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1. p-Type Dye-Sensitized Solar Cells
Based on Delafossite CuGaO2
Nanoplates with Saturation
Photovoltages Exceeding 460 mV
Mingzhe Yu, Gayatri Natu, Zhiqiang Ji,
and Yiying Wu*
*Department of Chemistry & Biochemistry, The Ohio
State University, 100 West 18th Avenue, Columbus,
Ohio 43210, United States
J. Phys. Chem. Lett. 2012, Vol. 3, 1074 -1078 1

2. Motivations
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 (Voc).
Delafossite CuGaO2 has a lower valence band maximum(VBM)
compared to NiO and therefore could provide a larger Voc in p-DSSCs.
In contrast to the dark colored NiO, the CuGaO2 nanoplates are white
because of the large band-gap. Therefore, the porous films made of these
nanoplates barely compete with the dye sensitizers for visible light
absorption.
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3. Material Synthesis and Characterization
Hydrothermal synthesis with ethylene glycol(EG) and cetrimonium
bromide(CTAB) was employed to get CuGaO2 nanoplates :
Cu(NO3)2 KOH Colloid Hydrothermal
Ca(NO3)3 Products
pH~5
CTAB EG 193oC, 52hrs
CuGaO2
NiO
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4. CuGaO2 nanoplate’s thermal-stability
It’s important to make sure that CuGaO2 won’t decompose during the thermal-
treatment in the solar cell fabrication process because of the existence of Cu+.
The X-ray diffraction(XRD) pattern showed that CuGaO2 is thermo-kinetically
stable when heated below 350oC.
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5. Saturation-Voc measurements for solar cells
CuGaO2-based p-DSSCs exhibited significant higher saturation-Voc, which
indicates the maximum obtainable Voc, than NiO-based cells under intense
illumination:
(Solar cell configuration: photocathode: CuGaO2 film on FTO; dye: P1;
electrolyte: I3-/I-/MPN or Co3+/2+(dtb-bpy) /MeCN; counter-electrode: Pt-
FTO )
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6. CuGaO2-DSSCs J-V performance
A Voc as 357mV in Co3+/2+(dtb-bpy) electrolyte was achieved and it’s among the
highest values that have been reported.
More research is undergoing to increase the current intensity.
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7. Conclusion
We report the first application of light-
colored CuGaO2 nanoplates in p-DSSCs
that produce high photovoltages.
A Voc of 357 mV has been achieved with a Acknowledgments
Co3+/2+(dtb-bpy) electrolyte under 1 Sun The authors acknowledge the
AM 1.5 illumination. And more funding support from the U.S.
remarkably, a saturation photovoltage of Department of Energy (Award
464 mV has been achieved with the No. DE-FG0207ER46427).
increasing illumination intensity.
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