A Novel Carboxyethyltin Functionalized Sandwich-type Germanotungstate: Synthesis, Crystal Structure, Photosensitivity, and Application in Dye-Sensitized Solar Cells

A novel sandwich-type germanotungstate
[C­(NH2)3]10[Mn2{Sn­(CH2)2COOH}2(B-α-GeW9O34)2]·8H2O (1) represents
the first single crystalline polyoxometalate (POM) functionalized
by open chain carboxyethyltin, which was designed and synthesized
in aqueous solution and applied to a dye-sensitized solar cell (DSSC)
for the first time. Its photosensitivity was explored through a fluorescence
spectrum (FL), surface photovoltage spectrum (SPV), electrochemical
method, and solid diffuse spectrum. 1 displays the primary
features of sensitizers in DSSCs, and the efficiency of the solar
cell is 0.22%. Delightedly, when 1 was employed to assemble
a cosensitized solar cell configuration by preparing a 1-doped TiO2 electrode and additionally adsorbing N719
dyes, a considerably improved efficiency was achieved through increasing
spectral absorption and accelerating electron transport, which is
19.4% higher than that of single N719 sensitization. This result opens
up a new way to position different dyes on a single TiO2 film for cosensitization.