Dielectric study of CH3NH3PbX3 (X = Cl, Br, I)

Onoda-Yamamuro, Noriko; Matsuo, Takasuke; Suga, Hiroshi

doi:10.1016/0022-3697(92)90121-s

Cited by 379 publications

(473 citation statements)

References 10 publications

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“…71 This glassy freezing of dipolar motion on cooling is in accordance with our prior report, 14 and in contrast with the abrupt loss of dipolar motion observed in dielectric measurements of MAPbI 3 at the β-γ transition. 14,17,18,20 Calorimetry about the motional freezing temperature reveals two closely spaced peaks in the heat capacity, C p , with a total transition entropy too small to be that of an abrupt order-disorder transition (details in the supporting information, Figure S2), suggesting a gradual loss of motion precedes the phase transition on cooling.…”

Section: Resultsmentioning

confidence: 99%

“…Since the first preparation of the hybrid lead halide perovskites, 12 the behavior of the molecular cations has been studied by calorimetry, 13,14 infrared spectroscopy, 13,15,16 dielectric spectroscopy, 14,[17][18][19][20] Raman spectroscopy, 21 quasi-elastic and inelastic neutron scattering, [22][23][24][25][26] nuclear magnetic resonance (NMR) spectroscopy, [27][28][29][30][31][32] isotopic substitution, 33 and ab initio methods, [34][35][36][37][38][39] and these findings have been correlated to the structure evolution from crystallographic techniques. 19,[40][41][42][43][44][45][46] Most of these efforts have focused on MAPbX 3…”

Section: Introductionmentioning

confidence: 99%

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Universal Dynamics of Molecular Reorientation in Hybrid Lead Iodide Perovskites

et al. 2017

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The role of organic molecular cations in the high-performance perovskite photovoltaic absorbers, methylammonium lead iodide (MAPbI 3 ) and formamidinium lead iodide (FAPbI 3 ), has been an enigmatic subject of great interest. Beyond aiding in the ease of processing of thin films for photovoltaic devices, there have been suggestions that many of the remarkable properties of the halide perovskites can be attributed to the dipolar nature and the dynamic behavior of these cations. Here, we establish the dynamics of the molecular cations in FAPbI 3 between 4 K and 340 K and the nature of their interaction with the surrounding inorganic cage using a combination of solid state nuclear magnetic resonance and dielectric spectroscopies, neutron scattering, calorimetry, and ab initio calculations. Detailed comparisons of the reported temperature dependence of the dynamics of MAPbI 3 are then carried out which reveal the molecular ions in the two different compounds to exhibit very similar rotation rates (≈8 ps) at room temperature, despite differences in other temperature regimes.For FA, rotation about the N···N axis, which reorients the molecular dipole, is the dominant motion in all phases, with an activation barrier of ≈21 meV in the ambient phase, compared to ≈110 meV for the analogous dipole reorientation of MA. Geometrical frustration of the molecule-cage interaction in FAPbI 3 produces a disordered γ-phase and subsequent glassy freezing at yet lower temperatures. Hydrogen bonds suggested by atom-atom distances from neutron total scattering experiments imply a substantial role for the molecules in directing structure and dictating properties. The temperature dependence of reorientation of the dipolar molecular cations systematically described here can clarify various hypotheses including large-polaron charge transport and fugitive electron spin polarization that have been invoked in the context of these unusual materials.2

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Universal Dynamics of Molecular Reorientation in Hybrid Lead Iodide Perovskites

et al. 2017

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“…CH 3 NH 3 PbI 3 exhibits three crystallographic phases. [28] At room temperature, the tetragonal phase (I4/mcm) of CH 3 NH 3 PbI 3 is thermodynamically the most stable phase, and transforms into the orthorhombic phase (Pnma) below 160 K, whereas above 330 K, CH 3 NH 3 PbI 3 stabilizes into a cubic phase (Pm3m). [29] The reciprocal space maps of both The spin-coated sample has clearly a preferred orientation with the 110 plane aligned at 36° (FWHM: 22°) relative to the surface plane.…”

Section: Structural Characterizationmentioning

confidence: 99%

Function Follows Form: Correlation between the Growth and Local Emission of Perovskite Structures and the Performance of Solar Cells

Dar

Hinderhofer

Jacopin

et al. 2017

Adv Funct Materials

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Understanding the relation between the growth and local emission of hybrid perovskite structures, and the performance of the devices based on them demands attention. In this study, we have investigated the local structural and emission features of CH 3 NH 3 PbI 3 , CH 3 NH 3 PbBr 3 and CH(NH 2 ) 2 PbBr 3 perovskite films deposited under different yet optimized conditions using X-ray scattering and cathodoluminescence spectroscopy, respectively. X-ray scattering shows that CH 3 NH 3 PbI 3 film involving spin coating of CH 3 NH 3 I instead of dipping is composed of perovskite structures exhibiting a preferred orientation with [202] direction perpendicular to the surface plane. The device based on the CH 3 NH 3 PbI 3 film composed of oriented crystals yield a higher photovoltage. In case of CH 3 NH 3 PbBr 3 , while the crystallinity decreases when the HBr solution is used in a single-step method, the photovoltage enhancement from 1.1 to 1.46 V seems largely stemming from the morphological improvements, i.e. a better connection between the crystallites due to a higher nucleation 2 density. Furthermore, a high photovoltage of 1.47 V obtained from CH(NH 2 ) 2 PbBr 3 devices could be attributed to the formation of perovskite films displaying uniform cathodoluminescence emission. The comparative analysis of the local structural, morphological, and emission characteristics of the different perovskite films support the higher photovoltage yielded by the relatively better performing devices.

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“…Previous studies have not come to unique results on this point. While dielectric measurements of CH 3 NH 3 PbI 3 crystals only reveal a hysteresis of a few kelvin, 29 resistivity measurements -also on crystals -exhibit a span of about 30 K between the corresponding features in the heating and the cooling cycle. 4 We proceed by analyzing PL emission recorded in identical cooling-and heating cycles as performed for optical absorption measurements.…”

mentioning

confidence: 96%

“…26 The behavior of the "A-cation" CH 3 NH 3 + , which, other than in purely inorganic perovskites, possesses several rotational degrees of freedom in the high-temperature phase, has been investigated by means of NMR-spectroscopy 27 as well as IR-vibrational spectroscopy, 28 calorimetry, 28 and dielectric measurements. 24,29 It was found that the cubic symmetry of the high-temperature phase is effectively preserved through rapid random reorientations of the CH 3 NH 3 + -cation. From its 24 possible orientations, 8 remain in the tetragonal phase.…”

mentioning

confidence: 99%

Charge carrier recombination channels in the low-temperature phase of organic-inorganic lead halide perovskite thin films

et al. 2014

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The optoelectronic properties of the mixed hybrid lead halide perovskite CH3NH3PbI3−xClx have been subject to numerous recent studies related to its extraordinary capabilities as an absorber material in thin film solar cells. While the greatest part of the current research concentrates on the behavior of the perovskite at room temperature, the observed influence of phonon-coupling and excitonic effects on charge carrier dynamics suggests that low-temperature phenomena can give valuable additional insights into the underlying physics. Here, we present a temperature-dependent study of optical absorption and photoluminescence (PL) emission of vapor-deposited CH3NH3PbI3−xClx exploring the nature of recombination channels in the room- and the low-temperature phase of the material. On cooling, we identify an up-shift of the absorption onset by about 0.1 eV at about 100 K, which is likely to correspond to the known tetragonal-to-orthorhombic transition of the pure halide CH3NH3PbI3. With further decreasing temperature, a second PL emission peak emerges in addition to the peak from the room-temperature phase. The transition on heating is found to occur at about 140 K, i.e., revealing significant hysteresis in the system. While PL decay lifetimes are found to be independent of temperature above the transition, significantly accelerated recombination is observed in the low-temperature phase. Our data suggest that small inclusions of domains adopting the room-temperature phase are responsible for this behavior rather than a spontaneous increase in the intrinsic rate constants. These observations show that even sparse lower-energy sites can have a strong impact on material performance, acting as charge recombination centres that may detrimentally affect photovoltaic performance but that may also prove useful for optoelectronic applications such as lasing by enhancing population inversion.

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Dielectric study of CH3NH3PbX3 (X = Cl, Br, I)

Cited by 379 publications

References 10 publications

Universal Dynamics of Molecular Reorientation in Hybrid Lead Iodide Perovskites

Universal Dynamics of Molecular Reorientation in Hybrid Lead Iodide Perovskites

Function Follows Form: Correlation between the Growth and Local Emission of Perovskite Structures and the Performance of Solar Cells

Charge carrier recombination channels in the low-temperature phase of organic-inorganic lead halide perovskite thin films

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