Highly efficient organic tandem solar cells using an improved connecting architecture

Tandem solar cells based on the combination of a poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl-C61-butyric acid methyl ester and a copper phthalocyanine:fullerene subcell are reported. By using a highly transparent, high-work function WO3 layer as part of the interconnecting system for the two subcells, the authors demonstrate stacked devices with power conversion efficiencies as high as 4.6%. The efficiency of the stacked devices is close to the sum of the efficiencies of the individual subcells.