Highly mobile hot holes in Cs
            <sub>2</sub>
            AgBiBr
            <sub>6</sub>
            double perovskite

Zhang, Heng; Debroye, Elke; Zheng, Wenhao; Fu, Shuai; Virgilio, Lucia Di; Kumar, Pushpendra; Bonn, Mischa; Wang, Hai I.

doi:10.1126/sciadv.abj9066

Cited by 32 publications

(28 citation statements)

References 47 publications

(72 reference statements)

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“…The first term of Eq. ( 2) indicates the DS portion, which accounts for the disorder or backscattering induced transport of mobile charge carriers [81][82][83] . ε 0 is the vacuum permittivity.…”

Section: Resultsmentioning

confidence: 99%

Photoinduced large polaron transport and dynamics in organic–inorganic hybrid lead halide perovskite with terahertz probes

et al. 2022

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Organic-inorganic hybrid metal halide perovskites (MHPs) have attracted tremendous attention for optoelectronic applications. The long photocarrier lifetime and moderate carrier mobility have been proposed as results of the large polaron formation in MHPs. However, it is challenging to measure the effective mass and carrier scattering parameters of the photogenerated large polarons in the ultrafast carrier recombination dynamics. Here, we show, in a one-step spectroscopic method, that the optical-pump and terahertz-electromagnetic probe (OPTP) technique allows us to access the nature of interplay of photoexcited unbound charge carriers and optical phonons in polycrystalline CH3NH3PbI3 (MAPbI3) of about 10 μm grain size. Firstly, we demonstrate a direct spectral evidence of the large polarons in polycrystalline MAPbI3. Using the Drude–Smith–Lorentz model along with the Frӧhlich-type electron-phonon (e-ph) coupling, we determine the effective mass and scattering parameters of photogenerated polaronic carriers. We discover that the resulting moderate polaronic carrier mobility is mainly influenced by the enhanced carrier scattering, rather than the polaron mass enhancement. While, the formation of large polarons in MAPbI3 polycrystalline grains results in a long charge carrier lifetime at room temperature. Our results provide crucial information about the photo-physics of MAPbI3 and are indispensable for optoelectronic device development with better performance.

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Section: Resultsmentioning

confidence: 99%

Photoinduced large polaron transport and dynamics in organic–inorganic hybrid lead halide perovskite with terahertz probes

et al. 2022

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“… 25 Strong electron–phonon coupling is expected to lead to lattice distortion/displacement that can disturb a periodic potential experienced by charge carriers, giving rise to polaronic effects, broadening, and a Stokes shift of light emission, and also impacts carrier mobility. 26 − 29 All of these effects could also be affected by the ordering of B cations in the lattice. 30 , 31 Therefore, understanding lattice dynamics and electron–phonon interactions in Cs 2 NaFeCl 6 is of great importance not only for fundamental insights but also for future optoelectronic and spintronic applications.…”

Section: Introductionmentioning

confidence: 99%

Lattice Dynamics and Electron–Phonon Coupling in Double Perovskite Cs₂NaFeCl₆

Zhang

Klarbring

et al. 2023

J. Phys. Chem. C

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Phonon–phonon and electron/exciton–phonon coupling play a vitally important role in thermal, electronic, as well as optical properties of metal halide perovskites. In this work, we evaluate phonon anharmonicity and coupling between electronic and vibrational excitations in novel double perovskite Cs2NaFeCl6 single crystals. By employing comprehensive Raman measurements combined with first-principles theoretical calculations, we identify four Raman-active vibrational modes. Polarization properties of these modes imply Fm3̅m symmetry of the lattice, indicative for on average an ordered distribution of Fe and Na atoms in the lattice. We further show that temperature dependence of the Raman modes, such as changes in the phonon line width and their energies, suggests high phonon anharmonicity, typical for double perovskite materials. Resonant multiphonon Raman scattering reveals the presence of high-lying band states that mediate strong electron–phonon coupling and give rise to intense nA 1g overtones up to the fifth order. Strong electron–phonon coupling in Cs2NaFeCl6 is also concluded based on the Urbach tail analysis of the absorption coefficient and the calculated Fröhlich coupling constant. Our results, therefore, suggest significant impacts of phonon–phonon and electron–phonon interactions on electronic properties of Cs2NaFeCl6, important for potential applications of this novel material.

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“…Instead of only recording the change of the THz peak electric field after the photoexcitation, one can detect the whole THz waveform with ( E pump ( t )) and without ( E 0 ( t )) optical excitations (and thus their difference Δ E ( t ) = E pump ( t ) – E 0 ( t )) at a fixed pump–sampling delay time by moving the optical delay lines for the pump beam and sampling beam simultaneously. 38 By Fourier transformation of E 0 ( t ) and Δ E ( t ), the complex photoconductivity spectra σ(ω) are achieved as follows: …”

Section: Methodsmentioning

confidence: 99%

Stable Mott Polaron State Limits the Charge Density in Lead Halide Perovskites

et al. 2022

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Large polarons are known to form in lead halide perovskites (LHPs). Photoinduced isolated polarons at low densities have been well-researched, but many-body interactions at elevated polaron densities, exceeding the Mott criterion (i.e., Mott polaron density), have remained elusive. Here, employing ultrafast terahertz spectroscopy, we identify a stable Mott polaron state in LHPs at which the polaron wavefunctions start to overlap. The Mott polaron density is determined to be ∼1018 cm–3, in good agreement with theoretical calculations based on the Feynman polaron model. The electronic phase transition across the Mott density is found to be universal in LHPs and independent of the constituent ions. Exceeding the Mott polaron density, excess photoinjected charge carriers annihilate quickly within tens to hundreds of picoseconds, before reaching the stable and long-lived Mott state. These results have considerable implications for LHP-based devices and for understanding exotic phenomena reported in LHPs.

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Highly mobile hot holes in Cs ₂ AgBiBr ₆ double perovskite

Abstract: Ultrafast terahertz spectroscopy reveals excess energy-dependent highly mobile hot holes in Cs 2 AgBiBr 6 double perovskites.

Cited by 32 publications

References 47 publications

Photoinduced large polaron transport and dynamics in organic–inorganic hybrid lead halide perovskite with terahertz probes

Photoinduced large polaron transport and dynamics in organic–inorganic hybrid lead halide perovskite with terahertz probes

Lattice Dynamics and Electron–Phonon Coupling in Double Perovskite Cs₂NaFeCl₆

Stable Mott Polaron State Limits the Charge Density in Lead Halide Perovskites

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Highly mobile hot holes in Cs 2 AgBiBr 6 double perovskite

Abstract: Ultrafast terahertz spectroscopy reveals excess energy-dependent highly mobile hot holes in Cs 2 AgBiBr 6 double perovskites.

Cited by 32 publications

References 47 publications

Photoinduced large polaron transport and dynamics in organic–inorganic hybrid lead halide perovskite with terahertz probes

Photoinduced large polaron transport and dynamics in organic–inorganic hybrid lead halide perovskite with terahertz probes

Lattice Dynamics and Electron–Phonon Coupling in Double Perovskite Cs2NaFeCl6

Stable Mott Polaron State Limits the Charge Density in Lead Halide Perovskites

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Highly mobile hot holes in Cs ₂ AgBiBr ₆ double perovskite

Lattice Dynamics and Electron–Phonon Coupling in Double Perovskite Cs₂NaFeCl₆