Solution-Processable Graphene Quantum Dots for Thin-Film Photovoltaics

该项目由固态与材料化学和电子与光子材料项目支持，将开发具有精确控制结构的溶液可加工石墨烯量子点（QDs），并研究其用于薄膜光伏的电光特性。其目标是利用石墨烯量子点的独特特性，如其广泛、可调谐的吸收光谱、大消光系数和长热载子寿命，来克服溶液处理太阳能电池发展中的一些主要困难。将合成和研究可溶的、定义良好的石墨烯量子点，以便优化其性能以进行能量转换。由于石墨烯是由地球上丰富的元素构成的，并且对环境友好，因此拟议的研究可能会产生低成本的太阳能电力，对环境的不利影响最小，从而导致将碳用于能源应用的可持续方式。石墨烯量子点是通过逐步溶液化学合成的，因此具有精确控制的结构和性质。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的必要过程。此外，它们的特性，如吸收光谱、氧化还原电位、电子传递动力学以及它们与金属氧化物的相互作用，将被优化用于染料敏化太阳能电池。石墨烯的尺寸、形状和功能化将以严格控制的方式变化，因此决定其在光伏器件中性能的参数可以被识别和理解。本文提出的研究是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，这种材料可以制造出低成本的太阳能电池，对环境的不利影响最小。这项工作的成功可能会导致使用碳作为能源的可持续方式，也就是说，代替碳基能源（如煤），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。拟议的研究将是一个很好的招募和培训年轻科学家的工具，因为它针对的挑战越来越吸引学生的兴趣，而且因为它的跨学科性质。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。通过本科课堂和外展项目，研究将产生传统大学教学无法达到的影响，并提高公众的科学素养。

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.