The development of high-efficiency plastic solar cells is rapidly accelerating as the need for economically viable alternative energy sources becomes evident. Polymer-based bulk-heterojunction (BHJ) solar cells are attractive in that they. can be coated from solution onto flexible substrates by possible. and thus inexpensive large-volume manufacturing should be possible. Further, the inherent flexibility of the polymeric materials combined with thin photovoltaic active layers results in devices that can be adapted to variety of unique aesthetics and form factors. Recent advances in key relationships between thin-film casting methods, bulk-heterojunction morphology, and device performance have occurred in tandem with the synthesis of novel polymer semiconductors that possess increased optical-absorption breadth and optoelectronic performance. This Research News article highlights a few techniques developed to optimize the BHJ nanomorphology and performance of solar cells fabricated by various solution-processing methods.