ABSTRACT
To meet the energy demands of the world in the 21st century, it is necessary to develop affordable renewable energy sources. Today, solar cells based on
organic materials and polymers are considered promising alternatives to their inorganic counterparts. Some of the advantages of organic solar cells are their lightweight, mechanical fl exibility, and simple processing as well as easy tunability of chemical properties of the organic materials.1,2
Polymeric solar cells, due to easy solution processing, are especially attractive to harness solar energy in a cost-effective way. They are designed based on the phenomenon of photoinduced electron transfer in organic molecules, which is an intensively investigated topic in physics and chemistry.3 Since the discovery of an effi cient photoinduced electron transfer from conjugated polymers to C60,3 signifi cant efforts are underway to improve the effi ciency of polymer solar cells to the level of practical applications.4-6 Device effi ciencies around 6% have been reported to date,7 which is just below the threshold required for commercial development. This also implies that a signifi cant amount of research is required to bring this technology out from the research labs to the market.
