Efficient polymer tandem modules and solar cells by doctor blading

Abstract

Polymeric tandem solar cells and modules with commercially available absorber materials are investigated. The optimized tandem cells with nanoparticle-based ZnO recombination layer show good performance with PCDTBT and Si-PCPDTBT as two complementary absorber polymers. Power conversion efficiencies of up to 6.9% are achieved with spin coated reference cells. All layers of the tandem stack (except for the electrodes) are deposited from solution. Furthermore, we could prepare efficient tandem cells with efficiencies up to 6.3% by doctor blading in ambient atmosphere, demonstrating an industrially relevant deposition technique more suitable than the commonly used spin coating. First tandem modules consisting of 3 or 5 cells stripes and interconnected in series have been prepared. Encouraging module efficiencies of 5.2% (1.3 cm² active area) and 4.7% (2.1 cm² active area) are demonstrated with nearly no losses in open circuit voltage compared to the individual tandem cells. Hence, the described device architecture as well as the serial interconnection indicates the high potential for an industrial fabrication of polymer tandem modules.