Low-frequency Raman study of the ferroelectric phase transition in a layered<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="bold">CuCl</mml:mi><mml:mn mathvariant="bold">4</mml:mn></mml:msub></mml:math>-based organic-inorganic hybrid

Caretta, Antonio; Miranti, Rany; Havenith, Remco W. A.; Rampi, Elia; Donker, Michiel C.; Blake, Graeme R.; Montagnese, M.; Polyakov, Alexey O.; Broer, Ria; Palstra, Thomas; Loosdrecht, P.H.M. van

doi:10.1103/physrevb.89.024301

Cited by 27 publications

(24 citation statements)

References 89 publications

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“…Based on earlier work [42,43], we assign this mode to the motion of the lead iodide octahedra induced by the relative motion of the the organic cation. Due to the localized nature of these vibrations and to the large dynamic disorder intrinsic to the perovskite lattice, the observed mode is usually broadened via inhomogeneous effects as can be seen in the 150-K spectrum ( Fig.…”

Section: Resultsmentioning

confidence: 95%

Stable biexcitons in two-dimensional metal-halide perovskites with strong dynamic lattice disorder

Thouin

Neutzner

Cortecchia

et al. 2018

Phys. Rev. Materials

118

180

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With strongly bound and stable excitons at room temperature, single-layer, two-dimensional organic-inorganic hybrid perovskites are viable semiconductors for light-emitting quantum optoelectronics applications. In such a technological context, it is imperative to comprehensively explore all the factors -chemical, electronic and structural -that govern strong multi-exciton correlations.Here, by means of two-dimensional coherent spectroscopy, we examine excitonic many-body effects in pure, single-layer (PEA) 2 PbI 4 (PEA = phenylethylammonium). We determine the binding energy of biexcitons -correlated two-electron, two-hole quasiparticles -to be 44 ± 5 meV at room temperature. The extraordinarily high values are similar to those reported in other strongly excitonic two-dimensional materials such as transition-metal dichalchogenides. Importantly, we show that this binding energy increases by ∼ 25% upon cooling to 5 K. Our work highlights the importance of multi-exciton correlations in this class of technologically promising, solution-processable materials, in spite of the strong effects of lattice fluctuations and dynamic disorder. * FT and SN are to be considered first co-authors of this manuscript. †

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Section: Resultsmentioning

confidence: 95%

Stable biexcitons in two-dimensional metal-halide perovskites with strong dynamic lattice disorder

Thouin

Neutzner

Cortecchia

et al. 2018

Phys. Rev. Materials

118

180

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“…5 the energy of the vibrational modes at the point, calculated as in Ref. [15], along the y axis is shown as a function of x = 1 − i∈Inorganic q 2 i , where q i are the normalized mean square displacement-so that i q 2 i = 1-of the inorganic ions (Cu and Cl). The resulting diagram suggests a separation of phonons into three types: (i) pure inorganic modes (I ), at x = 0, confined around 250 cm −1 ; (ii) a large number of hybrid modes (H ), with x ∼ 0.5, having energy below 200 cm −1 , and (iii) organic modes (O), at x = 1, above 300 cm −1 .…”

Section: Resultsmentioning

confidence: 99%

“…Details of the structure and of the multiferroic properties can be found in Refs. [13,15]. Small platelets are formed by slow evaporation from the aqueous solution of 2-phenylethylammonium chloride and CuCl 2 • H 2 O salts.…”

Section: Methodsmentioning

confidence: 99%

Measurement of the acoustic-to-optical phonon coupling in multicomponent systems

et al. 2015

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In this paper we investigate the acoustic-to-optical up-conversion phonon processes in a multicomponent system. These processes take place during heat transport and limit the efficiency of heat flow. By combining time-resolved optical and heat capacity experiments we quantify the thermal coupling constant to be g ∼ 0.4 10 17 W/Km 3. The method is based on selective excitation of a part of a multicomponent system, and the measurement of the thermalization dynamics by probing the linear birefringence of the sample with femtosecond resolution. In particular, we study a layered multiferroic organic-inorganic hybrid, in the vicinity of the ferroelectric phase transition. A diverging term of the heat capacity is associated to soft-mode dynamics, in agreement with previous spectroscopy measurements.

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“…On the other hand, displacive transition mechanisms like those of 3D perovskites have also been proposed for the C n MX4 family, which is considered to have a 2D perovskite structure . In the literature, rotational motions of MX 6 octahedra have been designated as soft modes.…”

Section: Resultsmentioning

confidence: 78%

Negative‐to‐Positive Thermal Conductivity Temperature Coefficient Transition Induced by Dynamic Fluctuations of the Alkyl Chains in the Layered Complex (C₄H₉NH₃)₂CuCl₄

Hoshino

Tamura

Akutagawa

2020

Chemistry A European J

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A negative‐to‐positive transition of the temperature coefficients of thermal conductivity was found in the two‐dimensional organic–inorganic layered complex (C4H9NH3)2CuCl4 (C4CuCl4) over the three structural phase transitions in the range 176–218 K. The coefficients of the low‐temperature phases (85–200 K, α and β phases) were negative, as is typical for insulating crystals, whereas those of the high‐temperature phases (200–300 K, γ and δ phases) were positive, as is typical for glasses and liquids. Single‐crystal X‐ray structure analyses revealed that the tilted C4H9NH3+ chains in the α and β phases were fully outstretched in the δ phase, and the interlayer distances between the CuCl42− planes increased significantly. The γ phase was an intermediate phase that crystallized with an incommensurate structure, in which the CuCl42− sheets formed wave‐like structures consisting of connected alternating regions of β‐like and δ‐like moieties. In the γ and δ phases, thermal fluctuations of the C4H9NH3+ chains were found in the electron density maps; however, powder X‐ray diffraction (PXRD) data indicated that the thermal expansion of the C4H9NH3+ layers was restricted by the rigid CuCl42− layers. This situation was considered to induce glass‐like thermal conducting properties in the material, such as a positive temperature coefficient. The mean free path of the phonons estimated by using the thermal conductivities and heat capacities was a function of T−1 in the range 85–200 K, as would be expected for crystals, whereas it was approximately constant in the range 200–300 K, which is typical of glasses. In addition, the existence of soft vibration modes in the two‐dimensional perovskite CuCl42− sheets was revealed by analysis of the incommensurate crystal structure of the γ phase. These low‐energy vibration modes were believed to induce the cooperative phase transitions, along with the thermal fluctuations and van der Waals interactions in the C4H9NH3+ layers.

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Low-frequency Raman study of the ferroelectric phase transition in a layeredCuCl4-based organic-inorganic hybrid

Cited by 27 publications

References 89 publications

Stable biexcitons in two-dimensional metal-halide perovskites with strong dynamic lattice disorder

Stable biexcitons in two-dimensional metal-halide perovskites with strong dynamic lattice disorder

Measurement of the acoustic-to-optical phonon coupling in multicomponent systems

Negative‐to‐Positive Thermal Conductivity Temperature Coefficient Transition Induced by Dynamic Fluctuations of the Alkyl Chains in the Layered Complex (C₄H₉NH₃)₂CuCl₄

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Low-frequency Raman study of the ferroelectric phase transition in a layeredCuCl4-based organic-inorganic hybrid

Cited by 27 publications

References 89 publications

Stable biexcitons in two-dimensional metal-halide perovskites with strong dynamic lattice disorder

Stable biexcitons in two-dimensional metal-halide perovskites with strong dynamic lattice disorder

Measurement of the acoustic-to-optical phonon coupling in multicomponent systems

Negative‐to‐Positive Thermal Conductivity Temperature Coefficient Transition Induced by Dynamic Fluctuations of the Alkyl Chains in the Layered Complex (C4H9NH3)2CuCl4

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Product

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Negative‐to‐Positive Thermal Conductivity Temperature Coefficient Transition Induced by Dynamic Fluctuations of the Alkyl Chains in the Layered Complex (C₄H₉NH₃)₂CuCl₄