New D−π–A-conjugated organic sensitizers based on 4H-pyran-4-ylidene donors for highly efficient dye-sensitized solar cells

Abstract

We have synthesized a series of four new promising D−π–A conjugated organic sensitizers with a proaromatic 4H-pyran-4-ylidene as a donor, a thiophene ring in the bridge, and 2-cyanoacrilic acid as acceptor. Comparison between different donor substituents and the modification of the thiophene ring resulted in molar extinction coefficients as high as 36399 M–1 cm–1 at 551 nm. The photovoltaic properties of the DSSCs demonstrate power conversion efficiencies as high as 5.4%.