Research ArticleMATERIALS SCIENCE

Ultrahigh sensitivity of methylammonium lead tribromide perovskite single crystals to environmental gases

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Science Advances  27 Jul 2016:
Vol. 2, no. 7, e1600534
DOI: 10.1126/sciadv.1600534
  • Fig. 1 XRD and optical properties of MAPbBr3 single crystals.

    (A) hk0 reciprocal lattice plane reconstructed from MAPbBr3 single crystal XRD data at room temperature. Inset: Image of one of the measured crystals grown from solution. (B) PL spectra in vacuum and air (the PL intensity in vacuum is two orders of magnitude lower than in air). (C) Variation in PL intensity of MAPbBr3 crystals from air-vacuum-air environments. a.u., arbitrary units. (D) Normalized PL spectra at different times in (C). (E and F) Two-dimensional (2D) pseudocolor plots of TRPL spectra taken in air and vacuum with an excitation power density of 0.71 μJ/cm2. (G) Decay of the PL at a wavelength of 560 nm in air and vacuum.

  • Fig. 2 Effect on the PL intensity of MAPbBr3 single crystals of exposure to different gaseous environments.

    (A) PL intensity as a function of time in vacuum and on exposure to dry N2, dry CO2, and dry Ar. (B) PL intensity as a function of time on exposure to air, dry O2, and moist N2. In each panel, the blue shaded area indicates vacuum. The crystal was excited with a 400-nm wavelength laser; the laser power was kept constant at 0.71 μJ/cm2.

  • Fig. 3 Two-photon excited fluorescence in MAPbBr3 crystal and single-photon excited optical properties of cleaved crystal surface.

    (A) 2D pseudocolor plot of two-photon (800 nm) excited TRPL measured in air. (B) TRPL dynamics [extracted from measurement reported in (A)]; the fit gives lifetimes of t1 = 34 ns and t2 = 4.5 μs. Inset: Image of MAPbBr3 crystal under two-photon excitation (TPE) with an excitation wavelength of 800 nm. (C) Two-photon excited PL spectra measured in air and vacuum. (D) 2D pseudocolor plot of TRPL of a freshly cleaved crystal in air; the excitation wavelength is 400 nm. The emission peak wavelength as a function of time is indicated by the red line. (E) Calculated photocarrier density profile at various times under 400-nm laser excitation. Inset: Image of MAPbBr3 crystal under single-photon excitation (SPE) with an excitation wavelength of 400 nm. (F) Calculated PL spectra at various times after excitation.

  • Fig. 4 Effect of surface recombination on the optical properties of MAPbBr3 crystal.

    (A) Schematic image showing photoexcitation and deep levels within the forbidden gap in proximity to the surface. hvex, excitation laser; Ec, conduction band; Ev, valence band. (B) PL lifetime in bulk single crystals as a function of SRV for various carrier diffusion coefficients and bulk lifetimes. (C) PL lifetime in polycrystalline thin film or small crystals for various surface recombination velocities.

  • Fig. 5 Electronic properties of MAPbBr3 single-crystal devices.

    (A) Structure of the single-crystal device for current-voltage (I-V) measurement. (B and C) Side-view and top-view of a single-crystal device. (D) I-V curves of the MAPbBr3 single-crystal device under laser illumination in air and vacuum. (E) Dark current of the MAPbBr3 single-crystal device in air and vacuum.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/7/e1600534/DC1

    fig. S1. Powder XRD pattern of crushed MAPbBr3 crystals.

    fig. S2. PL excitation spectrum and PL of a MAPbBr3 single crystal measured at room temperature in ambient air.

    fig. S3. Photostability of MAPbBr3 single crystal.

    fig. S4. PL spectra taken at different vacuum levels.

    fig. S5. PL spectra of crystals prepared by the AVC technique in vacuum and air.

    fig. S6. Steady-state and TRPL spectrum from a freshly cleaved crystal prepared by the ITC technique in vacuum and air.

    fig. S7. TRPL decay in vacuum from a crystal grown by ITC.

    fig. S8. PL intensity variation in different gases.

    fig. S9. Normalized PL spectra in different gases.

    fig. S10. PL intensity as a function of time in air under two-photon excitation (800 nm).

    fig. S11. Photocarrier distribution at t = 0 under single- and two-photon excitation conditions.

    fig. S12. TRPL spectrum from a crystal prepared by the ITC technique under lower power density of 400-nm excitation.

    movie S1. Perovskite crystal under excitation of a 400-nm wavelength laser from an atmosphere of air to vacuum and then to air.

    References (4345)

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Powder XRD pattern of crushed MAPbBr3 crystals.
    • fig. S2. PL excitation spectrum and PL of a MAPbBr3 single crystal measured at room temperature in ambient air.
    • fig. S3. Photostability of MAPbBr3 single crystal.
    • fig. S4. PL spectra taken at different vacuum levels.
    • fig. S5. PL spectra of crystals prepared by the AVC technique in vacuum and air.
    • fig. S6. Steady-state and TRPL spectrum from a freshly cleaved crystal prepared by the ITC technique in vacuum and air.
    • fig. S7. TRPL decay in vacuum from a crystal grown by ITC.
    • fig. S8. PL intensity variation in different gases.
    • fig. S9. Normalized PL spectra in different gases.
    • fig. S10. PL intensity as a function of time in air under two-photon excitation (800 nm).
    • fig. S11. Photocarrier distribution at t = 0 under single- and two-photon excitation conditions.
    • fig. S12. TRPL spectrum from a crystal prepared by the ITC technique under lower power density of 400-nm excitation.
    • References (4345)

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    Other Supplementary Material for this manuscript includes the following:

    • movie S1 (.mp4 format). Perovskite crystal under excitation of a 400-nm wavelength laser from an atmosphere of air to vacuum and then to air.

    Files in this Data Supplement:

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