Effect of blend layer morphology on performance of ZnPc: C60-based photovoltaic cells

Zinc phthalocyanine (ZnPc): fullerene-C-60 (C-60) -based organic photovoltaic (OPV) with high power conversion efficiency (PCE) are fabricated. Homogeneously distributed grains of similar to 40-50 nm are observed for the ZnPc: C-60 blend layer deposited on bare indium-tin oxide (ITO) substrates. In contrast, the blend layer form grains of smaller lateral extensions (similar to 20-30 nm) on 3, 4-polyethylenedioxythiophene: polystyrenesulfonate modified ITO substrates. OPV fabricated on the former substrates show PCE of up to 3.9% that is about twice the PCE (1.9%) obtained for the devices on the latter substrates. This effect can be explained by better transport properties and reduced charge recombination of the blend layer on the bare ITO. (C) 2010 American Institute of Physics. [doi:10.1063/1.3493177]