Imaging charge recombination dynamics in organic semiconductor films

有机半导体薄膜中的电荷复合动力学成像

• 批准号: 2113994
• 负责人: John Marohn
• 金额: $ 59.26万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2113994&HistoricalAwards=false
• 关键词: Imaging; charge; recombination; dynamics; organic

NON-TECHNICAL SUMMARY: Our economy requires energy to run. Sunlight is a free and essentially limitless source of energy. To exploit this energy source, economical solar cells that can convert sunlight into electrical current and voltage are needed. Existing silicon solar cells are too expensive to create, pattern, and install on a massive scale. Solar cells made from plastics and small molecules, on the other hand, can potentially be as inexpensive as paint to create and as easy as newsprint to pattern at high speed. Plastic/molecular solar cells are being intensely studied worldwide, but how these complex materials convert light to electricity remains a puzzle. With this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, Professor John Marohn and his research group at Cornell University will develop methods for watching how electrical charges in a film activated by sunlight move and relax. The research team will utlizie a specialized microscope which enables the observation of charges moving distances of nanometers (one billionth of a meter) on the timescale of nanoseconds (one billionth of a second). By allowing the observation of charge motion at the molecular level, it is expected that these measurements will significantly advance our understanding of how plastic/molecular solar cell materials convert light into electricity. This research will open new ways to study semiconductor chips and batteries, two growth technologies central to our economy. Researchers funded by this project will develop virtual high-school science experiments on the physics of waves suitable for both in-person and remote learning.TECHNICAL SUMMARY: In the best organic photovoltaic materials, the photocarrier recombination time is anomalously long. If this anomalous behavior could be understood then it could be exploited to improve the open-circuit voltage and current of organic solar cells. This project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, will study charge generation and recombination in organic donor/acceptor (D/A) blends at nanoscale spatial resolution and nanosecond temporal resolution. Proposed experiments include scanning Kelvin probe force microscopy, measuring local electrostatic potential and electric field; broadband local dielectric spectroscopy, measuring local steady-state conductivity and energetic disorder; and "phase-kick" electric force microscopy (pk-EFM), measuring transient conductivity. Charge mobility will be studied in single-component films by simultaneously measuring device current and local electric field. Charge recombination transients in D/A blends prepared on both insulating and metallic substrates will be recorded using pk-EFM and compared to bulk time-resolved microwave conductivity measurements. The drift and diffusion of photogenerated charges in inhomogeneous D/A blends will be observed stroboscopically via pk-EFM. Films comprised of polymer donors with both fullerene and non-fullerene acceptors will be examined. It is expected that the microscopic material parameters gleaned from these measurements will enable the rigorous testing of charge-recombination hypotheses.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.

非技术摘要：我们的经济需要能源运行。阳光是免费的，本质上无限的能源来源。为了利用这种能源，需要将阳光转化为电流和电压的经济太阳能电池。现有的硅太阳能电池太贵了，无法创建，模式和安装大规模。另一方面，由塑料和小分子制成的太阳能电池可能与油漆一样廉价，并且可以像高速的新闻报道一样容易创建。塑料/分子太阳能电池正在全球范围内进行深入研究，但是这些复杂的材料如何将光转换为电能仍然是一个难题。在材料研究部的固态和材料化学计划的支持下，约翰·马罗恩（John Marohn）及其研究小组的康奈尔大学（Cornell University）研究小组将开发出观察Sunlight Move and Halwiss激活的电影中电荷的方法。研究小组将占用专门的显微镜，使观察纳米秒（十亿秒的十亿秒）在纳米秒的时间范围内移动纳米（十亿米）的指控。通过允许在分子水平上观察电荷运动，预计这些测量值将显着提高我们对塑料/分子太阳能电池材料如何将光转化为电能的理解。这项研究将开辟新的方法来研究半导体芯片和电池，这是我们经济中心的两种增长技术。该项目资助的研究人员将开发有关适合面对面和远程学习的波的物理学的虚拟高中科学实验。技术摘要：在最佳的有机光伏材料中，光载体重组时间是无意的。如果可以理解这种异常行为，则可以利用它来改善有机太阳能电池的开路电压和电流。该项目在材料研究部的固态和材料化学计划的支持下，将研究有机供体/受体（D/A）在纳米级空间分辨率和纳秒时间分辨率的有机供体/受体（D/A）中的重组。建议的实验包括扫描开尔文探针力显微镜，测量局部静电电位和电场。宽带局部介电光谱，测量局部稳态电导率和能量障碍；和“相踢”电力显微镜（PK-EFM），测量瞬态电导率。通过同时测量设备电流和局部电场，将在单组分膜中研究电荷迁移率。在绝缘和金属底物上制备的D/A混合物中的电荷重组瞬变将使用PK-EFM记录，并将其与大量时间分辨的微波电导率测量值进行比较。将通过PK-EFM观察到频镜观察到光生的电荷在不均匀D/A混合物中的漂移和扩散。将检查由富勒烯和非富勒烯受体的聚合物供体组成的电影。预计从这些测量结果中收集的微观材料参数将能够对电荷重组假设进行严格的测试。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的智力优点和更广泛影响的评估标准来评估的支持。