C 2011 American Chemical Society Aqueous Processing of Low-Band-Gap Polymer Solar Cells Using Roll-to-Roll Methods

queous processing of polymer solar cells presents the ultimate challenge in terms of environmental friendli-ness and has only been reported in a few instances. The approaches to solubilization of the conjugated and active material in water fall in three categories: solubilization through (1) ionic side chains such as sulfonic acid, carboxylic acid, or ammonium, (2) nanoparticle dispersions of hydrophobic polymers in water, or (3) nonionic alcohol and glycol side chains. The latter approach is the most recent and most successful in terms of performance where PCEs of up to 0.7 % have been reached on indium ti