Novel Squaraine Cosensitization System of Panchromatic Light-Harvesting with Synergistic Effect for Highly Efficient Solar Cells

Cosensitization based on two or multiple dyes as “dye cocktails” is a convenient shortcut to construct panchromatic dye sensitized solar cells (DSSCs). Generally, extending absorption bands of D-π-A featured organic sensitizers to the long-wavelength and near-infrared (NIR) region through molecular engineering always induces unmatched energy levels (LUMO and HOMO) in DSSCs. In contrast, NIR squaraine dyes commonly exhibit a strong spike-like absorption peak with narrow half-bandwidth in NIR region, along with weak absorption in the visible region, which can bring the relative matched band gap as well as the energy levels for DSSCs. It is expected that squaraine dyes are idea cosensitizers to compensate light-harvesting, which can relieve the constraint in energy levels for D-π-A featured sensitizers. In this work, the efficient spectral-complemental couples of D-A-π-A featured organic dye WS-1 with NIR squaraine dyes VG1-C8 and HSQ4 are well-demonstrated for cosensitized panchromatic solar cells. Interest...