Dye-sensitized solar cells with 13% efficiency achieved through the molecular engineering of porphyrin sensitizers

Journal name:
Nature Chemistry
Volume:
6,
Pages:
242–247
Year published:
DOI:
doi:10.1038/nchem.1861
Received
Accepted
Published online

Abstract

Dye-sensitized solar cells have gained widespread attention in recent years because of their low production costs, ease of fabrication and tunable optical properties, such as colour and transparency. Here, we report a molecularly engineered porphyrin dye, coded SM315, which features the prototypical structure of a donor–π-bridge–acceptor and both maximizes electrolyte compatibility and improves light-harvesting properties. Linear-response, time-dependent density functional theory was used to investigate the perturbations in the electronic structure that lead to improved light harvesting. Using SM315 with the cobalt(II/III) redox shuttle resulted in dye-sensitized solar cells that exhibit a high open-circuit voltage VOC of 0.91 V, short-circuit current density JSC of 18.1 mA cm–2, fill factor of 0.78 and a power conversion efficiency of 13%.

At a glance

Figures

  1. Structures of the two dyes used in the study.
    Figure 1: Structures of the two dyes used in the study.

    The structures are coded SM371 and SM315. They both feature a porphyrin core and a bulky bis(2′,4′-bis(hexyloxy)-[1,1′-biphenyl]-4-yl)amine donor. Their acceptor groups differs, with SM315 featuring a benzothiadiazole group.

  2. Absorption spectra of the dyes studied.
    Figure 2: Absorption spectra of the dyes studied.

    The experimental spectra (in THF) are shown as continuous lines and the theoretical electronic transitions are shown as bars for both SM371 (red) and SM315 (black). Theoretical data were computed using LR-TDDFT/M06/IEF-PCM(THF).

  3. Contour plots of selected KS orbitals for the dyes studied.
    Figure 3: Contour plots of selected KS orbitals for the dyes studied.

    The orbitals were calculated for geometry-optimized SM371 (top) and SM315 (bottom), using DFT/M06/IEF-PCM(THF). (Isovalue set to 0.02 a.u.).

  4. Photovoltaic performance of devices made with SM371 and SM315.
    Figure 4: Photovoltaic performance of devices made with SM371 and SM315.

    a, JV curve under AM 1.5G illumination (1,000 W m−2) and b, photocurrent action spectrum for SM371 (red) and SM315 (black).

  5. Transient photocurrent and photovoltage measurements carried out on devices made with SM315 and SM371.
    Figure 5: Transient photocurrent and photovoltage measurements carried out on devices made with SM315 and SM371.

    a, Chemical capacitance and b, electron lifetime as a function of VOC obtained through transient photocurrent and photovoltage measurements.

Compounds

2 compounds View all compounds
  1. 4-{2-[(2Z,7Z,11E,16Z)-7,17-Bis[2,6-bis(octyloxy)phenyl]-12-[bis({4-[2,4-bis(hexyloxy)phenyl]phenyl})amino]-21,23,24,25-tetraaza-22-zincahexacyclo[9.9.3.13,6.113,16.08,23.018,21]pentacosa-1(20),2,4,6(25),7,9,11,13(24),14,16,18-undecaen-2-yl]ethynyl}benzoic acid
    Compound SM371 4-{2-[(2Z,7Z,11E,16Z)-7,17-Bis[2,6-bis(octyloxy)phenyl]-12-[bis({4-[2,4-bis(hexyloxy)phenyl]phenyl})amino]-21,23,24,25-tetraaza-22-zincahexacyclo[9.9.3.13,6.113,16.08,23.018,21]pentacosa-1(20),2,4,6(25),7,9,11,13(24),14,16,18-undecaen-2-yl]ethynyl}benzoic acid
  2. 4-(7-{2-[(2Z,7Z,11E,16Z)-7,17-Bis[2,6-bis(octyloxy)phenyl]-12-[bis({4-[2,4-bis(hexyloxy)phenyl]phenyl})amino]-21,23,24,25-tetraaza-22-zincahexacyclo[9.9.3.13,6.113,16.08,23.018,21]pentacosa-1(20),2,4,6(25),7,9,11,13(24),14,16,18-undecaen-2-yl]ethynyl}-2,1,3-benzothiadiazol-4-yl)benzoic acid
    Compound SM315 4-(7-{2-[(2Z,7Z,11E,16Z)-7,17-Bis[2,6-bis(octyloxy)phenyl]-12-[bis({4-[2,4-bis(hexyloxy)phenyl]phenyl})amino]-21,23,24,25-tetraaza-22-zincahexacyclo[9.9.3.13,6.113,16.08,23.018,21]pentacosa-1(20),2,4,6(25),7,9,11,13(24),14,16,18-undecaen-2-yl]ethynyl}-2,1,3-benzothiadiazol-4-yl)benzoic acid

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Author information

  1. These authors contributed equally to this work

    • Simon Mathew &
    • Aswani Yella

Affiliations

  1. Laboratory of Photonics and Interfaces (LPI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland

    • Simon Mathew,
    • Aswani Yella,
    • Peng Gao,
    • Robin Humphry-Baker,
    • Md. Khaja Nazeeruddin &
    • Michael Grätzel
  2. Laboratory of Computational Chemistry and Biochemistry (LCBC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland

    • Basile F. E. Curchod,
    • Negar Ashari-Astani,
    • Ivano Tavernelli &
    • Ursula Rothlisberger

Contributions

A.Y. and S.M. proposed the research. S.M. synthesized and characterized the dyes with assistance from P.G. A.Y. fabricated and optimized the DSCs and conducted all the photovoltaic characterization. Electrochemical characterization was performed by P.G. R.H.B performed photo-physical characterization and assisted in interpreting the results with assistance from A.Y. and M.G. R.H.B designed the instruments and contributed to interpreting the results. B.F.E.C. and N.A.A. performed the computational characterization, with I.T. and U.R. contributing to the analysis and interpretation of the results. M.K.N. is responsible for overseeing the sensitizer project. M.G. directed the scientific research for this work and assumed all correspondence with the editor and reviewers. S.M. and M.G. prepared the manuscript, with invaluable contributions from A.Y., R.H.B., M.K.N., B.F.E.C., N.A.A., I.T. and U.R.

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The authors declare no competing financial interests.

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