D-A-π-A dye-sensitizers with Cd (Ⅱ) or Cu (Ⅱ) complex as auxiliary electron acceptor

Abstract

In the process of structure modification for dye-sensitizers, D-A-π-A motif sensitizers stood out from various structures of dyes owing to their high efficiencies and long lifetimes. In this work, four novel polymeric metal complex dyes in D-A-π-A pattern (PCZ-QCd, PCZ-QCu, PIDT-QCd and PIDT-QCu), which use Cd (Ⅱ) or Cu (Ⅱ) complexes as auxiliary electron acceptors, indacenodithiophene (IDT) and carbazole (CZ) derivatives as donors and 8-quinolinol derivative as π bridge and acceptors (A) were designed, synthesized and applied to dye-sensitized solar cells (DSSCs). Polymers using different donors and coordination ions are discussed by testing their thermal, optical, electrochemical properties and photovoltaic performance in dye-sensitized solar cells (DSSCs). All polymers show good terminal stability with decomposition temperatures (Td) higher than 300 °C. There is a wide light absorption range in the near ultraviolet and visible region for the polymer (PIDT-QCd) with Cd (Ⅱ) as coordination ion and IDT as donor. As a result, a highest power conversion efficiency of 6.55% was achieved by PIDT-QCd-based DSSC device. This work provides a distinctive perspective for the designing of sensitizers in DSSCs.