Cascade-energy-level alignment based organic photovoltaic cells by utilizing copper phthalocyanine as bipolar carrier transporting layer

We demonstrate a cascade-energy-level alignment based organic photovoltaic cell by using stacking three materials with appropriate energy levels. A cell with a structure of ITO/4, 4′, 4″ -tris [N,(3-methylphenyl)- N -phenylamino]-triphenylamine (m -MTDATA)/copper phthalocyanine (CuPc)/fullerene (C60) /4, 4′ -N, N′ -dicarubreneazolebiphenyl (BCP)/LiF/Al was shown to have a power efficiency enhancement in more than 30% over that of a standard reference cell (ITO/CuPc/ C60 /BCP/LiF/Al), which has only one exciton-dissociation interface. The efficiency improvement was mainly ascribed to the ingenious cascade-energy-level alignment and the application of the bipolar carrier transporting property. © 2009 American Institute of Physics.