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Dye-sensitized solar cells for efficient power generation under ambient lighting

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Solar cells that operate efficiently under indoor lighting are of great practical interest as they can serve as electric power sources for portable electronics and devices for wireless sensor networks or the Internet of Things. Here, we demonstrate a dye-sensitized solar cell (DSC) that achieves very high power-conversion efficiencies (PCEs) under ambient light conditions. Our photosystem combines two judiciously designed sensitizers, coded D35 and XY1, with the copper complex Cu(II/I)(tmby) as a redox shuttle (tmby, 4,4′,6,6′-tetramethyl-2,2′-bipyridine), and features a high open-circuit photovoltage of 1.1 V. The DSC achieves an external quantum efficiency for photocurrent generation that exceeds 90% across the whole visible domain from 400 to 650 nm, and achieves power outputs of 15.6 and 88.5 μW cm–2 at 200 and 1,000 lux, respectively, under illumination from a model Osram 930 warm-white fluorescent light tube. This translates into a PCE of 28.9%.

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Figure 1: Molecular photovoltaics with Cu(II/I)(tmby)2 redox mediator and XY1 and D35 sensitizers.
Figure 2: Photovoltaic characteristics of D35/XY1 co-sensitized systems with Cu(tmby)2 as the redox mediator.
Figure 3
Figure 4: Absorption spectroscopy and time-resolved laser spectroscopy of interfacial electron transfer that involve the D35 and XY1 sensitizers.
Figure 5: Photovoltaic characteristics of co-sensitized DSCs measured under indoor-light conditions.

Change history

  • 08 May 2017

    In the version of this Article originally published online, in the abstract, the units for power output should have been 'μW cm–2'; thus, the values should have read '15.6 and 88.5 μW cm–2'. This has now been corrected in all versions of the Article.


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We acknowledge the Swiss National Science Foundation for financial support with the project entitled ‘Fundamental studies of mesoscopic devices for solar energy conversion’, project no. 200021_157135/1, and the NCCR MUST research instrument. J.H. and X.Y. thank NSFC/China (21421004 and 91233207) and the Programme of Introducing Talents of Discipline to Universities (B16017). We appreciate the technical support of R. Humphry-Baker, P. Comte and J.-D. Decoppet. We are also very grateful to G24power for the comparative measurements of the GaAs Alta solar cells under indoor-light conditions.

Author information




A.H. supervised the study. M.F. conceived the work and designed the experiments. M.F. and M.G. wrote the manuscript with feedback from the co-authors. M.F., P.L. and Y.S. fabricated and characterized the solar cells. M.F. assembled the devices, and analysed and synthesized the copper complexes. Y.S. prepared the PEDOT counter electrodes. X.Z. and J.H. were responsible for the XY1 dye synthesis and characterization. J.T. and J.-E.M. performed and analysed the PIA and transient spectroscopy measurements. F.G. contributed to the electrolyte and device characterization. S.M.Z. and M.G. coordinated the work.

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Correspondence to Michael Grätzel or Anders Hagfeldt.

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The authors declare no competing financial interests.

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Freitag, M., Teuscher, J., Saygili, Y. et al. Dye-sensitized solar cells for efficient power generation under ambient lighting. Nature Photon 11, 372–378 (2017).

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