Enhanced
Visible Photovoltaic Response of TiO<sub>2</sub> Thin Film with an
All-Inorganic Donor–Acceptor Type Polyoxometalate
- Publication date
- 2015
- Publisher
Abstract
In the field of material chemistry,
it is of great significance to develop abundant and sustainable materials
for solar energy harvesting and management. Herein, after evaluating
the energy band characteristics of 13 kinds of polyoxometalates (POMs),
the trisubstituted POM compound K<sub>6</sub>H<sub>4</sub>[α-SiW<sub>9</sub>O<sub>37</sub>Co<sub>3</sub>(H<sub>2</sub>O)<sub>3</sub>]·17H<sub>2</sub>O (SiW<sub>9</sub>Co<sub>3</sub>) was first studied due to
its relatively smaller band gap (2.23 eV) and higher lowest unoccupied
molecular orbital (LUMO) level (−0.63 V vs NHE). Additionally,
the preliminary computational modeling indicated that SiW<sub>9</sub>Co<sub>3</sub> exhibited the donor–acceptor (D–A) structure,
in which the cobalt oxygen clusters and tungsten skeletons act as
the electron donor and electron acceptor, respectively. By employing
SiW<sub>9</sub>Co<sub>3</sub> to modify the TiO<sub>2</sub> film,
the visible photovoltaic and photocurrent response were both enhanced,
and the light-induced photocurrent at 420 nm was improved by 7.1 times.
Moreover, the highly dispersive and small sized SiW<sub>9</sub>Co<sub>3</sub> nanoclusters loading on TiO<sub>2</sub> were successfully
achieved by fabricating the nanocomposite film of {TiO<sub>2</sub>/SiW<sub>9</sub>Co<sub>3</sub>}<sub>3</sub> with the layer-by-layer
method, which can result in the photovoltaic performance enhancement
of dye-sensitized solar cells (DSSCs), of which the overall power
conversion efficiency was improved by 25.6% from 6.79% to 8.53% through
the synergistic effect of POMs and Ru-complex