Organic tandem solar cells comprising polymer and small-molecule subcells

In this work the authors report monolithic organic tandem solar cells. The front cell is fabricated from a blend of poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl C-61-butyric acid methyl ester while a copper phthalocyanine/fullerene (CuPc/C-60) bilayer is used for the back cell. An intermediate recombination zone is realized using two doped organic semiconductor layers and a thin noble metal interlayer. The active polymer layer thickness is optimized to ensure matching of the subcell currents. The open circuit voltage V-oc=1 V nearly reaches the sum of the open circuit voltages of each contributing cell. (c) 2006 American Institute of Physics.