Dynamic polaronic screening for anomalous exciton spin relaxation in two-dimensional lead halide perovskites

Tao, Weijian; Zhou, Qi; Zhu, Haiming

doi:10.1126/sciadv.abb7132

Cited by 71 publications

(99 citation statements)

References 47 publications

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“…Imperfectly, the maximum

Δ T

signal for

σ^{+}

probe is only ≈70% and ≈80% at 293 K and 77 K (Figure 5c), respectively; which is not the expected 100% J ‐polarized signal, indicating complex spin relaxation mechanisms. In Elliott–Yafet (E–Y) mechanism, [ 34,42,58 ] spin relaxation rate (

τ_{s}^{- 1}

) is proportional to momentum scattering rate,

τ_{normals}^{- 1} \propto τ_{normalp}^{- 1} χ^{2}

where

τ_{p}^{- 1}

is momentum scattering rate, χ describes SOC‐induced spin‐mixing factor. In nondegenerate CH 3 NH 3 PbI 3 system, the

τ_{s}^{- 1}

governed by E–Y mechanism is given by

τ_{normals}^{- 1} \propto τ_{normalp}^{- 1} T^{2}

Equation (9) indicates that the spin relaxation of carrier momentum scattering in CH 3 NH 3 PbI 3 is mainly due to phonon scattering with temperature dependence.…”

Section: Typical Study Cases and Discussionmentioning

confidence: 99%

“…According to E–Y mechanism, effective magnetic field can be generated by spin‐orbit interaction, which mixes wavefunctions with opposite spins. [ 42 ] As discussed in Section 3.1.1, the spin relaxation in polycrystalline CH 3 NH 3 PbI 3 thin film is mainly governed by E–Y mechanism. Hence, it is quite interesting to study the photo‐induced magnetization behaviors by leveraging circularly polarized pump‐probe technique.…”

Section: Typical Study Cases and Discussionmentioning

confidence: 99%

“…The linear trend for co‐circular polarization indicates no multi‐particle process involved, while the saturation signature for counter‐circular polarization implies nonradiative trap‐filling process occurred. The spin polarization ( P ) is defined as [ 41,42,46 ]

P = \frac{{((), normalΔ T / T)}_{co} - {((), normalΔ T / T)}_{counter}}{{((), normalΔ T / T)}_{co} + {((), normalΔ T / T)}_{counter}}

Note that the calculation method here is for the system average population that contains a mixture of excitons and free carriers. By assuming spin‐flip probability to be α because of momentum scattering during thermalization, the experimentally observable spin polarization can be expressed as

P = P_{0} e^{- α Δ E}

where P 0 refers to photo‐induced spin polarization, and

Δ E = E_{pump} - E_{probe}

denotes energy difference between pump and probe photon energy.…”

Section: Typical Study Cases and Discussionmentioning

confidence: 99%

“…However, fundamental understanding of spin‐dependent photo‐physics in perovskites, in particular of, hyperfine description of spin relaxation, magnetic spin effect, and spin polarization processes, which is plausible for manipulation of spin electrons by spin photons leveraging circularly‐polarized pump‐probe technique, is still at its nascent stage. [ 30–32,34–37,40–48 ] Moreover, up to date, few review papers have been reported on systematic, complete, and insightful summary and discussion of such emerging ultrafast spin‐quantum dynamics and phenomena in various perovskites from the aspect of study via this technique. [ 23,49,50 ] Hence, it is highly desirable for providing a systemic review on this rapidly developing field in recent few years, to evoke extraordinary research on spintronic properties in perovskites for truly practical spintronic devices in future.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Ultrafast Pump‐Probe Spectroscopy—A Powerful Tool for Tracking Spin‐Quantum Dynamics in Metal Halide Perovskites

2021

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Ultrafast pump‐probe spectroscopy provides a powerful tool for deep insight into sophisticated electron–hole dynamics for materials development and devices optimization, particularly for emerging metal halide perovskites (hereafter, termed perovskites), due to their great potentials for optoelectronic and photonic applications in solar cells, light‐emitting diodes, photodetectors, and lasers. Recently, flourishing spin‐related photophysical phenomena (such as, Rashba effect, optical Stark effect, and magnetooptical effect) in perovskites and their relevant devices have experimentally been observed, attributed to huge spin‐orbital coupling effect and strong interaction of electron–photon in perovskites. However, fundamental understanding of spin‐dependent photophysics in perovskites is still at its nascent stage. In recent few years, circularly‐polarized ultrafast pump‐probe technique has pushed burgeoning development of spin‐selective photophysics in perovskites for spintronic device applications. Nevertheless, few review papers summarize this emerging field systematically, completely, and insightfully. Herein, to evoke broader attraction and research interest, recent advances in spin‐quantum dynamics in perovskites revealed by circularly‐polarized pump‐probe technique are reviewed: from the fundamentals and theories of circularly‐polarized ultrafast pump‐probe transient absorption and time‐resolved Faraday rotation spectroscopy; to the recent enlightening works on spin relaxation dynamics, spin‐selective exciton optical Stark effect, magnetic spin effect, and spin polarization dynamics. Finally, current challenges and perspectives are given.

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“…Imperfectly, the maximum

Δ T

signal for

σ^{+}

τ_{s}^{- 1}

) is proportional to momentum scattering rate,

τ_{normals}^{- 1} \propto τ_{normalp}^{- 1} χ^{2}

where

τ_{p}^{- 1}

is momentum scattering rate, χ describes SOC‐induced spin‐mixing factor. In nondegenerate CH 3 NH 3 PbI 3 system, the

τ_{s}^{- 1}

governed by E–Y mechanism is given by

τ_{normals}^{- 1} \propto τ_{normalp}^{- 1} T^{2}

Equation (9) indicates that the spin relaxation of carrier momentum scattering in CH 3 NH 3 PbI 3 is mainly due to phonon scattering with temperature dependence.…”

Section: Typical Study Cases and Discussionmentioning

confidence: 99%

Section: Typical Study Cases and Discussionmentioning

confidence: 99%

P = \frac{{((), normalΔ T / T)}_{co} - {((), normalΔ T / T)}_{counter}}{{((), normalΔ T / T)}_{co} + {((), normalΔ T / T)}_{counter}}

P = P_{0} e^{- α Δ E}

where P 0 refers to photo‐induced spin polarization, and

Δ E = E_{pump} - E_{probe}

denotes energy difference between pump and probe photon energy.…”

Section: Typical Study Cases and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultrafast Pump‐Probe Spectroscopy—A Powerful Tool for Tracking Spin‐Quantum Dynamics in Metal Halide Perovskites

2021

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“…The re-emergence of two-dimensional metal halide perovskites (2D MHPs) [1][2][3] with large exciton binding energies has not only fueled technological interest, 4,5 but also provided an excellent material platform to explore intriguing excitonic many-body physics [6][7][8][9][10][11] via various advanced spectroscopies. From a technological standpoint, such spectroscopic studies are used to explore and determine the material handles that enable optimization of desirable optoelectronic properties -light emission, charge photo-generation and transport.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Tin Substitution on the Excitonic Properties of Two Dimensional Metal Halide Perovskites

Folpini¹,

Palummo²,

Cortecchia³

et al. 2021

Preprint

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<div>With growing interest in the lead-free derivatives of the metal-halide perovskites (MHP), it is imperative to fully understand the contribution of the metal cation to their desirable excitonic characteristics. Here, we explore this question by performing an in-depth spectroscopic and theoretical analysis of phenethylammonium tin iodide ((PEA)<sub>2</sub>SnI<sub>4</sub>), a prototypical tin based MHP, and rigorously compare it with its lead counterpart. We elaborate on the origin of multiple excitonic resonances uniquely observed in the linear absorption spectrum of (PEA)<sub>2</sub>SnI<sub>4</sub> at energies about 200-300meV above the primary exciton. By performing calculations based on density functional theory and many- body perturbation theory, we suggest that the excitonic series at these higher energies are composed of electronic transitions from a lower lying valence band. Importantly, the valence band splitting is driven by the octahedral conformations that follow subtle variations in the organic-inorganic interactions within the crystal lattice. We experimentally show that the presence of the higher energy excitonic resonance results in a relatively slow nanosecond component in the formation dynamics of the primary exciton, in addition to the ultrafast phonon-driven hot carrier thermalization. While the presence of such slow relaxation channel for the excitons might be beneficial to many optoelectronic applications, our work suggests its possible control via systematic design of the organic cation. Moreover, our observations indicate that spin-orbit coupling does not play a primary role in the intricate yet crucial changes in the excitonic characteristics imparted by the tin substitution.</div>

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Carrier–Phonon Interaction Induced Large Negative Thermal‐Optic Coefficient at Near Band Edge of Quasi‐2D (PEA)₂PbBr₄ Perovskite

Chien

et al. 2023

Adv Funct Materials

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The soft and polar nature of quasi‐2D (PEA)2PbBr4 perovskite, and robust photo‐generated excitons lead exciton‐polaritons and exciton‐polarons as the important phenomena near the band edge for application in the lighting aspect. In this work, a convenient methodology is proposed based on the polariton resonant modes in temperature‐dependent (77 K to RT) spectroscopy, and investigate the effect of these quasi‐particles on refractive index dispersion. The large binding energy (≈335 meV) of quasi‐2D excitons is obtained by the reflectance measurements at 77 K. Stable exciton‐polaritons and exciton‐polarons are confirmed by energy dispersions and the observation of self‐trapped exciton‐polaron state, respectively. Furthermore, the large negative thermal‐optic coefficient due to damping effect of exciton‐phonon scattering is observed. The phenomenon is opposite to those observed in conventional semiconductors (e.g., Si, Ge, GaN, AlN, GaAs, AlAs, and ZnO etc.). The observed stable negative thermal‐optic coefficients from 160 K to RT indicate that the quasi‐2D perovskite can be used as a phase compensator for conventional semiconductor materials.

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Dynamic polaronic screening for anomalous exciton spin relaxation in two-dimensional lead halide perovskites

Cited by 71 publications

References 47 publications

Ultrafast Pump‐Probe Spectroscopy—A Powerful Tool for Tracking Spin‐Quantum Dynamics in Metal Halide Perovskites

Ultrafast Pump‐Probe Spectroscopy—A Powerful Tool for Tracking Spin‐Quantum Dynamics in Metal Halide Perovskites

The Effect of Tin Substitution on the Excitonic Properties of Two Dimensional Metal Halide Perovskites

Carrier–Phonon Interaction Induced Large Negative Thermal‐Optic Coefficient at Near Band Edge of Quasi‐2D (PEA)₂PbBr₄ Perovskite

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Dynamic polaronic screening for anomalous exciton spin relaxation in two-dimensional lead halide perovskites

Cited by 71 publications

References 47 publications

Ultrafast Pump‐Probe Spectroscopy—A Powerful Tool for Tracking Spin‐Quantum Dynamics in Metal Halide Perovskites

Ultrafast Pump‐Probe Spectroscopy—A Powerful Tool for Tracking Spin‐Quantum Dynamics in Metal Halide Perovskites

The Effect of Tin Substitution on the Excitonic Properties of Two Dimensional Metal Halide Perovskites

Carrier–Phonon Interaction Induced Large Negative Thermal‐Optic Coefficient at Near Band Edge of Quasi‐2D (PEA)2PbBr4 Perovskite

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Resources

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Carrier–Phonon Interaction Induced Large Negative Thermal‐Optic Coefficient at Near Band Edge of Quasi‐2D (PEA)₂PbBr₄ Perovskite