New organic photosensitizers incorporating carbazole and dimethylarylamine moieties for dye-sensitized solar cells

Four organic dyes (XS10–13) employing carbazole unit as electron donor and N,N-dimethylarylamine moieties as electron-donating groups were designed and synthesized for nanocrystalline TiO2 dye-sensitized solar cells. The electron-donating groups of dimethylarylamine increase the electron density of donor moiety and enhance the molar extinction coefficient of dyes. For a typical device the maximum IPCE value could reach 86%, with a short-circuit photocurrent density (Jsc) of 9.8 mA cm−2, an open-circuit photovoltage (Voc) of 642 mV, and fill factor (FF) of 0.63, which corresponds to an overall conversion efficiency (η) of 4.0%. For a comparison, the N719-sensitized TiO2 solar cell showed an efficiency of 6.4%.

► Four organic dyes were designed and synthesized for dye-sensitized solar cells.
► Carbazole and N,N-dimethylarylamine moieties acted as donating groups.
► High monochromatic incident photon-to-current conversion efficiencies exhibited.