Sequent spray deposition of secondary solvent for efficient polymer solar cells

The spray process is compatible with the roll-to-roll process, which has the highest productivity and the lowest costs among the developed processing techniques. In this study, we demonstrated a technique involving the spraying of a secondary solvent after the formation of an active layer, by using a spray process with a relatively lowboiling- point solution. With this technique, we obtained the much smoother surface topography and more ordered bulk heterojunction morphology through enhanced self-organization of the composite materials. Consequently, the device with additionally sprayed high-boiling-point solvent allowed to achieve fill factor (FF) and power conversion efficiency (PCE) values as high as 67% and 3.76%, respectively. [Figure not available: see fulltext.]