NIR-Absorbing Heptamethine Dyes with Tailor-Made Counterions for Application in Light to Energy Conversion

A method to exchange the counterion
of cyanine dyes to Δ-TRISPHAT– and PF6– is presented.
The influence of these counterions on the photophysical and electrochemical
properties of the cyanine dye in solution is discussed, and tendencies
in the solid packing are highlighted by X-ray crystal structures.
The compounds were applied in semitransparent bilayer organic solar
cells together with C60, and a power conversion efficiency
of 2.2% was achieved while maintaining a high transparency level in
the visible region of 66%.