Novel dye sensitizers of polymeric metal complexes with benzodithiophene derivatives as donor and their photovoltaic performance

• Four novel polymeric metal complexes were synthesized and investigated in Dye-sensitized solar cells.
• The light harvesting efficiency and photo-current of cadmium polymer complexes are better than zinc polymer complexes.
• The four polymeric metal complexes show excellent thermal stability.

Four novel donor–acceptor (D–A) type conjugated polymeric metal complexes (P1–P4) bearing benzodithiophene or carbazole derivative as donors were synthesized, characterized and applied as dye sensitizers in dye-sensitized solar cells (DSSCs). Salicylaldehyde derivative complexes acted as electron acceptors, Zn(II) or Cd(II) was chosen as the coordinated metal ion, and diaminomaleonitrile was ancillary ligand in these structures. The thermal, photophysical, electrochemical and photovoltaic properties of these polymeric metal complexes were investigated by FT-IR, GPC, TGA, DSC, UV-Vis absorption spectroscopy, elemental analysis, cyclic voltammetry (CV), J–V curves and IPCE plots. These polymer dyes exhibit good thermal stability for their application in DSSCs. The DSSC device based on P2 which contains benzodithiophene derivative as donor and Cd(II) as coordination ion, exhibited the highest power conversion efficiency of 2.43% (Jsc = 4.95 mA/cm2, Voc = 0.71 V, FF = 69.3%) under AM 1.5 G solar irradiation. It indicates a new way to design dye sensitizers for DSSCs.

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