的光生电子和空穴的相遇。 3)膜厚度相对较小以适应低电压操作，但膜需要吸收尽可能多的光。 4)光吸收在红色和近红外光谱区是强的，以匹配太阳光谱。两种方法，电子传输受体（“n型”）和空穴传输供体（“p型”）共轭聚合物的纳米级组织将进行研究。第一种依赖于具有共价连接的p型和n型嵌段的新型嵌段共聚物，所述嵌段共聚物将被不相容的侧基结构驱动以自发地相分离。第二个依赖于新的盘状分支的n-型和p-型共轭的“X”聚合物，使用电化学生产的多孔氧化铝模板的纳米级组织。这两种策略都允许在最佳长度尺度上进行分离，并独立控制HOMO和LUMO位置，以获得良好的分离效率并与接触功函数相匹配。Galvin还将设计红色发色团以解决太阳光谱匹配问题，Rothberg将实验金属纳米颗粒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、相关物理性质的研究和光伏器件的制造来评估。 非技术性的该项目涉及与电子和光子学技术密切相关的基础材料研究，并有效地整合了研究和教育。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养攻读博士学位的学生。化学、材料科学、物理和化学工程学位。此外，高尔文和Rothberg都将电子材料纳入研究生和本科生的讲座和实验室课程。PI通过科学博物馆、女孩方案、高中生参与研究以及REU和RET方案参与社区外展活动。这项研究本身是一种很有希望的方法，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.