How Lattice and Charge Fluctuations Control Carrier Dynamics in Halide Perovskites

Mayers, Matthew Z.; Tan, Liang Z.; Egger, David; Rappe, Andrew M.; Reichman, David R.

doi:10.1021/acs.nanolett.8b04276

Cited by 127 publications

(138 citation statements)

References 44 publications

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“…[124] Theoretical models clearly need to take the dynamic fluctuations of HaPs fully into account. As has been shown recently by some of us, [161] Furthermore, recent results and analysis on the emission Stokes shift in HaPs point to similar conclusions: [162] while the optical phonon energy of CsPbBr3 is similar to that of CdTe, and thus the phonon occupation at RT is essentially the same, the T-dependence of the Stokes shift in hybrid and all-inorganic HaPs cannot be explained within a purely harmonic phonon model, in contrast to what is the case for CdTe.…”

Section: Charge-carrier Scattering and Mobilitiessupporting

confidence: 52%

What Remains Unexplained about the Properties of Halide Perovskites?

et al. 2018

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The notion that halide perovskite crystals (ABX , where X is a halide) exhibit unique structural and optoelectronic behavior deserves serious scrutiny. After decades of steady and half a decade of intense research, the question which attributes of these materials are unusual, is discussed, with an emphasis on the identification of the most important remaining issues. The goal is to stimulate discussion rather than to merely present a community consensus.

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Section: Charge-carrier Scattering and Mobilitiessupporting

confidence: 52%

What Remains Unexplained about the Properties of Halide Perovskites?

et al. 2018

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“…27 Notably, this is in agreement with previous findings, which studied the nuclear motion contributing to the central peak in the CsPbBr3 Raman spectrum 16 and quantified the correlation length of the disorder potential in MAPbI3 using classical MD. 37 The presence of such a shortrange correlated disorder potential in HaPs is peculiar since strongly anharmonic nuclear motions and disorder effects were reported for these systems at room temperature, [13][14][15][16][17][18][19][20][21][22][23][24][25] which may be suspected to perturb the electronic disorder in a profound way.…”

Section: Discussionmentioning

confidence: 99%

Dynamic shortening of disorder potentials in anharmonic halide perovskites

Gehrmann

Egger

2019

Nat Commun

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Halide perovskites are semiconductors that exhibit sharp optical absorption edges and small Urbach energies allowing for efficient collection of sunlight in thin-film photovoltaic devices. However, halide perovskites also exhibit large nuclear anharmonic effects and disorder, which is unusual for efficient optoelectronic materials and difficult to rationalize in view of the small Urbach energies that indicate a low amount of disorder. To address this important issue, the disorder potential induced for electronic states by the nuclear dynamics in various paradigmatic halide perovskites is studied with molecular dynamics and density functional theory. We find that the disorder potential is dynamically shortened due to the nuclear motions in the perovskite, such that it is short-range correlated, which is shown to lead to favorable distributions of band edge energies. This dynamic mechanism allows for sharp optical absorption edges and small Urbach energies, which are highly desired properties of any solar absorber material.

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“…This approach has been successfully applied to the 3D HOIPs, in order to study a variety of effects including the Rashba splitting, 25,26 the dependence of electronic properties on the atomic structure, 27,30 and dynamic properties. 31 The parameters of our tight-binding model are determined from a single DFT calculation on the cubic crystal structure; for simplicity, we perform calculations on CsPbI 3 , whose lattice constant is very similar to that of cubic MAPbI 3 and NH 4 PbI 3 (all between 6.2 − 6.3 Å). DFT calculations were performed using Quantum Espresso 32 with the PBE exchange correlation functional 33 and tight-binding matrix elements were determined using the Wannier90 code.…”

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confidence: 99%

Optical Properties of Layered Hybrid Organic–Inorganic Halide Perovskites: A Tight-Binding GW-BSE Study

Cho

Berkelbach

2019

J. Phys. Chem. Lett.

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We present a many-body calculation of the band structure and optical spectrum of the layered hybrid organicinorganic halide perovskites in the Ruddlesden-Popper phase with the general formula A 2 A n−1 M n X 3n+1 , focusing specifically on the lead iodide family. We calculate the mean-field band structure with spin-orbit coupling, quasiparticle corrections within the GW approximation, and optical spectra using the Bethe-Salpeter equation. The model is parameterized by first-principles calculations and classical electrostatic screening, enabling an accurate but cost-effective study of large unit cells and corresponding thickness-dependent properties. A transition of the electronic and optical properties from quasi-two-dimensional behavior to three-dimensional behavior is shown for increasing n and the nonhydrogenic character of the excitonic Rydberg series is analyzed. The thickness-dependent 1s and 2s exciton energy levels are in good agreement with recently reported experiments and the 1s exciton binding energy is calculated to be 302 meV for n = 1, 97 meV for n = 5, and 37 meV for n = ∞ (bulk MAPbI 3 ).Hybrid organic-inorganic perovskites (HOIPs) are promising photovoltaic materials, most recently showing a high power conversion efficiency of over 24%. 1 A three dimensional bulk HOIP AMX 3 can be transformed into a layered HOIP in the Ruddlesden-Popper phase A 2 A n−1 M n X 3n+1 by substituting a small organic cation A + by a bulkier one A + .Common choices for the small organic cation are A + =CH 3 NH + 3 , NH + 4 ; for the bulkier cation are A + =C 4 H 9 NH + 3 , C 6 H 5 C 2 H 4 NH + 3 ; for the metal are M 2+ =Sn 2+ , Pb 2+ ; and for the halide are X − =Cl − , I − , Br − . A major drawback of the 3D HOIPs for photovoltaics is their relatively fast degradation when exposed to air, moisture, and light; in contrast, the layered HOIPs are more stable while maintaining high power conversion efficiencies under working conditions. 2,3 The optical properties of layered HOIPs can also be easily controlled by composition, 4 enhancing their flexibility for a variety of optoelectronic applications. Unlike the van der Waals materials -a prototypical family of layered materials including graphene, hexagonal boron nitride, and the transition-metal dichalcogenides -the layered HOIPs have sublayers that are covalently bonded. This distinct property makes the layered HOIPs an insightful mixeddimensional platform for investigating the transition of optoelectronic properties from two dimensional to three dimensional.The n-dependent properties of layered HOIPs have been experimentally investigated, especially during the last five years, 5-9 including mechanically exfoliated thin sheets of a layered HOIP. 10,11 Early theoretical investigations of the optical properties of layered HOIPs were performed using the effective mass approximation, giving good estimates for the exciton binding energy and a qualitative explanation of the essential physics. 5,12-14 For a quantitative analysis, ab initio approaches such as density functional...

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How Lattice and Charge Fluctuations Control Carrier Dynamics in Halide Perovskites

Cited by 127 publications

References 44 publications

What Remains Unexplained about the Properties of Halide Perovskites?

What Remains Unexplained about the Properties of Halide Perovskites?

Dynamic shortening of disorder potentials in anharmonic halide perovskites

Optical Properties of Layered Hybrid Organic–Inorganic Halide Perovskites: A Tight-Binding GW-BSE Study

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