On the Role of Bathocuproine in Organic Photovoltaic Cells

The effect of bathocuproine (BCP) on the optical and electrical properties of organic planar heterounction photovoltaic cells is quantified by current-voltage characterization under 1 sun AM 1.5D simulated solar illumination and spectral response at short-circuit conditions. By inserting a 10 nm BCP layer in an indium tin oxide (ITO)/subphthalocyanine (SubPc)/buckminsterfullerene (C 60 )/BCP/Al thin film structure, an increase in power-conversion efficiency from 0.05 to 3.0 %Ct is observed, mostly reflected in the enhanced open-circuit voltage up to 920mV. Furthermore, the incorporation of a 10-nm BCP layer in an ITO/C 60 /BCP/Al structure leads to an increase in built-in potential from 250 to 850 mV, as demonstrated by electroabsorption. It is argued that BCP passivates C 60 such that in 10-nm layer provides a sufficient buffer layer that prohibits Al contacting the C 60 where it would otherwise create donor states.