Morphological and Optical Engineering for High-Performance Polymer Solar Cells.

We demonstrate morphological and optical engineering by using processing additives and optical spacers for polymer solar cells. Among various processing additives, introduction of diphenyl ether (DPE) into the active layer results in the smoothest surface roughness with uniform and well-distributed donor/acceptor domains, and the device with DPE shows the highest device efficiency of 10.22% due to enhanced charge collection efficiency and minimized recombination loss. Additional ZnO optical spacers on the active layer controls the distribution of the electric field in the whole device and enhances the light absorption within the active layer, thereby improving device efficiency up to 10.81%.