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Room temperature long-range coherent exciton polariton condensate flow in lead halide perovskites

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Science Advances  26 Oct 2018:
Vol. 4, no. 10, eaau0244
DOI: 10.1126/sciadv.aau0244
  • Fig. 1 Microcavity structure and characterization.

    (A) Schematic of the CsPbBr3 microwire microcavity structure, showing x, y, and z axes. (B and C) Microscopy and fluorescence images of CsPbBr3 microwire microcavity after the fabrication process under white light and blue light from a halogen lamp, respectively. Scale bars, 5 μm. (D) Room temperature photoluminescence and absorption spectra of the CsPbBr3 perovskite. Red trace, the absorption spectrum of the CsPbBr3 perovskite on mica substrate, showing a strong excitonic peak at ~2.406 eV. Blue trace, the photoluminescence emission spectrum of the CsPbBr3 perovskite on mica substrate, showing an emission at ~2.353 eV with an FWHM of 60 meV. Olive trace, the ground-state emission of the CsPbBr3 nanowire embedded into the microcavity, showing an emission at ~2.297 eV with an FWHM of ~2.0 meV. a.u., arbitrary units.

  • Fig. 2 Angle-resolved photoluminescence mappings of the CsPbBr3 perovskite microwire microcavity.

    (A) Measured polariton emission dispersions when the long axis x is set to be parallel to the entrance slit of the spectrometer. The white dashed lines show the theoretical fitting dispersions of the upper (UP) and the lower (LP) polariton branches. The white solid lines display the dispersions of the uncoupled CsPbBr3 perovskite exciton (X) and the cavity photon modes (C) obtained from the coupled harmonic oscillator model fitting. (B) Theoretically calculated polariton dispersions when the long axis x is set to be parallel to the entrance slit of the spectrometer. (C) Measured polariton dispersions when the short axis y is set to be parallel to the entrance slit of the spectrometer, showing multiple discrete states. (D) Theoretically calculated polariton dispersions when the short axis y is set to be parallel to the entrance slit of the spectrometer.

  • Fig. 3 Characterization of polariton condensates at room temperature.

    (A) Polariton dispersion at 0.75 Pth, showing a broad distribution at all angles. (B) Polariton dispersion at 1.3 Pth, showing symmetric dominant emission at around ±20°. The polariton condensation with nonzero k inclines the role of polariton propagation. (C) Simulated polariton dispersion mapping at 1.3 Pth. (D) Evolution of emission intensity and linewidth as a function of pumping fluence. (E) Energy blue shift with respect to the polariton emission energy at the lowest pump fluence as a function of pump fluence.

  • Fig. 4 Polariton condensate propagation and characterization at room temperature.

    (A) Schematic of pumping spot and collection spot on the microwire microcavity. (B and C) Measured and simulated real-space images of the microwire microcavity above the polariton condensation threshold, respectively. (D) Polariton group velocity extracted from the polariton dispersion as a function of emission angle (directly related to wave vector k). (E and F) Measured and simulated polariton emission mappings as a function of emission angles, respectively, showing dominant emission at ~−15°.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/10/eaau0244/DC1

    Supplementary Text

    Fig. S1. Measurement of the FWHM of polariton emission at normal incidence.

    Fig. S2. Evidence of perovskite microcavity operating in strong coupling regime.

    Fig. S3. Real-space images of the perovskite microcavity above the threshold.

    Fig. S4. Long-range spatial coherence of the perovskite polariton condensate.

    Fig. S5. Theoretically calculated time-integrated intensity pattern of polaritons generated by pulsed excitation at one end of the microwire.

    Fig. S6. Long-range spatial coherence of propagating polariton condensate.

    Fig. S7. Optical control of polariton condensate.

    Table S1. Detailed comparison between the perovskite polariton and other semiconductor polaritons.

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Text
    • Fig. S1. Measurement of the FWHM of polariton emission at normal incidence.
    • Fig. S2. Evidence of perovskite microcavity operating in strong coupling regime.
    • Fig. S3. Real-space images of the perovskite microcavity above the threshold.
    • Fig. S4. Long-range spatial coherence of the perovskite polariton condensate.
    • Fig. S5. Theoretically calculated time-integrated intensity pattern of polaritons generated by pulsed excitation at one end of the microwire.
    • Fig. S6. Long-range spatial coherence of propagating polariton condensate.
    • Fig. S7. Optical control of polariton condensate.
    • Table S1. Detailed comparison between the perovskite polariton and other semiconductor polaritons.

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