Structural Phase Transitions in CsPbBr<sub>3</sub>

Hirotsu, Shunsuke; Harada, J.; Iizumi, M.; Gesi, K.

doi:10.1143/jpsj.37.1393

Cited by 271 publications

(259 citation statements)

References 15 publications

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“…We consider that the frame of PbBr 6 octahedrons is so rigid that it will dominate the environment of MA molecules. The condensation of rotational motion of PbBr 6 octahedrons around the principal axes will induce the successive phase transition, as in the case of CsPbX 3 [1,2] . But the freezing of the rotational modes couples with the ordering of MA molecules, which will give the large entropy change.…”

Section: Discussionmentioning

confidence: 99%

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Disordered Configuration of Methylammonium of CH₃NH₃PbBr₃Determined by Single Crystal Neutron Diffractometry

et al. 2007

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In order to understand the mechanism of the structural phase transition in CH 3 NH 3 PbBr 3 , neutron diffraction data from the single crystal is analyzed by the least-squares method and the maximum entropy method. The disordered configuration of a methylammonium ion in a cage surrounded by eight PbBr 6 octahedrons is identified unambiguously. With comparing the low-temperature structure, the transition is characterized by the condensation of the rotational motion of the PbBr 6 octahedron around the Pb-Br axis, which accompanies the partial ordering of the methylammonium ion to reduce the site symmetry.

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Section: Discussionmentioning

confidence: 99%

“…If the oxygen is replaced by halogen X, ABX 3 may also take the perovskite structure. Such examples are CsPbX 3 (X=Cl and Br) [1,2] ; the crystals transform from the cubic phase (Pm3m) to a tetragonal phase (P4/mbm), but no polar phase is reported down to low temperature.…”

Section: Introductionmentioning

confidence: 99%

Disordered Configuration of Methylammonium of CH₃NH₃PbBr₃Determined by Single Crystal Neutron Diffractometry

et al. 2007

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“…The transition temperatures agree with previously reported XRD values, which are indicated by white lines in Figure 1a. [11,12,18,19] arXiv:1705.10691v2 [cond-mat.mtrl-sci] …”

mentioning

confidence: 99%

“…The transition temperatures agree with previously reported XRD values, which are indicated by white lines in Figure 1a. [11,12,18,19] In light of these apparent differences, and to understand the unique interaction of MA and the lead-halide network, we measured the Raman spectra at higher frequencies, corresponding to internal CH 3 NH 3 PbBr 3 Raman modes (Figure 1e and f). The peak at ≈ 320 cm −1 , observed in both bromide crystals (supporting information), appears to correspond to a 480 cm −1 peak in CH 3 NH 3 PbCl 3 .…”

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Interplay between organic cations and inorganic framework and incommensurability in hybrid lead-halide perovskite CH3NH3PbBr3

Guo

Yaffe

Paley

et al. 2017

Phys. Rev. Materials

107

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Organic-inorganic coupling in the hybrid lead-halide perovskite is a central issue in rationalizing the outstanding photovoltaic performance of these emerging materials. Here we compare and contrast the evolution of structure and dynamics of the hybrid CH3NH3PbBr3 and the inorganic CsPbBr3 lead-halide perovskites with temperature, using Raman spectroscopy and single-crystal Xray diffraction. Results reveal a stark contrast between their order-disorder transitions, abrupt for the hybrid whereas smooth for the inorganic perovskite. X-ray diffraction observes an intermediate incommensurate phase between the ordered and the disordered phases in CH3NH3PbBr3. Lowfrequency Raman scattering captures the appearance of a sharp soft mode in the incommensurate phase, ascribed to the theoretically predicted amplitudon mode. Our work highlights the interaction between the structural dynamics of organic cation CH3NH + 3 and the lead-halide framework, and unravels the competition between tendencies of the organic and inorganic moieties to minimize energy in the incommensurate phase of the hybrid perovskite structure.Organic-inorganic hybrid lead-halide perovskites have emerged as a promising class of new generation photovoltaic materials [1][2][3], showing excellent electronic properties and outstanding power conversion efficiencies [4]. Fundamental insight of the structural dynamics holds the key to understanding their unique electronic properties, and is the subject of intensive theoretical and experimental investigations.[5-10] Methylammonium cation (CH 3 NH + 3 , MA), the most frequently incorporated A site cation in recent photovoltaic applications, possesses a large dipole and exhibits dynamic orientational disorder at room temperature. [11,12] The orientational degrees of freedom of the anisotropic organic cation have been suggested to be responsible for the excellent electronic properties of the hybrid perovskites. [13][14][15]. Yet the inorganic lead-halide framework is the actual optically and electronically active component, on which charge carriers reside. A gap of knowledge exists on how the structural dynamics of MA and lead-halide framework couple with each other despite intensive investigations.In this Letter, we focus on unravelling the interplay between organic MA cations and the inorganic leadhalide framework, and highlight the unique signatures of such coupling. Here we report drastically different phase transformation behaviors between hybrid and inorganic lead-halide perovskites. Using low-frequency Raman scattering, we observe that there is an intermediate structural phase in CH 3 NH 3 PbBr 3 between the orthorhombic and tetragonal phases. With single-crystal X-ray diffraction, we conclude that the intermediate state to be an incommensurate phase, and we follow the evolution of the incommensurate modulation wave vector as * mpimenta@fisica.ufmg.br a function of temperature. A newly activated Raman mode of the incommensurate phase is assigned to the vibration in the amplitude of the structural modulation (...

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All‐Inorganic Perovskite Nanocrystals for High‐Efficiency Light Emitting Diodes: Dual‐Phase CsPbBr₃‐CsPb₂Br₅ Composites

Zhang

et al. 2016

Adv Funct Materials

448

372

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A dual‐phase all‐inorganic composite CsPbBr3‐CsPb2Br5 is developed and applied as the emitting layer in LEDs, which exhibited a maximum luminance of 3853 cd m–2, with current density (CE) of ≈8.98 cd A–1 and external quantum efficiency (EQE) of ≈2.21%, respectively. The parasite of secondary phase CsPb2Br5 nanoparticles on the cubic CsPbBr3 nanocrystals could enhance the current efficiency by reducing diffusion length of excitons on one side, and decrease the trap density in the band gap on the other side. In addition, the introduction of CsPb2Br5 nanoparticles could increase the ionic conductivity by reducing the barrier against the electronic and ionic transport, and improve emission lifetime by decreasing nonradiative energy transfer to the trap states via controlling the trap density. The dual‐phase all‐inorganic CsPbBr3‐CsPb2Br5 composite nanocrystals present a new route of perovskite material for advanced light emission applications.

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Structural Phase Transitions in CsPbBr₃

Cited by 271 publications

References 15 publications

Disordered Configuration of Methylammonium of CH₃NH₃PbBr₃Determined by Single Crystal Neutron Diffractometry

Disordered Configuration of Methylammonium of CH₃NH₃PbBr₃Determined by Single Crystal Neutron Diffractometry

Interplay between organic cations and inorganic framework and incommensurability in hybrid lead-halide perovskite CH3NH3PbBr3

All‐Inorganic Perovskite Nanocrystals for High‐Efficiency Light Emitting Diodes: Dual‐Phase CsPbBr₃‐CsPb₂Br₅ Composites

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Structural Phase Transitions in CsPbBr3

Cited by 271 publications

References 15 publications

Disordered Configuration of Methylammonium of CH3NH3PbBr3Determined by Single Crystal Neutron Diffractometry

Disordered Configuration of Methylammonium of CH3NH3PbBr3Determined by Single Crystal Neutron Diffractometry

Interplay between organic cations and inorganic framework and incommensurability in hybrid lead-halide perovskite CH3NH3PbBr3

All‐Inorganic Perovskite Nanocrystals for High‐Efficiency Light Emitting Diodes: Dual‐Phase CsPbBr3‐CsPb2Br5 Composites

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Structural Phase Transitions in CsPbBr₃

Disordered Configuration of Methylammonium of CH₃NH₃PbBr₃Determined by Single Crystal Neutron Diffractometry

Disordered Configuration of Methylammonium of CH₃NH₃PbBr₃Determined by Single Crystal Neutron Diffractometry

All‐Inorganic Perovskite Nanocrystals for High‐Efficiency Light Emitting Diodes: Dual‐Phase CsPbBr₃‐CsPb₂Br₅ Composites