Synthesis and Photovoltaic Properties of the Novel Dye of Branched Chain Polymeric Metal Complexes with Cyclopentadithiophene Derivatives as a Donor

Abstract

Four novel donor-π -acceptor dyes (P1-P4) based on branched chain polymeric metal complexes were designed and synthesized, which use cyclopentadithiophene or fluorene derivatives as an electron donor (D), phenanthroline metal complex as an electron acceptor (A), and thiophene as a π -bridge (π ). The photovoltaic performances of dye-sensitized solar cells (DSSCs) based on the four polymers were investigated. The results show that they all have good thermal stability (T d, P1 313°C, P2 320°C, P3 306°C, P4 340°C), and the dyes with cyclopentadithiophene derivatives as a donor (P1 and P2) show higher power conversion efficiency (P1 2.41%, P2 2.31%) than that with fluorene derivatives (P3 1.65%, P4 1.52%) under standard illumination due to their broader absorptions in the UV-visible region and lower band gaps. It indicates a new way to design stable and highly efficient DSSCs with novel conjugated organic polymers as dyes. C