No abstract

In the study to improve the light absorption range and intensity of dye sensitizers in the visible region and promote their photovoltaic performance, five novel polymeric metal complexes with sulfur coordination (BDTT-VBT-Ni, BDTT-VBT-Cu, BDTT-VBT-Zn, BDTT-VBT-Cd, and BDTT-VBT-Hg) to be used as D–A−π–A motif dye sensitizers were designed, synthesized, and characterized. In these polymeric metal complexes with sulfur coordination, the metal complexes with sulfur coordination of benzodithiophene derivatives are used as auxiliary electron acceptors, 8-quinolinol derivatives are used as π-bridge and electron acceptors, and thienylbenzene-[1,2-b:4,5-b′] dithiophene (BDTT) are used as electron donors. The effect of different metal complexes with sulfur coordination on the photovoltaic performance of dye sensitizers has been systematically studied. Under AM 1.5 irradiation (100 mW cm–2), the devices of dye-sensitized solar cells (DSSCs) based on five polymeric metal complexes with sulfur coordination exhibited a short-circuit current density (J sc) of 13.43, 15.07, 18.00, 18.99, and 20.78 mA cm–2, respectively, and their power conversion efficiencies (PCEs) were 7.10, 8.59, 10.68, 11.23, and 12.89%, respectively, and their thermal decomposition temperatures (T d) were 251, 257, 265, 276, and 277 °C, respectively. The result shows that the J sc and PCE of five polymeric metal complexes increase by degrees, and the PCE of BDTT-VBT-Hg is up to 12.89%, which is because of the strength of the coordination bonds between Ni­(II), Cu­(II), Zn­(II), Cd­(II), and Hg­(II) and sulfur increases in turn so that the electron-withdrawing ability and electron-transfer ability of auxiliary electron acceptors is enhanced. These results provide a new way to develop stable and efficient metal complexes with sulfur coordination dye sensitizers in the future.

Donor-acceptor-π bridge-acceptor (DÀ AÀ πÀ A) motif dyes are promising dye sensitizers in dye-sensitized solar cells (DSSCs). In this study, to strengthen with-drawing electron force of the auxiliary electron acceptors(A) in DÀ AÀ πÀ A motif dye sensitizers, the metal complexes unit is be used as auxiliary electron acceptor(A) instead of organic electron-withdrawing monomer. The four polymeric metal complexes were designed, synthesized, and characterized, which used metal complexes of phenanthroline derivatives as auxiliary acceptors (A), benzodithiophene-dithiophene derivatives (BDTT) as donors (D), and 8hydroxyquinoline derivatives as π-bridges and acceptors of the dye sensitizers, and have been used for dye sensitizers. Under AM 1.5 G (100 mW cm À 2 ), the photovoltaic test results indicated that the short-circuit photocurrent density (J sc ) of the DSSCs based four polymeric metal complexes are 11.26, 13.68, 14.42 and 15.57 mA cm À 2 and power conversion efficiency (PCE) are 5.96 %, 7.83 %, 8.07 %, 9.28 % respectively. Both J sc and PCE value of the four polymeric metal complexes increased in order. This may be due to the fact that larger radius of metal ion under the same change number can enhance the coordination bond and cause stronger electron-withdrawing ability of auxiliary acceptor and stronger charge-transfer ability between the donor and the acceptor, which results in higher J sc and higher PCE of the polymeric complex dye sensitizer.