Project R-4316

Influence of molecular weight and polydispersity on the properties of printable organic solar cells based on new generation push-pull polymers (Research)

Photovoltaic cells can deliver a remarkable contribution to the production of sustainable energy. Organic solar cells (OSC), comprised out of a blend of polymer and fullerene molecules, differentiate themselves from the classic silicon technology because they can be made flexible, roll to roll compatible and offer very appealing aesthetics. The research towards OSC has had an incredible boost during the last decade, leading to a lot of progress. However high efficiencies combined with long lifetimes and reproducibility still remain a challenge which needs to tackled if this technology wants to become market ready. Molecular weight (MW) and polydispersity (PD) have a major influence on the mechanical and electrical properties of conjugated polymers. At this moment there isn't a clear picture of the optimal molecular weight range or even what the role of the molecular weight is. The effect of MW and PD on photo-physical processes, e.g. charge generation and recombination or the stability of push-pull based solar cells, has hardly been studied. The goal of this project is to better understand the influence of MW and PD on the electro-optical properties and the stability of solution processable OSC's, leading to new insights on the nanomorphology, charge generation, recombination and transport. These insights can lead to major improvements in efficiency, stability and reproducibility. This project consists out of four work stations. In the first phase the polymers will be separated according to MW and PD with an emphasis on purity, crystallization and thermal properties. These parameters will in a second phase be linked to optical, electrical and morphological features of thin films. The knowledge gained throughout the first two stages will then be adapted in the third work station to complete devices. These devices will be aged in the fourth and final work station to obtain more knowledge about their intrinsic lifetime. The combination of the knowledge gained during all these work stations will lead to a better understanding of fundamental processes and improvements of the conversion efficiency, stability and reproducibility of printable organic solar cells.

01 January 2013 - 31 December 2016