Light-induced picosecond rotational disordering of the inorganic sublattice in hybrid perovskites

Wu, Xiaoxi; Tan, Liang Z.; Shen, Xiaozhe; Hu, T.; Miyata, Kiyoshi; Trinh, M. Tuan; Li, Renkai; Coffee, Ryan; Liu, Shi; Egger, David; Makasyuk, Igor; Zheng, Qiang; Fry, Alan; Robinson, Joseph S.; Smith, Matthew D.; Güzeltürk, Burak; Karunadasa, Hemamala I.; Wang, Xijie; Zhu, Xiaoyang; Kronik, Leeor; Rappe, Andrew M.; Lindenberg, Aaron M.

doi:10.1126/sciadv.1602388

Cited by 166 publications

(201 citation statements)

References 60 publications

(83 reference statements)

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“…In most material systems, scenario (a) is a reasonable assumption. There are two notable examples of case (b): 1) In superconductors, the entry of the sample into the superconducting state causes a shift in both the THz peak amplitude and position, resulting in a change in the real and imaginary part of the complex optical conductivity;40b 2) In the halide perovskites, the combination of phonon anharmonicity and large photoinduced ionic displacement causes a shift in the phonon mode frequency (not just the phonon mode amplitude) after photoexcitation. In these two examples, one should perform 2D‐TRTS instead.…”

Section: Carriers: Free‐carrier Response and Transport Propertiesmentioning

confidence: 99%

Free Carrier, Exciton, and Phonon Dynamics in Lead‐Halide Perovskites Studied with Ultrafast Terahertz Spectroscopy

Zhao

Chia

2019

Advanced Optical Materials

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Terahertz time‐domain spectroscopy is a noncontact, coherent technique that can probe dynamics of carriers, phonons and excitons, and the interplay among these degrees of freedom, which determines the functionalities of the system. In the past few years, lead‐halide perovskites have shown to be a promising class of materials in the areas of solar cells, light emitting diodes, lasers, photodetectors, and field‐effect transistors. In these electronic and photonic devices, the knowledge of the dynamics of charge carriers and other low‐energy excitations is crucial to understand the underlying physics that ultimately determines the device performances. Here, some of the most representative works in the area of halide perovskite research using terahertz time‐domain spectroscopy and time‐resolved terahertz spectroscopy are reviewed, highlighting the power of ultrafast terahertz techniques on this class of material system.

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Section: Carriers: Free‐carrier Response and Transport Propertiesmentioning

confidence: 99%

Free Carrier, Exciton, and Phonon Dynamics in Lead‐Halide Perovskites Studied with Ultrafast Terahertz Spectroscopy

Zhao

Chia

2019

Advanced Optical Materials

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“…Since the point group of the MA ions is C 3 v , the relatively free MA ion rotation at room temperature 19 implies that the highly symmetric point groups assigned to MAPbI 3 may actually be approximations of a more complex dynamic structure 19,20 . Dynamic structural fluctuations can also occur due to phonon modes or the interaction of the MA ions with the PbI framework 28–30 . All these scenarios can induce a so-called dynamic bulk Rashba effect with a characteristic time scale shorter than those of the MA ion rotation (~10 ps) 21 or the vibration of the highest-frequency PbI framework optical mode (~250 fs) 31,32 .…”

Section: Introductionmentioning

confidence: 99%

Inversion symmetry and bulk Rashba effect in methylammonium lead iodide perovskite single crystals

et al. 2018

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Methylammonium lead iodide perovskite (MAPbI3) exhibits long charge carrier lifetimes that are linked to its high efficiency in solar cells. Yet, the mechanisms governing these unusual carrier dynamics are not completely understood. A leading hypothesis—disproved in this work—is that a large, static bulk Rashba effect slows down carrier recombination. Here, using second harmonic generation rotational anisotropy measurements on MAPbI3 crystals, we demonstrate that the bulk structure of tetragonal MAPbI3 is centrosymmetric with I4/mcm space group. Our calculations show that a significant Rashba splitting in the bandstructure requires a non-centrosymmetric lead iodide framework, and that incorrect structural relaxations are responsible for the previously predicted large Rashba effect. The small Rashba splitting allows us to compute effective masses in excellent agreement with experiment. Our findings rule out the presence of a large static Rashba effect in bulk MAPbI3, and our measurements find no evidence of dynamic Rashba effects.

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“…Thus, the refractive phase shift is obviously independent of the decrease in the free carrier density. [41,42] In the same way that the photocarriers can influence the lattice deformation, it should be also possible that local trapped carriers can alter the lattice structure of halide perovskites. However, the existence of long-lived nonradiative trap states has been verified in perovskites by current measurements.…”

Section: Wwwadvopticalmatdementioning

confidence: 99%

“…Here, it should be noted that the band-to-band PL dynamics clarify the free carrier lifetime but cannot provide information about slow nonradiative carrier dynamics. Thus, long-lived nonradiative traps, ion migration, and local symmetry breaking via photoinduced polarization of organic cations or tilting of octahedral bonds [36][37][38][39][40][41][42] are possible origins of the photocarrier-induced refractive-index change. [36,37] Therefore, we consider that the photogenerated carriers trigger long-lived structural changes through nonradiative processes such as carrier trapping, lattice deformation, and local heating by nonradiative carrier recombination and that the experimentally observed large phase shift is a direct result of these photocarrier-induced structural changes.…”

Section: Wwwadvopticalmatdementioning

confidence: 99%

Photorefractive Effect in Organic–Inorganic Hybrid Perovskites and Its Application to Optical Phase Shifter

Tahara

Aharen

Wakamiya

et al. 2018

Advanced Optical Materials

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Besides their polycrystalline thin films and nanocrystals, large-size high-quality perovskite single crystals have been also synthesized recently by solution growth techniques. [23][24][25][26][27][28] With such large single crystals, a better understanding of intrinsic optoelectronic properties can be achieved, which helps in development of photonic applications. The experimentally observed high-efficiency photoluminescence (PL) with no Stokes shift and long PL lifetime provides evidence for an exceptionally low trap density and efficient photon reabsorption. [23][24][25][26][27][28] We note that the low trap density assures a fairly lossless transmission of light with energy below the bandgap. The high transparency for light in the broad spectral range from visible to infrared and the excellent surface flatness of the single crystals are expected to be beneficial for novel all-optical transmittance applications. However, optically controlled transmission properties of halide perovskites have not yet been studied.The photoinduced refractive-index change, which is also called photorefractive effect, is an important property that can be applied in optical switches and phase shifters. Photorefractive effects have been investigated in various materials including oxide perovskites, polymers, and nanomaterials. [29][30][31][32] However, photorefractivity has not been observed in solutionprocessed organic-inorganic hybrid perovskites so far. To clarify whether organic-inorganic hybrid perovskites show photo refractivity or not, a detection method that is sensitive to the refractive-index change is required.In this work, we report the first observation of the photocarrier-induced refractive index change in organic-inorganic perovskites. To reveal the photorefractive effect, we performed an interference detection of the transmitted light that is highly sensitive to its optical phase shift. It is clarified that the photogenerated carriers cause extremely large and long-lived changes in the refractive index, which is evidenced through time-resolved measurements of refractive phase shifts as a function of excitation-pulse fluence, pulse chopping frequency, and pulse repetition rate. By employing the physics of the photocarrierinduced refractive phase shift, we demonstrate that infrared laser light can be tuned to any desired polarization configuration. Furthermore, a polarization modulation technique is accomplished by using the time-dependent refractivity. Our demonstrations open up new ways to develop optical devices with organicinorganic hybrid perovskites such as variable wave plates.Single crystals of methylammonium lead trihalide perovskites with high optical transparency and well-defined facets are grown via solution process. Using these high-quality crystals, the photocarrier-induced refractive-index change is observed for the first time in organic-inorganic hybrid perovskites. The photorefractive properties are measured using a laser interferometric technique that enables to monitor the time-resolved refractive pha...

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Light-induced picosecond rotational disordering of the inorganic sublattice in hybrid perovskites

Abstract: Absorption of light in hybrid perovskite solar cells leads to ultrafast large-amplitude deformations of the inorganic sublattice.

Cited by 166 publications

References 60 publications

Free Carrier, Exciton, and Phonon Dynamics in Lead‐Halide Perovskites Studied with Ultrafast Terahertz Spectroscopy

Free Carrier, Exciton, and Phonon Dynamics in Lead‐Halide Perovskites Studied with Ultrafast Terahertz Spectroscopy

Inversion symmetry and bulk Rashba effect in methylammonium lead iodide perovskite single crystals

Photorefractive Effect in Organic–Inorganic Hybrid Perovskites and Its Application to Optical Phase Shifter

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