Research ArticleAPPLIED PHYSICS

Tunable room-temperature spin-selective optical Stark effect in solution-processed layered halide perovskites

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Science Advances  17 Jun 2016:
Vol. 2, no. 6, e1600477
DOI: 10.1126/sciadv.1600477
  • Fig. 1 OSE in PEPI.

    (A) Structure of PEPI with alternating organic and inorganic layers, forming multiple natural type I QW structures, with the barrier (well) being the organic (inorganic) layer (18). CB, conduction band; VB, valence band. (B) Illustration of OSE in a two-level system represented by the equilibrium states (black line) and the pump-induced Floquet quasi-states (green line) and the corresponding linear absorption and TA spectra. (C) The energy separation Δ between the excitonic absorption peak E0 of PEPI (red) and the excitation pump ħω (blue). OD, optical density. (D) TA spectrum of PEPI following a linearly polarized pump-probe at Δt = 0 ps. Inset: Ultrafast kinetics of OSE showing a fast process comparable to the pulse duration. a.u., arbitrary units.

  • Fig. 2 Spin-selective OSE.

    (A) Optical selection rule for the lowest singlet exciton in PEPI. Both the electron and the hole have a total angular momentum quantum number Embedded Image and a magnetic quantum number Embedded Image. (B) Schematic of the spin-selective OSE mechanism in PEPI, showing only the mJ in ket notation. The red (blue) arrow illustrates the interaction between the σ+) photon that forms the Floquet quasi-states (green line). The hybridization of the equilibrium states (red or blue lines) with the Floquet quasi-states results in the shift in energy levels. The dashed (solid) lines represent the energy levels before (after) the repulsion. Repulsion only occurs between the equilibrium states and the Floquet states with the same mJ. (C) Co-circularly and counter-circularly polarized pump and probe TA spectra at various Δt. (D) The corresponding kinetics at the negative ΔA peak (2.37 eV). mOD, milli-optical density.

  • Fig. 3 Fluence dependence of OSE.

    (A) Pump fluence–dependent TA spectra for co-circular (red) and counter-circular (blue) polarization pump-probe at Δt = 0 ps. (B) Resultant spectra from the difference between the co-circular TA spectra and the counter-circular TA spectra at the same pump fluence at a probe delay of 0 ps. The vertical black dashed line indicates the position of the exciton absorption peak. SWT, spectral weight transfer. (C) Estimated Stark shift as a function of pump fluence (green, left axis) and two-photon–excited exciton population (blue, right axis) and as a function of pump fluence (blue, right axis). The Stark shift exhibits a linear relation, whereas the two-photon-excited process exhibits a quadratic relation with the pump fluence.

  • Fig. 4 Correlation between the Rabi energy and the oscillator strength or dielectric contrast.

    Measurement of Rabi energy via OSE on various lead-based 2D perovskite systems (that is, PEPB, PEPI, and FPEPI). There is a clear increasing relation between Embedded Image (red) and the dielectric contrast. Meanwhile, no clear correlation is observed between the oscillator strength (blue) and Embedded Image.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/6/e1600477/DC1

    Experimental setup

    Estimation of energy shift ΔE

    Quantum mechanical description of the OSE

    Estimation of the Rabi energy

    Comparison of the Rabi energy

    Estimation of the equivalent B field for Zeeman splitting of energy levels

    Estimation of the TDM of PEPI

    Estimation of ħΩR and oscillator strength in various organic-inorganic halide perovskite systems

    Estimation of the exciton reduced mass

    Estimation of the radiative lifetime

    Oscillatory signal in PEPI

    Effect of pump polarization ellipticity

    fig. S1. TA spectroscopy setup.

    fig. S2. Calculation of transient change due to a positive x shift.

    fig. S3. Quantum description of OSE.

    fig. S4. OSE with different pump detuning.

    fig. S5. Pump properties in the energy and time domains.

    fig. S6. Comparison of various halide perovskites with different dielectric contrasts.

    fig. S7. Photoluminescence kinetics of PEPI.

    fig. S8. Exciton dynamics in PEPI.

    fig. S9. Polarization ellipticity control experiment of OSE in PEPI.

    table S1. Comparison of OSE and Rabi energy in various inorganic semiconductors.

    References (2836)

  • Supplementary Materials

    This PDF file includes:

    • Experimental setup
    • Estimation of energy shift ΔE
    • Quantum mechanical description of the OSE
    • Estimation of the Rabi energy
    • Comparison of the Rabi energy
    • Estimation of the equivalent B field for Zeeman splitting of energy levels
    • Estimation of the TDM of PEPI
    • Estimation of ħΩR and oscillator strength in various organic-inorganic halide
      perovskite systems
    • Estimation of the exciton reduced mass
    • Estimation of the radiative lifetime
    • Oscillatory signal in PEPI
    • Effect of pump polarization ellipticity
    • fig. S1. TA spectroscopy setup.
    • fig. S2. Calculation of transient change due to a positive x shift.
    • fig. S3. Quantum description of OSE.
    • fig. S4. OSE with different pump detuning.
    • fig. S5. Pump properties in the energy and time domains.
    • fig. S6. Comparison of various halide perovskites with different dielectric contrasts.
    • fig. S7. Photoluminescence kinetics of PEPI.
    • fig. S8. Exciton dynamics in PEPI.
    • fig. S9. Polarization ellipticity control experiment of OSE in PEPI.
    • table S1. Comparison of OSE and Rabi energy in various inorganic
      semiconductors.
    • References (28–36)

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