Near-infrared Absorbing Squarylium Dyes with Linearly Extended π-Conjugated Structure for Dye-sensitized Solar Cell Applications

A novel class of near-infrared absorbing squarylium sensitizers with linearly extended pi-conjugated structures, which were obtained by Pd-catalyzed cross-coupling reactions with stannylcyclobutenediones, has been developed for dye-sensitized solar cells. The cells based on these dyes exhibited a significant spectral response in the near-Infrared region over 750 nm in addition to the visible region.