Inkjet printed solar cell active layers prepared from chlorine-free solvent systems

Organic solar cells are appealing with respect to their inorganic counterparts because the functional layers of these devices can be processed from solution with technologies such as inkjet printing. In order to be able to use inkjet printing on a large scale, hazardous, chlorinated solvents should be avoided when depositing the functional materials. In this work, a novel adapted absorber polymer was blended with fullerene and inkjet printing was used to deposit the blend films. A special emphasis was placed on finding a chlorine-free solvent system which delivers good device performance. A chlorine-free solvent system based on anisole and tetralin delivered efficiencies of 2.7% which compares to 3.5% for active layers that were printed from chlorinated solvents. A coarser phase separation was found with energy filtered transmission electron microscopy plasmon mapping which most likely resulted in the performance differences for the chlorinated and chlorine-free solvent systems.