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J Am Chem Soc. 2015 Apr 29;137(16):5602-9. doi: 10.1021/jacs.5b01946. Epub 2015 Apr 16.

Boosting power conversion efficiencies of quantum-dot-sensitized solar cells beyond 8% by recombination control.

Author information

1
†Key Laboratory for Advanced Materials, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China.
2
‡Photovoltaic, Optoelectronic Devices Group, Department de Física, Universitat Jaume I, 12071 Castelló, Spain.
3
¶Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
4
∥Graduate School Material Science in Mainz, University of Mainz, Staudingerweg 9, 55099 Mainz, Germany.
5
§Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 22254, Saudi Arabia.

Abstract

At present, quantum-dot-sensitized solar cells (QDSCs) still exhibit moderate power conversion efficiency (with record efficiency of 6-7%), limited primarily by charge recombination. Therefore, suppressing recombination processes is a mandatory requirement to boost the performance of QDSCs. Herein, we demonstrate the ability of a novel sequential inorganic ZnS/SiO2 double layer treatment onto the QD-sensitized photoanode for strongly inhibiting interfacial recombination processes in QDSCs while providing improved cell stability. Theoretical modeling and impedance spectroscopy reveal that the combined ZnS/SiO2 treatment reduces interfacial recombination and increases charge collection efficiency when compared with conventional ZnS treatment alone. In line with those results, subpicosecond THz spectroscopy demonstrates that while QD to TiO2 electron-transfer rates and yields are insensitive to inorganic photoanode overcoating, back recombination at the oxide surface is strongly suppressed by subsequent inorganic treatments. By exploiting this approach, CdSe(x)Te(1-x) QDSCs exhibit a certified record efficiency of 8.21% (8.55% for a champion cell), an improvement of 20% over the previous record high efficiency of 6.8%, together with an additional beneficial effect of improved cell stability.

PMID:
25860792
DOI:
10.1021/jacs.5b01946

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