SusChEM: Next-Generation Dye-Sensitizers: Beyond the Shockley-Queisser Limit

技术描述：来自植物的有机染料增敏剂正在被研究，因为当用作二氧化钛纳米粒子的增敏剂时，它们有可能为每个入射光子提供两个或更多的电荷载体。该项目的目标是确定太阳能转换效率超过31%限制的设备的分子基础。先前发现甜菜素植物色素在染料敏化太阳能电池中光子转化为电子的产量很高，首席研究员和她的学生利用光谱学方法揭示载子增殖的机理细节，以及二氧化钛上甜菜素染料增强光捕获（光谱展宽）的分子基础。光谱电化学测量和时间分辨光谱测量被应用于确定同时发生双电子氧化、电流倍增和单线态裂变的可能性。利用共振拉曼光谱研究了非均相染料结合、共敏化和染料聚集在二氧化钛上增强甜菜素颜料的光收获作用。非技术描述：这项研究的结果揭示了如何在各种光伏设备中提高太阳能转换的效率，包括那些可能比当前一代太阳能电池更便宜和更环保的设备，从而使社会受益。更广泛的影响包括培养研究生和本科生从事促进可持续能源生产的研究。首席研究员实验室的研究生接受光谱学、电化学和纳米技术方面的技术培训，并参与了两个推广项目，使初高中学生对科学和替代能源产生兴趣。“想象明天”竞赛在未来的科学家和教师之间建立了联系，同时允许双方展示他们在替代能源方面的研究成果。研究生们正在为7-12年级的学生设计一个美洲狮探索夏令营，让营员们在学习太阳能转换的同时为这个项目做出贡献。

Technical Description: Organic dye sensitizers derived from plants are being investigated for their potential to provide two or more charge carriers per incident photon when used as sensitizers of titanium dioxide nanoparticles. The goal of the project is to determine the molecular basis for devices in which the efficiency of solar-energy conversion can exceed the 31% limit. Working with betalain plant pigments previously found to give high yields for converting photons to electrons in dye-sensitized solar cells, the principal investigator and her students use spectroscopic methods to reveal the mechanistic details of carrier multiplication and the molecular basis for enhanced light-harvesting (spectral broadening) of betalain dyes on titanium dioxide. Spectroelectrochemical measurements and time-resolved spectroscopy measurements are applied to determine the possibility of simultaneous two-electron oxidation, current multiplication, and singlet fission. The role of heterogeneous dye binding, co-sensitization and dye-aggregation in enhancing the light-harvesting of betalain pigments on titanium dioxide is examined using resonance Raman spectroscopy of purified dyes and dye-cocktails adsorbed on shape-tailored semiconductor nanoparticles.Non-technical Description: Results from this research benefit society by revealing how the efficiency of solar-energy conversion can be improved in a variety of photovoltaic devices, including those that are potentially cheaper and more environmentally friendly than current-generation solar cells. Broader impacts include the training of graduate and undergraduate students in research that fosters sustainable energy generation. Graduate students in the principal investigator's lab receive technological training in spectroscopy, electrochemistry and nanotechnology and contribute to two outreach programs that engender excitement about science and alternative energy in middle-school and high-school students. The Imagine Tomorrow competition builds relationships between prospective future scientists and faculty, while allowing both to showcase the results of their research in alternative energy. Graduate students are designing a Cougar Quest summer enrichment camp for Grades 7-12, which will allow campers to contribute to the project while learning about solar energy conversion.