Sensitizers of Metal Complexes with Sulfur Coordination Achieving a Power Conversion Efficiency of 12.89.

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 (Jsc) 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 (Td) were 251, 257, 265, 276, and 277 °C, respectively. The result shows that the Jsc 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.

Fabrication of a self-standing supramolecular membrane by a "soft spray" technique.

We report a one-step method to fabricate a free-standing supramolecular membrane composed of melamine and barbituric acid coordinated with silver nitrate (Mba-Ag) at the gas/liquid interface by a soft spray technique. MBa-Ag exhibits a folded two-dimensional layered morphology and thickness of 4.5 µm. The shortwave IR transmittance of MBa-Ag is as high as 95%, which is much higher than the transmittance of UV and visible light, and has the potential for electromagnetic wave transmission.

Effect on absorption and electron transfer by using Cd(ii) or Cu(ii) complexes with phenanthroline as auxiliary electron acceptors (A) in D-A-π-A motif sensitizers for dye-sensitized solar cells.

To broaden the absorption spectrum, improve intramolecular electronic push-pull balance capability, enhance electron transfer and promote the photovoltaic performances of dye sensitizers, four new polymeric metal complex dyes (PBDTT-PhenCd, PBDTT-PhenCu, PPV-PhenCd and PPV-PhenCu) with donor-acceptor-π-bridge-acceptor (D-A-π-A) structure were designed and synthesized. These dyes, for the first time, used the complexes of Cd(ii) or Cu(ii) with phenanthroline as auxiliary electron acceptors (A) instead of organic electron withdrawing groups and adopted thienylbenzo [1,2-b:4,5-b'] dithiophene (BDTT) or hydroquinone (PV) derivatives as electron donors (D) and 8-quinolinol derivatives as π bridge and acceptors (A). The impacts of different auxiliary electron acceptors (A) of metal complexes due to their thermal, optical, electrochemical properties and photovoltaic performance were also investigated. The best power conversion efficiency of 6.68% was achieved in PBDTT-PhenCd DSSC device. In addition, all dyes showed outstanding thermal stability (Td > 300 °C). The results revealed that these novel polymeric metal complex dyes are potential materials for constructing new sensitizers of high performance.

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

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% (J(sc)=4.95 mA/cm(2), V(oc) =0.71 V, FF=69.3%) under AM 1.5 G solar irradiation. It indicates a new way to design dye sensitizers for DSSCs.