Application of semisquaric acids as sensitizers for zinc oxide solar cell

A series of semisquaric acids were examined as sensitizers for the zinc oxide solar cell prepared by a one-step cathode deposition template method. Their cell performance was rather low due to high oxidation potential (Eox) of semisquaric acids. However, the performance was improved by introducing long alkyl group on the nitrogen atom at the heteroaromatic moiety. A N-octadecylindolium derivative showed the best performance: the incident photon-to-current efficiency (IPCE) 38.0% at absorption maximum (λmax) 423 nm, short circuit photocurrent density (Isc) 1.116 mA cm−2, open circuit photovoltage (Voc) 0.421 V, fill factor (ff) 0.57, and solar-light-to-electricity conversion efficiency (η) 0.27%, respectively.