Hole-transport limited S-shaped I-V curves in planar heterojunction organic photovoltaic cells

Current-voltage (I-V) characteristics of planar heterojunction organic photovoltaic cells based on N',N'-Di-[(1-naphthyl)-N',N'-diphenyl]-1,1'-biphenyl)-4,4'-diamine (NPB) and C(60) are investigated. Through variation of the layer thickness and composition, specifically chemical doping NPB with MoO(x), we show that the hole-transport limitation in the NPB layer is the determining factor in shaping the I-V characteristics of NPB/C(60) cells. (C) 2011 American Institute of Physics. [doi:10.1063/1.3664406]