Research ArticleMATERIALS SCIENCE

Perovskite nanowire–block copolymer composites with digitally programmable polarization anisotropy

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Science Advances  31 May 2019:
Vol. 5, no. 5, eaav8141
DOI: 10.1126/sciadv.aav8141
  • Fig. 1 Perovskite nanowire–block copolymer supramolecular nanocomposites.

    (A) Schematic diagram of the perovskite crystal structure. (B) PL of CsPbX3 (X = I, Br, and Cl) perovskite nanowires in toluene solution. Halide composition determines the material’s bandgap and color of emitted light (λexcitation = 380 nm). (C) TEM images of naturally aligned bundles of CsPbBr3 perovskite nanowires (length, ~1 μm; diameter, ~10 nm). (D) TEM images (top) and SAXS measurements (bottom) of the pure SIS filaments without nanowires printed using 1-mm-diameter nozzle (left, horizontally printed sample; right, filament cross sections), demonstrating microphase separated SIS hexagonal domains with long-range order and anisotropy. Red arrow indicates printing and the microdomain alignment direction. (E) A maximum intensity projection of z-stack fluorescence confocal image of the printed nanowire-block copolymer filament (diameter, 100 μm; λexcitation = 365 nm). (F) Representative TEM images of nanocomposite filaments printed using 1-mm-diameter nozzle showing perovskite nanowires oriented in parallel with the print direction and locally conform to the SIS block copolymer microdomains. A higher-magnification TEM image (inset) shows that nanowires primarily segregate to PI-rich domains (see also fig. S6 and table S4). The TEM samples in (D) and (F) are sectioned using cryo-ultramicrotome and stained with OsO4, which selectively darkens the PI domains.

  • Fig. 2 Polarized emission from printed perovskite nanocomposites.

    (A) Fourier images showing the angular emission from a nanowire bundle in the printed filament. Polar angle (θ) is plotted radially from 0° (center) to 70° (outer edge). Azimuthal angle (φ) is plotted around the circle starting at the right-hand side. Fourier image of a horizontal (left) and a vertical (right) filament on glass slide (cartoons, top). Angular emission pattern shows alignment of nanowires along filament axis. (B) Polarized emission of printed nanowire composites, measured using one linear polarizer installed in the emission path and two linear polarizers installed in both the excitation and emission paths. a.u., arbitrary units. (C) Artistic example of printed composites using their polarized emission (adapted from M. C. Escher, Sky and Water I art). Different parts are revealed for (left) no polarization, (middle) horizontal polarization, and (right) vertical polarization. Scale bars, 1 mm.

  • Fig. 3 Polarized perovskite nanocomposites via 3D printing.

    (A) A photo (left) is downsized to a 3-bit grayscale image consisting of 60 (w) × 90 (h) square-shaped pixels (left, inset). Taking advantage of the polarization angle–dependent emission intensities, we convert the grayscale intensities to eight different printing directions (top right) and print the image (middle). (B) Polarization holograms. When viewed using a pair of linear polarizers, the two-layer device projects an image of Taj Mahal (horizontally printed, horizontal polarization) and Forbidden City (vertically printed, vertical polarization). (C and D) A mechano-optical metamaterial based on an auxetic structure. (C) The unit cell (top) consists of four rotating squares, which can rotate up to 45°. The polarization-dependent emission results in a strain-intensity relationship (bottom). (D) This structure is flexible and can adhere to a finger (top). Undergoing reversible stretching motions, the digitally patterned H letter (printed in vertical direction and in parallel with the polarizers) is displayed (left) or encrypted (right).

  • Fig. 4 Polarizer tunable color multiplexing.

    (A) Polarized PL spectra of the printed nanocomposites incorporating CsPbBr3 (green), CsPb(Br0.2I0.8)3 (red), and CsPb(Br0.2Cl0.8)3 (blue) nanowires, taken with a pair of two linear polarizers installed in both the excitation and emission paths. (B) Optical images of printed pixel arrays showing polarization-dependent emission multiplexing. Images are taken using a multiphoton microscope with a polarized excitation source and with a linear polarizer in the emission path. (C) Spectral emission profiles of the pixel array based on hexagonal tiles of red, green, and blue light-emitting perovskite nanocomposites printed along three directions oriented with a 60° difference upon rotating both polarizers. (D) Its corresponding colors on CIE 1931 chromaticity diagram (right). Two types of potential display operations are presented (see also figs. S14 and S15). The solid line and triangles represent colors using the multiplexed RGB pixel arrays in (B). NWs, nanowires. The dashed lines and circles represent the multiplexed RG, RB, and GB pixel arrays printed in two orthogonal directions shown in fig. S14.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/5/eaav8141/DC1

    Fig. S1. Optical properties of CsPbBr3 nanowires.

    Fig. S2. Nanowire absorption spectra.

    Fig. S3. Stability of CsPb(Br0.2I0.8)3 nanowires.

    Fig. S4. Nanocomposite ink rheology.

    Fig. S5. SAXS measurements of SIS block copolymer inks.

    Fig. S6. TEM images of printed and cast nanocomposites.

    Fig. S7. Polarization dependence of printed nanocomposite filaments composed of inks containing 50 wt % SIS with 0.05 wt % perovskite nanowires as a function of printing speed.

    Fig. S8. Fourier imaging setup.

    Fig. S9. Fourier images of printed SIS-CsPbBr3 block copolymer nanocomposites.

    Fig. S10. Measuring dipole alignment from Fourier images.

    Fig. S11. Emission polarization of printed nanocomposite filaments.

    Fig. S12. Five-layer photonic device showing “L-I-G-H-T” pattern imaged using polarized fluorescence microscopy along the z direction.

    Fig. S13. Embedded 3D printing of perovskite nanowire ink in a transparent viscoplastic matrix housed within a cubic mold.

    Fig. S14. Fluorescence images of printed pixel arrays showing polarization-dependent emission multiplexing using two nanowire composites printed in orthogonal directions.

    Fig. S15. Schematics of different display operations presented in CIE 1931 diagram (Fig. 4D).

    Table S1. Comparison of PLQY for different perovskite nanowires.

    Table S2. Fluorescence stability of red-emitting CsPb(Br0.2I0.8)3 nanowires embedded in a polymer.

    Table S3. Printing pressures used for patterning nanocomposite inks at varying nozzle sizes and print speeds.

    Table S4. Hildebrand solubility and surface energies of species used to form nanocomposite inks.

    Table S5. Comparison of different techniques for aligning semiconductor nanowires.

    References (3744)

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Optical properties of CsPbBr3 nanowires.
    • Fig. S2. Nanowire absorption spectra.
    • Fig. S3. Stability of CsPb(Br0.2I0.8)3 nanowires.
    • Fig. S4. Nanocomposite ink rheology.
    • Fig. S5. SAXS measurements of SIS block copolymer inks.
    • Fig. S6. TEM images of printed and cast nanocomposites.
    • Fig. S7. Polarization dependence of printed nanocomposite filaments composed of inks containing 50 wt % SIS with 0.05 wt % perovskite nanowires as a function of printing speed.
    • Fig. S8. Fourier imaging setup.
    • Fig. S9. Fourier images of printed SIS-CsPbBr3 block copolymer nanocomposites.
    • Fig. S10. Measuring dipole alignment from Fourier images.
    • Fig. S11. Emission polarization of printed nanocomposite filaments.
    • Fig. S12. Five-layer photonic device showing “L-I-G-H-T” pattern imaged using polarized fluorescence microscopy along the z direction.
    • Fig. S13. Embedded 3D printing of perovskite nanowire ink in a transparent viscoplastic matrix housed within a cubic mold.
    • Fig. S14. Fluorescence images of printed pixel arrays showing polarization-dependent emission multiplexing using two nanowire composites printed in orthogonal directions.
    • Fig. S15. Schematics of different display operations presented in CIE 1931 diagram (Fig. 4D).
    • Table S1. Comparison of PLQY for different perovskite nanowires.
    • Table S2. Fluorescence stability of red-emitting CsPb(Br0.2I0.8)3 nanowires embedded in a polymer.
    • Table S3. Printing pressures used for patterning nanocomposite inks at varying nozzle sizes and print speeds.
    • Table S4. Hildebrand solubility and surface energies of species used to form nanocomposite inks.
    • Table S5. Comparison of different techniques for aligning semiconductor nanowires.
    • References (3744)

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