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Hydroxamic acid pre-adsorption raises the efficiency of cosensitized solar cells

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Dye-sensitized solar cells (DSCs) convert light into electricity by using photosensitizers adsorbed on the surface of nanocrystalline mesoporous titanium dioxide (TiO2) films along with electrolytes or solid charge-transport materials1,2,3. They possess many features including transparency, multicolour and low-cost fabrication, and are being deployed in glass facades, skylights and greenhouses4. Recent development of sensitizers5,6,7,8,9,10, redox mediators11,12,13 and device structures14 has improved the performance of DSCs, particularly under ambient light conditions14,15,16,17. To further enhance their efficiency, it is pivotal to control the assembly of dye molecules on the surface of TiO2 to favour charge generation. Here we report a route of pre-adsorbing a monolayer of a hydroxamic acid derivative on the surface of TiO2 to improve the dye molecular packing and photovoltaic performance of two newly designed co-adsorbed sensitizers that harvest light quantitatively across the entire visible domain. The best performing cosensitized solar cells exhibited a power conversion efficiency of 15.2% (which has been independently confirmed) under a standard air mass of 1.5 global simulated sunlight, and showed long-term operational stability (500 h). Devices with a larger active area of 2.8 cm2 exhibited a power conversion efficiency of 28.4% to 30.2% over a wide range of ambient light intensities, along with high stability. Our findings pave the way for facile access to high-performance DSCs and offer promising prospects for applications as power supplies and battery replacements for low-power electronic devices18,19,20 that use ambient light as their energy source.

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Fig. 1: Molecular structures and effects of BPHA pre-adsorbers on the dye assembly on the TiO2 surface.
Fig. 2: Effects of the BPHA preadsorbent on the device performances.
Fig. 3: Performance of DSCs under ambient lighting conditions.

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Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.


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We are grateful to O. Ouellette for help with PL measurements, M. Chang and J.-H. Yum for help with ATR–FTIR measurements, A. Krishna for assisting in device stability tests, Q. Feng for help with 1H NMR (800 MHz) spectra measurements, and D. Türkay for the current–voltage measurements at the PV lab of IEM in Neuchâtel. Y.R., S.M.Z. and M.G. acknowledge financial support from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 826013. D.Z., J.S. and A.H. are grateful for the financial support of the Swiss National Science Foundation under contract SNSF 200020_185041.

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Authors and Affiliations



M.G. and A.H. supervised the study. Y.R. conceived the idea. Y.R. and D.Z. designed the experiments, fabricated, optimized and characterized the solar cells, and analysed the data together with F.T.E. Y.R. designed the SL9 and SL10 photosensitizers and performed the synthesis and characterization of SL9. J.S. completed the synthesis and characterization of SL10. Y.C. conceptually contributed to the project and discussed the data. Y.R. measured UV–vis absorption spectra and dye loading amount. F.T.E. carried out the PLQY and TRPL measurements and analysis, and characterized the ambient light devices together with Y.R. F.T.E also provided the hydroxamic acid that had been used in his previous research at BASF. Y.R.and D.Z. performed and analysed the ATR–FTIR measurements. N.V. performed and analysed the cyclic voltammetry experiments. Y.R. conducted the TCSPC and electrochemical impedance spectroscopy measurements, and carried out the data analysis. Y.R., D.Z. and Y.C. wrote the initial draft of the manuscript, which M.G. corrected. M.G. wrote the covering letter and prepared the final version of the response to the reviewer’s comments. All authors reviewed the final version of the manuscript. S.M.Z., A.H. and M.G. coordinated the work.

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Correspondence to Yiming Cao, Anders Hagfeldt or Michael Grätzel.

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Nature thanks Alessandro Abbotto, Chun-Guey Wu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Methods, Figs. 1–33, Notes 1–6, Tables 1–5 and refs. 1–7.

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Ren, Y., Zhang, D., Suo, J. et al. Hydroxamic acid pre-adsorption raises the efficiency of cosensitized solar cells. Nature 613, 60–65 (2023).

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