Controlling of the interplay between order and disorder by side-chain based statistic block-copolymers for photovoltaics

• Applicants: Privatdozent Dr. Daniel Ayuk Mbi Egbe; Privatdozent Dr. Harald Hoppe; Professorin Dr. Silke Rathgeber
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2008 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 66352344

The goal of the present project is to gain synthetic control over the π−π stacking ability of low band gap poly(p-arylene-ethynylene)-alt-poly(p-arylene-vinylene)s based copolymers. This is attained through grafting of linear and/or branched alkoxy side chains. Special emphasis will be laid on side chain based statistic block-copolymers consisting of sequences of linear as well as branched side chains randomly distributed within the conjugated backbone. The aim is to establish a correlation between the π−π-stacking ability of the polymers, the electronic and photophysical properties of the polymers and polymer-fullerene photo-active layers, the nanoscale morphology of the latter up to the photovoltaic performance of the solar cells. The nano-scale phase separation in the active layers will also be tuned by using mixture of sol-vents for film preparation as well as by changing the solubility of different fullerene derivatives. The morphology will be investigated over a broad length scale range by atomic force microscopy, scattering methods and optical microscopy. We will implement new spatially- and time-resolved scattering methods which allow monitoring morphological changes such as self-assembly and phase separation during real printing and annealing processes online. In order to gain knowledge about the long-term stability of the materials we will perform photo-degradation studies and solar cell lifetime investigations.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1355: Elementary Processes of Organic Photovoltaics
• International Connection: Austria