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Photochromic dye-sensitized solar cells with light-driven adjustable optical transmission and power conversion efficiency


Semi-transparent photovoltaics only allow for the fabrication of solar cells with an optical transmission that is fixed during their manufacturing resulting in a trade-off between transparency and efficiency. For the integration of semi-transparent devices in buildings, ideally solar cells should generate electricity while offering the comfort for users to self-adjust their light transmission with the intensity of the daylight. Here we report photochromic dye-sensitized solar cells (DSSCs) based on dyes with a donor-π-conjugated-bridge-acceptor structure where the π-conjugated bridge is substituted by a diphenyl-naphthopyran photochromic unit. DSSCs show change in colour and self-adjustable light transmittance when irradiated and demonstrate a power conversion efficiency up to 4.17%. The colouration–decolouration process is reversible and these DSSCs are stable over 50 days. We also report semi-transparent photo-chromo-voltaic mini-modules (active area of 14 cm²) exhibiting a maximum power output of 32.5 mW after colouration.

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Fig. 1: Photochromic dyes and general photochromic interconversion process.
Fig. 2: Optical and photochromic properties of the dyes.
Fig. 3: Energy band diagram and electron density distributions on the dyes.
Fig. 4: Current density–voltage characteristics of the photochromic solar cells.
Fig. 5: Advanced optical and optoelectronic characterizations of NPI-based semi-transparent solar cells.
Fig. 6: Impedance spectroscopy characterizations of the NPI-based solar cells.
Fig. 7: Stability of NPI-based solar cells under ISOS-D1 test.
Fig. 8: Colour change of a semi-transparent NPI-based mini-module under natural light.

Data availability

The datasets generated and analysed during the current study are available within the paper, its Supplementary Information and its Source Data files (cyclic voltammetry measurements, ultraviolet–visible characterizations, optical and electrical characterizations of solar cells (including: J(V) measurements, IPCE and AVT spectra), impedance spectroscopy measurements and I(V) measurements of the mini-module). All other data related to this work are available from the corresponding author upon reasonable request.


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R.D. acknowledges ANR for funding through the ODYCE project (grant agreement number ANR-14-OHRI-0003-01). J.L. acknowledges CEA for funding through a CFR PhD grant. P.M. thanks GENCI (CINES and IDRIS) for high-performance computing resources (grant 2019-A0060807648). J.A.A. and A.J.R. thank the Ministerio de Ciencia e Innovación of Spain and Agencia Estatal de Investigación and European Union (FEDER) under grant MAT2016-79866-R. A.J.R. thanks the Spanish Ministry of Education, Culture and Sports via a PhD grant (FPU2017-03684). V.M.M. thanks the French Embassy in Kenya through Campus France for a scholarship grant. R.D. acknowledges the European Research Council for funding. This project has received funding under the European Union’s Horizon 2020 research and innovation programme (grant agreement number 832606; project PISCO).

Author information

Authors and Affiliations



Q.H., D.J., J.L. and Y.K. synthesized and characterized the dyes. P.M. performed the DFT calculations. V.M.M., S.N. and F.O. fabricated, optimized and characterized the solar cells and mini-modules. A.J.R. and J.A.A. investigated the solar cells by EIS and performed the IPCE measurements. R.D. designed the materials and experiments. R.D. treated the data and wrote the manuscript, with contributions from all authors. All authors have given approval to the final version of the manuscript.

Corresponding author

Correspondence to Renaud Demadrille.

Ethics declarations

Competing interests

R.D., D.J. and Y.K. are employees of CEA, which holds a patent on this technology (inventors: R.D., D.J. and Y.K.; current assignee: Commissariat à l’Energie Atomique et aux Energies Alternatives; application number: 17305597.1; date of publication: 28 November 2018). S.N is currently an employee of Solaronix, which sells electrodes and chemical components that are used in this study.

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Supplementary information

Supplementary Information

Supplementary Notes 1–8, Tables 1–14, Figs. 1–30 and refs. 1–6.

Reporting Summary

Supplementary Video

Demonstration of the simultaneous colouration and photovoltaic energy conversion for a photochromic semi-transparent solar cell (dimension of cell: 5 cm × 5 cm; indoor natural light).

Supplementary NMR Data

NMR spectra of the dyes and intermediates.

Supplementary Computational Data

Computational data for the three dyes.

Supplementary Figure Data

Source data for the: cyclic voltammetry traces (CV NPL, CV NPB and CV NPI); AVT of semi-transparent solar cells (AVT NPL, AVT NPB and AVT NPI); IPCE spectra of opaque solar cells (IPCE NPL, IPCE NPB and IPCE NPI); steady-state output, NPI-based opaque cell (SteadyState-NPI-Cell); and current–voltage characteristics of the NPI mini-module ((I(V) NPI-minimodule).

Source data

Source Data Fig. 2

Source data on ultraviolet–visible absorption spectra and kinetics (NPL, NPB and NPI).

Source Data Fig. 4

Source data on current–voltage characteristics for the solar cells (NPL, NPB and NPI).

Source Data Fig. 5

Source data on ultraviolet–visible absorption spectra, AVT, IPCE and bleaching curves for NPI-based semi-transparent solar cells.

Source Data Fig. 6

Source data on impedance spectroscopy measurements.

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Huaulmé, Q., Mwalukuku, V.M., Joly, D. et al. Photochromic dye-sensitized solar cells with light-driven adjustable optical transmission and power conversion efficiency. Nat Energy 5, 468–477 (2020).

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