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

• Applicant: Professor Dr. Alfred J. Meixner
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2009 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 138845842

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.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1391: Ultrafast Nanooptics
• Participating Person: Professorin Dai Zhang, Ph.D.