Humankind is in the midst of a massive drive to harness solar energy to power our homes, gadgets, and industry. Plastic solar cells, based on blends of conducting organic polymers, are of interest for making lightweight and cheap solar cells. The problem with these kinds of solar cells is that their solar power efficiencies are very closely related to the way the different types of materials mix and crystalize in thin films. This means complex and careful processing is usually needed to make efficient polymer solar cells.