Morphology control effects of ternary blended C60 towards high performance thick film organic solar cells

We have fabricated poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3000-di(2-octyldodecyl)- 2,20;50,200;500,2000-quaterthiophen-5,5000-diyl)] PffBT4T-2OD/fullerene (C60)/[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) ternary blend films. The thin films have been characterized by atomic force microscope (AFM) and ultraviolet/visible spectroscopy in order to study the influence of C60 doping on the morphological and optical properties of the active layer. The results show the incorporation of C60 into PffBT4T-2OD : PC71BM thin film improves the photovoltaic characteristics and shows preferable morphology. Furthermore, we demonstrate the addition of C60 can suppress bimolecular recombination and thus enhanced FF. This work illustrates a valuable strategy towards thick film OSCs with high-performances.