Research ArticleAPPLIED SCIENCES AND ENGINEERING

Tailoring solvent coordination for high-speed, room-temperature blading of perovskite photovoltaic films

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Science Advances  06 Dec 2019:
Vol. 5, no. 12, eaax7537
DOI: 10.1126/sciadv.aax7537
  • Fig. 1 Coordination tailored inks for blade coating of perovskite films.

    (A) Schematic illustration for N2-knife–assisted blade coating of perovskite films at 99 mm/s at room temperature using coordination tailored ink. Insets: Photograph images of as-coated ink, perovskite/intermediate film, and perovskite film. (B) Schematic illustration showing the drying of ink into a perovskite/intermediate film and full crystallization of a perovskite film. VNCS, volatile noncoordinating solvent; NVCS, nonvolatile coordinating solvent.

  • Fig. 2 Coordination capability of different solvents to Pb2+.

    (A) Photograph images showing dissolution of PbI2:MAI = 1:1 and PbI2 alone by GBL, 2-ME, ACN, DMSO, and DMF solvents at nominal mole concentration of 1 M. (B) Ultraviolet-visible (UV-vis) absorption spectra of MAPbI3 solutions prepared from different solvents. O.D., optical density. (C) Vapor pressure and donor number (DN) of the five solvents studied and DN of iodide ion. Scanning electron microscopy (SEM) images of as-coated films from different solvents. Photo credit: Yehao Deng, University of North Carolina Chapel Hill.

  • Fig. 3 Morphology and crystallinity of the perovskite films.

    (A) SEM images of perovskite films prepared with different solvent or solvent mixtures. (B) Cross-sectional SEM images of perovskite films prepared with different solvent mixtures. (C) XRD spectra of as-coated perovskite films from different solvent or solvent mixtures. (D and E) XRD spectra of annealed perovskite films prepared with different solvent mixtures. Red, ACN:2-ME; black, ACN:2-ME:DMSO. a.u., arbitrary units. (F) Maximum coating speed for obtaining high-quality large-area perovskite films when different solvents are applied in N2-knife–assisted blade-coating process. (G) Photograph image of an as-coated perovskite film on 15 cm by 15 cm flexible substrate. Photo credit: Yehao Deng, University of North Carolina Chapel Hill.

  • Fig. 4 Performance characterizations of perovskite solar modules.

    (A) J-V curve of a small-area perovskite solar cell fabricated with the N2-assisted room-temperature blade-coating method. (B) I-V curve of the champion perovskite module. (C) Distribution of efficiencies of 18 modules fabricated consecutively. (D) Long-term operational stability of an encapsulated perovskite module loaded at MPP under 1-sun equivalent illumination. (E) Averaged PCEs of perovskite modules measured at different temperatures from 25° to 85°C with a fitted temperature coefficient of −0.13%/°C. The efficiency of a typical silicon module in the market is also added for reference, which has an efficiency of 17% at 25°C and a temperature coefficient of −0.44%/°C. (F) Efficiencies of a perovskite module with one subcell going through 58 cycles of shading/de-shading. The inset shows schematically how shading is applied over one subcell.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/12/eaax7537/DC1

    Fig. S1. Photographic images of MAPbI3 solutions prepared by dissolving in 2-ME or ACN/2-ME solvent at room temperature and then heated to 80°C.

    Fig. S2. SEM images of N2 knife–assisted blade-coated perovskite films using DMF, GBL, 2-ME, ACN:2-ME, and ACN:2-ME:GBL as solvents.

    Fig. S3. XRD spectra of as-coated films deposited from DMF-, GBL-, or 2-ME–based solutions.

    Fig. S4. UV-vis absorption spectra of perovskite precursor solution based on VNCS with a little DMSO added.

    Fig. S5. Viscosity of ACN, 2-ME, and DMSO solvents.

    Fig. S6. The efficiency uniformity over a perovskite module.

    Fig. S7. NREL certification of a perovskite submodule with an aperture area of 63.7 cm2 and a stabilized efficiency of 16.4%.

    Fig. S8. The performance of a perovskite module under low intensity sun light illumination.

    Fig. S9. The performance of a perovskite module at elevated temperatures.

    Fig. S10. The performance of a perovskite module experiencing shading effect.

    Movie S1. Room-temperature blade coating of perovskite film at 99 mm/s.

  • Supplementary Materials

    The PDFset includes:

    • Fig. S1. Photographic images of MAPbI3 solutions prepared by dissolving in 2-ME or ACN/2-ME solvent at room temperature and then heated to 80°C.
    • Fig. S2. SEM images of N2 knife–assisted blade-coated perovskite films using DMF, GBL, 2-ME, ACN:2-ME, and ACN:2-ME:GBL as solvents.
    • Fig. S3. XRD spectra of as-coated films deposited from DMF-, GBL-, or 2-ME–based solutions.
    • Fig. S4. UV-vis absorption spectra of perovskite precursor solution based on VNCS with a little DMSO added.
    • Fig. S5. Viscosity of ACN, 2-ME, and DMSO solvents.
    • Fig. S6. The efficiency uniformity over a perovskite module.
    • Fig. S7. NREL certification of a perovskite submodule with an aperture area of 63.7 cm2 and a stabilized efficiency of 16.4%.
    • Fig. S8. The performance of a perovskite module under low intensity sun light illumination.
    • Fig. S9. The performance of a perovskite module at elevated temperatures.
    • Fig. S10. The performance of a perovskite module experiencing shading effect.
    • Legend for movie S1

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Room-temperature blade coating of perovskite film at 99 mm/s.

    Files in this Data Supplement:

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