Branched chain polymeric metal complexes containing Co(II) or Ni(II) complexes with a donor–π–acceptor architecture: synthesis, characterization, and photovoltaic applications

Four donor–π–acceptor type polymeric metal complexes (PCo–F, PCo–B, PNi–F, and PNi–B) with Co(II) or Ni(II) complexes in the branched chain were synthesized by the Heck coupling and utilized as dyes for dye-sensitized solar cells (DSSCs). The structures, photophysical, electrochemicals, and thermal properties of the four dyes were investigated in detail, and the results showed that dye containing Ni(II) complex and alkoxy benzene unit benefited the generation of photocurrent and the open-circuit voltages. The polymeric metal complexes possess good thermal stability and exhibit good solubility in common organic solvents such as chloroform, THF, and toluene. The maximal power conversion efficiency of 1.21% (Jsc = 2.49 mA/cm2, Voc = 0.695 V, FF = 0.59) was obtained with a DSSCs based on PNi–B dye under simulated air mass 1.5 G solar irradiation.