Synthesis of a novel heptamethine–cyanine dye for use in near-infrared active dye-sensitized solar cells with porous zinc oxide prepared at low temperature

A novel near-infrared-absorbing heptamethine–cyanine dye (KFH-3) that contains four n-butyl groups was synthesized for use in highly efficient dye-sensitized solar cells with porous zinc oxide (ZnO) prepared at low temperature, and resulted in remarkable performance characteristics, such as a conversion efficiency of 1.23% (AM 1.5) with an incident photon-to-current conversion efficiency (800 nm) of 33%, a short-circuit photocurrent density of 3.34 mA, an open-circuit photovoltage of 0.49, and a fill factor of 0.76, using almost solely the near-infrared region of sunlight.