The role of mesoscopic PCBM crystallites in solvent vapor annealed copolymer solar cells.

摘要: Solution processable methanofullerene-based solar cells are the most widely studied class of organic photovoltaics (OPVs). The evolution electronic properties with solvent vapor annealing (SVA) in polyfluorene-copolymer and [6,6]phenyl-C61-butyric acid methyl ester (PCBM) blended OPVs is using various scanning probe techniques: light beam induced current spectroscopy (LBIC), conductive atomic force microscopy (c-AFM), photoconductive AFM (pc-AFM). We demonstrate that SVA improves power conversion efficiency by 40% while forming mesoscopic PCBM crystallites a ∼3 nm copolymer-rich overlayer at cathode interface. find large created during do not directly improve local performance device, but instead attribute improvement to ripened blend morphology an increase hole mobility copolymer comparison unannealed blend. PCBM-rich aggregates act as sink for excess PCBM, although PC...