Renewal: Overcoming Energy Loss in Organic Bulk Heterojunctions

非技术性描述。太阳能技术正越来越多地在美国各地以远低于化石燃料的成本提供能源。简而言之，太阳能正在兑现其作为低成本、清洁和可再生能源的承诺。然而，太阳能解决方案在很大程度上是基于硅的，这远远不是一个最佳的解决方案。新的解决方案必须以让太阳能无处不在的目标为目标，帮助满足我们日益增长的能源需求。其中包括太阳能发电窗和建筑集成光伏，以及在非常弱的光线下运行的设备，以清除浪费的照明电力。这是一个紧迫而根本性的技术挑战。最近，潜在的低成本有机太阳能电池的效率已经大幅提高到19%以上，接近硅电池的效率。该项目旨在确定有机太阳能电池的最终功率转换效率。研究人员将用最先进的光学光谱学研究新的有机材料，以了解限制有机太阳能电池效率的发电机制。从这些研究中得出的原理可以提供分子设计规则，并指导有机太阳能电池朝着其理论效率极限~25%的方向发展。该项目通过对研究生和本科生进行材料设计、合成和表征方面的教育，以及设备工程和科学交流，支持对多样化劳动力的培训。PIS将通过密歇根大学的多样性、公平性和包容性努力，在STEM领域招收和留住多样化的下一代学生，包括向代表不足的群体进行外联，并主办一次本科生物理学女性会议。该项目的主要目标是通过改进基于量子力学模型的材料和器件设计策略来了解和改进有机光伏(OPV)器件。在成熟的成熟太阳能技术效率较低的情况下，充电光伏发电过程中显著减少的能量损失最终可能提供一条通往超低成本太阳能发电的途径。除了太阳能收集，这些系统还为在原子水平上进行电荷和能量传输的工程材料开辟了新的途径，并为它们在特殊距离上的光发射、能量和电荷转移等应用中的开发开辟了新的途径，甚至可能导致电子技术远远超出目前的限制。该项目将研究人员在OPV材料、设计和表征方面的广泛专业知识与最先进和新兴的多维光谱相结合，以了解目前限制单结有机太阳能电池器件效率的能量损失机制。从这些基础研究中得出的原理提供了分子设计规则，以指导电池效率的提高，使其热力学极限达到~25%。这项工作极大地扩展了探测OPV的光谱工具箱，为理解电荷产生和伴随的能量损失的机制提供了变革性的机会。这项研究有以下主要目标：(I)对控制有机异质结(HJS)电荷产生和能量损失的机制有一个基本的了解，以将太阳能到电力的转换效率提高到接近热力学极限；(Ii)使用多维光谱绘制HJ电荷的整个光生过程图，以探索电荷产生的机制和能量损失的来源；(Iii)利用独特的光收集体系结构中的超强耦合来实现近零能量损失的激子-偏振子传输。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Description. Solar technologies are increasingly providing energy across the US at costs well below even that of fossil fuels. In short, solar energy is delivering on its promise as a source of low cost, clean and renewable energy. However, solar solutions have largely been based on silicon, which is far from an optimal solution. New solutions must have the objective of making solar power ubiquitous, helping to fulfill our ever-expanding energy needs. These include solar power generating windows and building-integrated photovoltaics as well as devices that operate at very low light levels to scavenge waste illumination power. This is an urgent and fundamental technological challenge. Recently, there have been dramatic increases in the efficiency of potentially low-cost organic solar cells to over 19%, approaching that of silicon cells. This project is directed at determining the ultimate power conversion efficiency of organic solar cells. The investigators will study new organic materials with state-of-the-art optical spectroscopy to understand the power generating mechanisms that limit the efficiency of organic solar cells. The principles derived from these studies can provide molecular design rules and guide the improvement of organic solar cells towards their theoretical limit of ~25% efficiency. The project supports training of a diverse workforce through the education of graduate and undergraduate students in materials design, synthesis, and characterization, coupled with device engineering and scientific communication. The PIs will recruit and retain a diverse next generation of students in STEM fields through diversity, equity and inclusion efforts at the University of Michigan, including outreach to underrepresented groups and hosting a Conference for Undergraduate Women in Physics.Technical Description. The primary goal of this project is to understand and improve organic photovoltaic (OPV) devices through improved materials and device design strategies based on quantum mechanical models. Dramatically reduced energy losses in the charge photogeneration process may ultimately provide a pathway towards ultralow cost solar power in situations where established, mature solar technologies are less effective. Beyond solar energy harvesting, these systems open new avenues for engineering materials for charge and energy transport at the atomistic level, and for their exploitation in applications as light emission, energy and charge transfer over exceptional distances, and may even result in extending electronic technology well beyond its current limits. This project combines the investigators’ extensive expertise in OPV materials, design and characterization with state-of-the-art and emerging multidimensional spectroscopies to understand the energy loss mechanisms that currently limit single junction organic solar cell device efficiencies. The principles derived from these fundamental studies provide molecular design rules to guide the improvement of cell efficiencies towards their thermodynamic limit of ~25%. The work significantly expands the spectroscopic toolbox for probing OPVs, providing transformative opportunities for understanding the mechanisms of charge generation and concomitant energy losses. The research has the following primary goals: (i) Gain a fundamental understanding of the mechanisms governing charge generation and energy loss at organic heterojunctions (HJs) to increase the solar-to-electrical power conversion efficiency to near the thermodynamic limit; (ii) Map the complete HJ charge photogeneration process using multidimensional spectroscopy to probe the mechanisms of charge generation and the origins of energy loss; (iii) Exploit ultrastrong coupling in unique light harvesting architectures to realize exciton-polariton transfer with near-zero energy loss.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.