Solution-Processable Graphene Quantum Dots for Thin-Film Photovoltaics

技术总结该项目由固态和材料化学、电子和光子材料计划支持，将开发具有精确控制结构的可溶液处理的石墨烯量子点(QD)，并研究其用于薄膜光伏的电光性能。我们的目标是利用石墨烯量子点的独特性质，如宽的、可调的吸收光谱、大的消光系数和长的热载流子寿命，来克服溶液处理太阳能电池发展中的一些主要困难。可溶的、定义良好的石墨烯量子点将被合成和研究，以便它们的性能可以被优化以进行能量转换。由于石墨烯在地球上由丰富的元素组成，而且对环境友好，因此拟议的研究可能会产生低成本的太阳能发电，对环境的不利影响最小，从而导致可持续地利用碳进行能源应用。石墨烯量子点是通过逐步溶液化学合成的，因此具有精确的结构和性质控制。我们将研究量子点中的能量弛豫动力学，这是利用吸收的光子能量所必需的过程。此外，染料敏化太阳能电池的吸收光谱、氧化还原电位、电子转移动力学以及它们与金属氧化物的相互作用等性能将得到优化。石墨烯的大小、形状和官能化将以严格控制的方式变化，以便可以识别和理解决定其在光伏设备中性能的参数。本文提出的这项研究是为了创造一种新型的碳材料，这种材料可以用简单的方法加工成高效的薄膜太阳能电池。因为它们很容易获得，而且对环境友好，这种材料可能会导致低成本的太阳能电池，对环境的不利影响最小。拟议工作的成功可能会带来一种可持续的碳能源利用方式，即该项目中使用的碳材料将成为收集阳光并将其转化为电能的活性介质，而不是基于碳的能源(如煤炭)。拟议中的研究将是年轻科学家招募和培训的极好工具，因为它针对的是日益引起学生兴趣的挑战，而且它具有跨学科的性质。例如，研究表明，跨学科的科学项目往往会吸引和留住更多的女学生。通过本科生课堂和外展项目，这项研究将产生传统大学教学无法企及的影响，并提高普通公众的科学素养。

TECHNICALSUMMARYThis project supported by the Solid State and Materials Chemistry and Electronic and Photonic Materials Programs will develop solution-processable graphene quantum dots (QDs) with precisely controlled structures and study their electro-optical properties for thin-film photovoltaics. The goal is to exploit the unique properties of the graphene QDs, such as their broad, tunable absorption spectra, large extinction coefficient, and long hot-carrier lifetimes, to overcome some major difficulties in development of solution-processed solar cells. Soluble, well-defined graphene QDs will be synthesized and investigated so that their properties can be optimized for energy conversion. Since graphenes are made of abundant elements on Earth and are environmentally friendly, the proposed research could result in low-cost solar electricity with minimal adverse environmental impact, and thus lead to sustainable ways of using carbon for energy applications.The graphene QDs are synthesized through stepwise solution chemistry and therefore have precisely controlled structures and properties. The energy relaxation dynamics in the QDs will be investigated, which is an essential process for utilization of the photon energy absorbed. In addition, their properties, such as absorption spectra, redox potentials, electron transfer dynamics, and their interaction with metal oxides, will be optimized for dye-sensitized solar cells. The size, shape, and functionalization of the graphenes will be varied in a tightly controlled way, so that the parameters dictating their performance in the photovoltaic devices can be indentified and understood. NON-TECHNICALSUMMARY The research proposed herein is to create a new type of carbon material that can be processed in simple ways for efficient thin-film solar cells. Because they are readily available and are environmentally friendly, the materials could lead to low-cost solar cells with minimal adverse environmental impact. The success of the proposed work could lead to a sustainable way of using carbon for energy, that is, instead of carbon-based energy sources(like coal) the carbon materials used in this project will be the active media that harvests and converts sunlight to electricity. The proposed research will be an excellent recruiting and training tool for young scientists, because it targets challenges that increasingly draw interest of students, and because of its interdisciplinary nature. For example, studies showed that interdisciplinary science programs tended to attract and retain more female students. Through undergraduate classroom and outreach programs, the research will have impact beyond the reach of traditional university teaching, and improve science literacy of the general public.