p-Type Dye-Sensitized Solar Cells Based on Delafossite
CuGaO<sub>2</sub> Nanoplates with Saturation Photovoltages Exceeding
460 mV
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Abstract
Exploring new p-type semiconductor nanoparticles alternative to
the commonly used NiO is crucial for p-type dye-sensitized solar cells
(p-DSSCs) to achieve higher open-circuit voltages (<i>V</i><sub>oc</sub>). Here we report the first application of delafossite
CuGaO<sub>2</sub> nanoplates for p-DSSCs with high photovoltages.
In contrast to the dark color of NiO, our CuGaO<sub>2</sub> nanoplates
are white. Therefore, the porous films made of these nanoplates barely
compete with the dye sensitizers for visible light absorption. This
presents an attractive advantage over the NiO films commonly used
in p-DSSCs. We have measured the dependence of <i>V</i><sub>oc</sub> on the illumination intensity to estimate the maximum obtainable <i>V</i><sub>oc</sub> from the CuGaO<sub>2</sub>-based p-DSSCs.
Excitingly, a saturation photovoltage of 464 mV has been observed
when a polypyridyl Co<sup>3+/2+</sup>(dtb-bpy) electrolyte was used.
Under 1 Sun AM 1.5 illumination, a <i>V</i><sub>oc</sub> of 357 mV has been achieved. These are among the highest values
that have been reported for p-DSSCs