Structural Study on Cubic–Tetragonal Transition of CH3NH3PbI3

Kawamura, Yukihiko; Mashiyama, Hiroyuki; Hasebe, K.

doi:10.1143/jpsj.71.1694

Cited by 490 publications

(514 citation statements)

References 7 publications

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“…Figure 1b shows that the band structure obtained within this approximation is in good agreement with that from a complete calculation. The removal of the cation is especially useful since it eliminates the complications associated with the observed orientational disorder 13,17,28,29 . Another important observation can be made by inspecting X-ray diffraction data, as reported for example in ref.…”

Section: Resultsmentioning

confidence: 99%

Steric engineering of metal-halide perovskites with tunable optical band gaps

et al. 2014

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Owing to their high energy-conversion efficiency and inexpensive fabrication routes, solar cells based on metal-organic halide perovskites have rapidly gained prominence as a disruptive technology. An attractive feature of perovskite absorbers is the possibility of tailoring their properties by changing the elemental composition through the chemical precursors. In this context, rational in silico design represents a powerful tool for mapping the vast materials landscape and accelerating discovery. Here we show that the optical band gap of metal-halide perovskites, a key design parameter for solar cells, strongly correlates with a simple structural feature, the largest metal-halide-metal bond angle. Using this descriptor we suggest continuous tunability of the optical gap from the mid-infrared to the visible. Precise band gap engineering is achieved by controlling the bond angles through the steric size of the molecular cation. On the basis of these design principles we predict novel low-gap perovskites for optimum photovoltaic efficiency, and we demonstrate the concept of band gap modulation by synthesising and characterising novel mixed-cation perovskites.

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Section: Resultsmentioning

confidence: 99%

Steric engineering of metal-halide perovskites with tunable optical band gaps

et al. 2014

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“…At elevated temperature, the PbI 6 octahedra of the inorganic host undergo large tilt-mode oscillations relative to their average positions in the ideal cubic structure, 10 while the molecular cations rotate rapidly. 11,12 Distortions of the inorganic lattice by halide substitution and octahedral tilting have been shown to influence the band gap and absorption properties.…”

Section: Introductionmentioning

confidence: 99%

Energy Landscape of Molecular Motion in Cubic Methylammonium Lead Iodide from First-Principles

2016

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Molecular A-cation dynamics are known to play a role in the electronic properties and structure of hybrid organic-inorganic ABX 3 perovskites such as CH 3 NH 3 PbI 3 .We calculate the full energy landscape for rigid-body rotations and translations of the methylammonium cation in the cubic phase of CH 3 NH 3 PbI 3 . Energy barriers are calculated for combinations of molecular reorientation, on-axis rotation, and molecular translation within the unit cell. Allowing molecular translations significantly stabilizes orientations along [100] which we attribute to strong N−H· · · I interactions between CH 3 NH 3 + and the inorganic Pb−I host lattice.

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“…The resulting unit cell is tetragonal with space group I4cm and has doubled in volume with respect to the cubic unit cell. 24,25 A further transition to an orthorhombic phase is observed at ∼160 K. 24,26 This transition is accompanied by a tilting of the PbI 6 -octahedra out of the ab-plane and a corresponding further doubling of the unit cell volume (space group Pnma). 26 An analysis of the symmetries of the tetragonal and the orthorhombic phases shows that a continuous transition between the two space groups is not possible.…”

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confidence: 99%

“…At temperatures above ∼330 K, the compound adopts the simple cubic perovskite structure (space group Pm3m), 23 although a very small ferroelectric-type displacement of the lead-cation has been observed, 4 which -strictly speaking -creates a tetragonal unit cell (space group P4mm). The transition to the room-temperature phase involves a collective rotation of the PbI 6 -octahedra around the c-axis, 24,25 which is well-known from many inorganic perovskites and which leads to closer packing within the ab-plane. The resulting unit cell is tetragonal with space group I4cm and has doubled in volume with respect to the cubic unit cell.…”

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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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Structural Study on Cubic–Tetragonal Transition of CH₃NH₃PbI₃

Cited by 490 publications

References 7 publications

Steric engineering of metal-halide perovskites with tunable optical band gaps

Steric engineering of metal-halide perovskites with tunable optical band gaps

Energy Landscape of Molecular Motion in Cubic Methylammonium Lead Iodide from First-Principles

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

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