On the morphology of polymer-based photovoltaics

We review the morphologies of polymer-based solar cells and the parameters that govern the evolution of the morphologies and describe different approaches to achieve the optimum morphology for a BHJ OPV. While there are some distinct differences, there are also some commonalities. It is evident that morphology and the control of the morphology are important for device performance and, by controlling the thermodynamics, in particular, the interactions of the components, and by controlling kinetic parameters, like the rate of solvent evaporation, crystallization and phase separation, optimized morphologies for a given system can be achieved. While much research has focused on P3HT, it is evident that a clearer understanding of the morphology and the evolution of the morphology in low bad gap polymer systems will increase the efficiency further. While current OPVs are on the verge of breaking the 10% barrier, manipulating and controlling the morphology will still be key for device optimization and, equally important, for the fabrication of these devices in an industrial setting. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012