Ultrafast Spectroscopy and Microscopy of Exciton Dynamics in Hybrid Organic solar cell blend film/ Plasmonic Systems on the Nanometer Scale

本项目的主要目标是研究由等离子体纳米粒子和有机半导体太阳能电池混合薄膜组成的纳米光学系统的超快激子动力学，在纳米尺度上具有空间和光学分辨率。这一目标是基于我们在上一个资助期所取得的成果，即我们将抛物镜辅助共聚焦和尖端增强近场光学显微镜与超快激光光谱学相结合来研究有机太阳能电池薄膜中的激子动力学。在这一资助期内的新成果是直接将等离子体纳米系统（金属颗粒和金属结构）添加到太阳能电池混合膜中，这一技术最近在提高光伏设备效率方面得到了突出的应用。作为模型系统，我们将使用两种突出的有机太阳能电池混合物P3HT/PCBM和pcpdbt /PCBM，它们形成所需的体异质结，平均畴尺寸从5纳米到几十纳米不等。具有不同等离子体共振的等离子体金属纳米颗粒，如球体或棒状（可选择光刻制造或蒸发纳米结构）将被集成到太阳能电池混合物中。我们将研究等离子体纳米粒子的非线性激发和激子生成的增强或猝灭以及杂化系统中的激子寿命。结合超快尖端增强近场光学显微镜，我们将在单畴和单纳米粒子水平上成像混合纳米光学系统中局部膜形态和等离子体纳米粒子相关的激子产生和激子寿命变化。通过这个项目，我们将为超快纳米光学做出贡献，对具有高空间、光学和时间分辨率的金属/半导体混合系统中的超快动力学有一个紧凑的理解。所获得的基础知识可以直接转移到等离子体有机光伏领域，在那里可以科学地解决等离子体纳米粒子与分子量子系统耦合的基本问题，如激子增强和猝灭、电子转移等。

The main goal of this project is to study ultrafast exciton dynamics in hybrid nano-optical systems consisting of plasmonic nano-particles and organic semiconductor solar cell blend film with spatial and optical resolutions at nanometer scales. This goal is based on the achievements in the last funding period which we have focused on combining parabolic mirror assisted confocal and tip-enhanced near field optical microscopy with ultrafast laser spectroscopy to study exciton dynamics in organic solar cell film. New in this funding period is the addition of plasmonic nano-systems (metallic particles and metallic structures) directly to the solar cell blend films, which has been highlighted recently for efficiency-improved photovoltaic devices1. As model systems we will use two prominent organic solar cell blends P3HT/PCBM and PCPDTBT/PCBM, which form desired bulk heterojunctions with mean domain sizes ranging from 5 nm to several tens of nanometers. Plasmonic metallic nanoparticles such as spheres or rods (alternatively lithographically fabricated or evaporated nanostructures) with different plasmon resonances will be integrated into the solar cell blends. We will investigate the nonlinear excitations and the enhancement or quenching of the exciton generations by the plasmonic nanoparticles and the exciton lifetime in the hybrid system. Combining with ultrafast tip-enhanced near-field optical microscopy, we will image at single domain and single nanoparticle level the local film morphology and plasmonic nanoparticle related exciton generation and exciton lifetime variations in the hybrid nanooptics systems. With this project we would contribute to the ultrafast nanooptics a compact understanding of ultrafast dynamics in metal/semiconductor hybrid systems with high spatial, optical and tempo-resolutions. The fundamental knowledge obtained could be directly transferred to the field of plasmonic organic photovoltaic, where essential issues concerning the coupling of a plasmonic nano-particle with a molecular quantum system such as exciton enhancement and quenching, electron transfer etc. can be scientifically addressed.