Fully organic dye based tandem photovoltaic cells

We report on fabrication and testing of an all-organic-dye-based photovoltaic cell using a tandem architecture. Proceeding from the well-known concept of stacked molecular p/n-junctions, we developed a device with two stacked Schottky barrier subcells. Both subcells are based on p-type organic dyes: boron subphthalocyanine chloride (SubPc/Al barrier) for the front cell and vanadyl phthalocyanine (PcVO/Mg:Ag barrier) for the back one. These two dyes are complementary to each other in terms of optical activity, so the newly formed tandem cell absorbs a broad range of wavelengths from 300 to 1100 nm. Introduction of ultrathin intermediate layer of a third conductive dye, vanadyl naphthalocyanine (NcVO), at the Al/PcVO interface makes possible a serial connection of subcells, resulting in summation of open circuit voltages.