Organic Solar Cells Using Cyanine Dyes
Over the last years, we achieved considerable improvements in the performance of cyanine dye / C60 bilayer heterojunction solar cells. We optimized the performance by oxidative doping of the cyanine layer. Doping increased the film conductivity and induced a steep rise in the short-circuit current and the open-circuit voltage. We argued that cyanine aggregates may be responsible for efficient charge transport to the heterointerface. We described a simple process to match the energy to the low-lying cyanine level by using a thin organic salt layer or doped polyaniline as anode buffer layer. Thereby, hole injection was facilitated and good-performing devices (efficiency = 3%) with a high fill factor (FF = 60%) were fabricated. Recently, we demonstrated inverted bilayer cell architectures with an efficiency of 3.7% and cyanine / cyanine tandem devices with over 4% performance.
The figure shows the architecture of an inverted cyanine solar cell and the J-V characteristics under 1 sun illumination with Jsc = 6.2 mA cm-2, Voc = 0.88 V, FF = 67.8% and efficiency = 3.7%.
F. A. Castro et al., Phys. Chem. Chem. Phys. 2009, 11, 8886; B. Fan et al., Org. Electronics 2010, 11, 583; B. Fan et al., J. Mater. Chem. 2010, 20, 2952; R. Hany et al., Prog. Photovolt: Res. Appl. 2011, 19, 851; E. Berner et al, Appl. Phys. Lett. 2013, 102, 183903; L. Wang et al., Polymer 2014, 55, 3195; S. Jenatsch et al., J. Phys. Chem. C 2014, 118, 17036; H. Zhang et al., Adv. Energy Mater. 2015, 5, 1400734; H. Zhang et al., Org. Electron. 2016, 30, 191.