Metal-Cluster-Sensitized Solar Cells. A New Class
of Thiolated Gold Sensitizers Delivering Efficiency Greater Than 2%
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Abstract
A new
class of metal-cluster sensitizers has been explored for
designing high-efficiency solar cells. Thiol-protected gold clusters
which exhibit molecular-like properties have been found to inject
electrons into TiO<sub>2</sub> nanostructures under visible excitation.
Mesoscopic TiO<sub>2</sub> films modified with gold clusters deliver
stable photocurrent of 3.96 mA/cm<sup>2</sup> with power conversion
efficiencies of 2.3% under AM 1.5 illumination. The overall absorption
features and cell performance of metal-cluster-sensitized solar cells
(MCSCs) are comparable to those of CdS quantum-dot-based solar cells
(QDSCs). The relatively high open-circuit voltage of 832 mV and fill
factor of 0.7 for MCSCs as compared to QDSCs show the viability of
these new sensitizers as alternatives to semiconductor QDs and sensitizing
dyes in the next generation of solar cells. The superior performance
of MCSCs discussed in this maiden study lays the foundation to explore
other metal clusters with broader visible absorption