Quantum dot solar cells with 8% efficiency

17 04 2015

Quantum dot layer solar cells have recently appeared in Tables with high (9%) efficiency. But here we show that quantum dot solar cells with TiO2 framework are also progressing rapidly and now show a certified 8% efficiency.

Furthermore this paper incorporates Enrique Canovas and Mischa Bonn to the previous team and we provide new fundamental insights with respect to the common image of injection and charge separation in the quantum dot solar cells

Boosting Power Conversion Efficiencies of Quantum-Dot-Sensitized Solar Cells Beyond 8% by Recombination Control

Ke Zhao, Zhenxiao Pan, Iván Mora-Seró, Enrique Cánovas, Hai Wang, Ya Song, Xueqing Gong, Jin Wang, Mischa Bonn, Juan Bisquert§, and Xinhua Zhong*
J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/jacs.5b01946
Publication Date (Web): April 10, 2015
Copyright © 2015 American Chemical Society
ja-2015-019465_0007
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/SiO2treatment 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, CdSexTe1–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.

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