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

Zinc phthalocyanine (ZnPc): fullerene-C60 (C60)-based organic photovoltaic (OPV) with high power conversion efficiency (PCE) are fabricated. Homogeneously distributed grains of ∼40–50 nm are observed for the ZnPc:C60 blend layer deposited on bare indium-tin oxide (ITO) substrates. In contrast, the blend layer form grains of smaller lateral extensions (∼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.