Enhanced efficiency in organic photovoltaic cells using engineered plasmonic nanostructures

使用工程等离子体纳米结构提高有机光伏电池的效率

• 批准号: 1067681
• 负责人: Sang-Hyun Oh
• 金额: $ 30万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1067681&HistoricalAwards=false
• 关键词: Enhanced; efficiency; organic; photovoltaic; cells

Institution: University of Minnesota-Twin CitiesTitle: Enhanced efficiency in organic photovoltaic cells using engineered plasmonic nanostructuresIntellectual MeritOrganic photovoltaic cells (OPVs) have the potential to redefine the cost of solar energy conversion. Organic semiconductors are attractive due to their compatibility with high throughput processing methods, but demonstrated power conversion efficiencies are only around 7%. The proposed research outlines a new approach to overcome the low absorption efficiency typical in OPVs by exploiting surface plasmons in nanostructured metallic electrodes. Since absorption in OPV materials leads to exciton formation, photocurrent generation requires the dissociation of excitons into their constituent charge carriers. This process usually occurs at a hetero-junction between electron donating (D) and accepting (A) materials. The challenge lies in the fact that the exciton diffusion length is typically shorter than the optical absorption length, necessitating the use of thin active layers to efficiently collect and dissociate excitons. This work integrates thin film OPVs with plasmonic electrodes, permitting sub-wavelength confinement and resonant enhancement of the optical field, to increase the absorption and power conversion efficiencies. The combination of a thin OPV with engineered plasmonic electrodes offers the potential for a high level of tunability and control over the exciton-plasmon coupling to realize high efficiency. In the proposed research, novel architectures that offer optical field enhancement from nanostructured plasmonic electrodes will be introduced to maximize optical absorption in thin OPVs and permit the efficient harvesting of excitons and charge carriers. Extensive computational modeling will be performed to identify optimal design rules for plasmonic OPVs. The use of continuous, nanopatterned metal films is attractive, since the field enhancement is longer range (~200 nm) compared with metallic nanoparticles, enhancing absorption throughout the active OPV layers. Furthermore, these continuous films can concurrently function as electrodes, which is not possible with metallic nanoparticles. For high-throughput fabrication of plasmonic electrodes, a template-stripping method will be used. Using mature silicon fabrication technology, a variety of nano-patterned templates will be fabricated. A metal film deposited on the template will form a smooth surface at the interface, which it can be peeled off of the substrate using an elastomeric stamp and directly transferred to the top of a completed OPV cell using cold welding. This scheme will provide unprecedented flexibility in the fabrication of plasmonic OPVs, since the top and bottom electrodes can be independently nano-patterned with high throughput over large areas. The OPVs proposed in this work will also utilize graded donor-acceptor heterojunctions (GHJs). The use of a GHJ is attractive because it balances the need for efficient exciton diffusion (large interface area) with efficient charge collection (graded pathways for transport). The growth of GHJs is also tunable, enabling a range of compositions through which to examine how the design of plasmonic OPVs is impacted by the spatial D-A composition.Broader ImpactsGraduate students associated with this project will acquire an interdisciplinary spectrum of knowledge in nanofabrication, plasmonics, and molecular photophysics in the context of organic photovoltaic devices for renewable energy. Existing undergraduate research opportunities will be enhanced through continuing relationships with the University of Minnesota UROP program and the NSF REU program. For K-12 education, multiple high school researchers will be hosted and mentored in the PIs laboratory during the summer through the Summer Research Cluster in Renewable Energy program. These activities will be complemented by plans to disseminate results from the proposed work to industry via on-campus workshops and annual hands-on lab short courses for industry participants. Finally, ?Sit with a Scientist? sessions at the Science Museum of Minnesota will be organized through the proposed outreach plan during the one week-long NanoDays event in April of each year.

机构：明尼苏达大学双城分校标题：使用工程等离子体纳米结构提高有机光伏电池的效率智力优点有机光伏电池（OPV）有可能重新定义太阳能转换的成本。有机半导体因其与高通量处理方法的兼容性而颇具吸引力，但已证明的功率转换效率仅为 7% 左右。拟议的研究概述了一种新方法，通过利用纳米结构金属电极中的表面等离子体来克服 OPV 中典型的低吸收效率。 由于 OPV 材料中的吸收导致激子形成，因此光电流的产生需要激子解离为其组成的电荷载流子。 该过程通常发生在给电子 (D) 和受电子 (A) 材料之间的异质结处。 挑战在于激子扩散长度通常比光学吸收长度短，因此需要使用薄有源层来有效收集和解离激子。这项工作将薄膜 OPV 与等离子体电极集成在一起，允许亚波长限制和光场共振增强，以提高吸收和功率转换效率。 薄 OPV 与工程等离子体电极的结合提供了对激子-等离子体耦合的高水平可调性和控制的潜力，以实现高效率。 在拟议的研究中，将引入通过纳米结构等离子体电极提供光场增强的新颖架构，以最大限度地提高薄 OPV 中的光吸收，并允许有效收集激子和电荷载流子。 将进行广泛的计算建模以确定等离激元 OPV 的最佳设计规则。 使用连续的纳米图案金属薄膜很有吸引力，因为与金属纳米颗粒相比，场增强的范围更长（~200 nm），从而增强了整个活性 OPV 层的吸收。 此外，这些连续薄膜可以同时充当电极，这是金属纳米粒子不可能实现的。 对于等离子体电极的高通量制造，将使用模板剥离方法。 利用成熟的硅制造技术，可以制造各种纳米图案模板。 沉积在模板上的金属膜将在界面处形成光滑的表面，可以使用弹性体印模将其从基板上剥离，并使用冷焊直接转移到完整 OPV 电池的顶部。该方案将为等离子体 OPV 的制造提供前所未有的灵活性，因为顶部和底部电极可以独立地进行纳米图案化，并且在大面积上具有高通量。这项工作中提出的 OPV 还将利用分级供体-受体异质结 (GHJ)。 GHJ 的使用很有吸引力，因为它平衡了有效激子扩散（大界面面积）和有效电荷收集（分级传输路径）的需求。 GHJ 的生长也是可调的，从而能够形成一系列成分，通过这些成分来检查空间 D-A 成分如何影响等离激元 OPV 的设计。更广泛的影响与该项目相关的研究生将获得纳米制造、等离激元学、以及可再生能源有机光伏器件背景下的分子光物理学。 通过与明尼苏达大学 UROP 项目和 NSF REU 项目的持续合作，现有的本科生研究机会将得到加强。 对于 K-12 教育，夏季期间，将通过可再生能源夏季研究集群项目在 PI 实验室接待和指导多名高中研究人员。 这些活动将辅以计划，通过校园研讨会和为行业参与者举办的年度实践实验室短期课程，向行业传播拟议工作的结果。 最后，“与科学家坐在一起？”明尼苏达科学博物馆的会议将通过每年 4 月为期一周的 NanoDays 活动期间拟议的外展计划进行组织。