CAS: Harvesting Electrons From Lower Energy Excited States to Extend Spectral Coverage and Facilitate Multiple Charge Collection Following Singlet Fission on Metal Oxides

在化学结构，动力学机制-化学部B计划的支持下，明尼苏达大学双城分校的Blank和Gladfelter教授以及明尼苏达大学莫里斯分校的Pappenfus教授寻求更深入地了解光如何用于诱导电荷分离，这是将太阳能转化为电能或化学能的关键第一步。除了光伏器件之外，光致电荷转移也是传感器等其他器件的一部分。该项目将专注于使用定义明确的金属氧化物纳米晶体作为探测这种行为的支架。更好地理解如何利用金属氧化物半导体有望有助于开发一系列光电器件并提高此类器件的效率。该项目将直接支持下一代物理/物理有机化学家的培训和教育，包括研究生和本科生，在跨越传统学科界限的化学领域。明尼苏达大学莫里斯分校是一所以本科为主的农村院校，该项目将为莫里斯大学的本科生提供合作研究经验。半导体金属氧化物纳米晶薄膜通常在涉及电荷分离的器件中发挥核心作用。常用的金属氧化物具有导带能量，其对用作敏化剂的分子施加热力学和动力学限制。氧化铟尚未受到太多关注，但它具有巨大的潜力。具有较低能量的导带，它打开了一个新的机会窗口，以获得较低能量的敏化剂状态。原则上，该窗口将允许扩展可以收获的光谱，并提供从敏化剂的较低能量三重态的电荷转移的途径。在这个提议中特别感兴趣的三重态是那些通过单重态裂变产生的三重态。该项目将使用具有窄尺寸分布的纳米晶体的透明溶液相分散体作为定义明确的实验平台来研究敏化剂的激发态动力学和电荷转移。目标是通过在透明金属氧化物表面上的单线态裂变实现、表征和优化电荷倍增，并有可能提高光收集效率。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Structure, Dynamics & Mechanisms-B Program of the Chemistry Division, Professors Blank and Gladfelter from the University of Minnesota-Twin Cities and Professor Pappenfus from the University of Minnesota-Morris seek to build a more thorough understanding of how light can be used to induce separation of charge, a critical first step in the conversion solar energy into electrical or chemical energy. In addition to photovoltaic devices, light-induced charge transfer is part of other devices such as sensors. This project will focus on using well-defined nanocrystals of metal oxides as the scaffold for probing this behavior. A better understanding of how to leverage metal oxide semiconductors is expected to contribute to the development of a range of optoelectronic devices and to improving the efficiency of such devices. This project will directly support the training and education of the next generation of physical/physical organic chemists, including graduate students and undergraduate students, in areas of chemistry that cross the traditional disciplinary boundaries. The University of Minnesota-Morris is a rural, primarily undergraduate institution, and this project will provide undergraduate students at Morris with a collaborative research experience.Nanocrystalline films of semiconducting metal oxides often play a central role in devices that involve the separation of charge. Commonly employed metal oxides have conduction band energies that place thermodynamic and kinetic limitations on the molecules used as sensitizers. Indium oxide has yet to receive much attention, but it has tremendous potential. With a lower energy conduction band, it opens a new window of opportunity to access lower energy sensitizer states. This window would, in principle, allow extension of the spectrum of light that can be harvested and provide access for charge transfer from lower energy triplet states of the sensitizers. The triplet states that are of particular interest in this proposal are those that are generated via singlet fission. This project will use transparent solution phase dispersions of nanocrystals with narrow size distributions as a well-defined experimental platform to investigate the excited state dynamics and charge transfer of the sensitizer. The goal is to realize, characterize and optimize charge multiplication through singlet fission on a transparent metal oxide surface with the potential to increase the efficiency of light harvesting.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.