Influence of hidden halogen mobility on local structure of CsSn(Cl1−xBrx)3 mixed-halide perovskites by solid-state NMR

Karmakar, Abhoy; Bhattacharya, Amit; Sarkar, Diganta; Bernard, Guy M.; Mar, Arthur; Michaelis, Vladimir K.

doi:10.1039/d0sc05614f

Cited by 40 publications

(91 citation statements)

References 77 publications

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“…For instance, Snbased MHPs oen degrade within minutes of ambient exposure, for which acquisition of multidimensional ssNMR experiments is less straightforward. 185,312,313 Acceleration of acquisition times for ssNMR experiments, particularly for masslimited samples such as thin lms, have been pivotal for the characterization of MHPs. 314 The length scales of physical interactions in MHP devices span from the unit-cell ( A) scale to many cm.…”

Section: Length and Timescales Of Physical Processesmentioning

confidence: 99%

“…The environmental stability and degradation processes of a wide variety of 3D MHPs have been investigated by multinuclear ( 1 H, 207 Pb, 119 Sn, 133 Cs) ssNMR spectroscopy techniques. 312,313,359,367,368 The hydrothermal stability and degradation of MAPbI 3 has been characterized through 1D 207 Pb NMR spectroscopy, and revealed that pristine MAPbI 3 and its degradation products, MAPbI 3 $H 2 O, and PbI 2 , have distinct chemical shis (Fig. 7a).…”

Section: Cations Anions and Degradation Products In 3d Mhpsmentioning

confidence: 99%

“…In tin-based MHPs, 119 Sn ssNMR has been applied to probe the mixing of halides and local dynamics of [SnX 6 ] 4À sites. 312,313 Longitudinal relaxation times (T 1 ) of 119 Sn sites in tin-based MHPs span 6 orders of magnitudes owing to the presence of different relaxation mechanisms depending on the halide composition. For example, in tin halides, the 119 Sn T 1 is determined by the strength of the 119 Sn-X scalar couplings, which is as follows: 1 J Sn-I > 1 J Sn-Br > 1 J Sn-Cl .…”

Section: Mhp Nanoparticlesmentioning

confidence: 99%

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Interfaces in metal halide perovskites probed by solid-state NMR spectroscopy

2021

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Section: Length and Timescales Of Physical Processesmentioning

confidence: 99%

Section: Cations Anions and Degradation Products In 3d Mhpsmentioning

confidence: 99%

Section: Mhp Nanoparticlesmentioning

confidence: 99%

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Interfaces in metal halide perovskites probed by solid-state NMR spectroscopy

2021

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“…133 Cs sensitivity towards variations in the local environment is also exploited in NMR analysis of lead-free perovskites [ 83 ]. The transition from the cubic to the monoclinic phase for CsSnCl 3 is easily monitored over time, as the 133 Cs NMR resonance of the two forms differs in position and linewidth ( Figure 3 b).…”

Section: Bulk Perovskitesmentioning

confidence: 99%

The Contribution of NMR Spectroscopy in Understanding Perovskite Stabilization Phenomena

Aiello

Masi

2021

Nanomaterials

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Although it has been exploited since the late 1900s to study hybrid perovskite materials, nuclear magnetic resonance (NMR) spectroscopy has only recently received extraordinary research attention in this field. This very powerful technique allows the study of the physico-chemical and structural properties of molecules by observing the quantum mechanical magnetic properties of an atomic nucleus, in solution as well as in solid state. Its versatility makes it a promising technique either for the atomic and molecular characterization of perovskite precursors in colloidal solution or for the study of the geometry and phase transitions of the obtained perovskite crystals, commonly used as a reference material compared with thin films prepared for applications in optoelectronic devices. This review will explore beyond the current focus on the stability of perovskites (3D in bulk and nanocrystals) investigated via NMR spectroscopy, in order to highlight the chemical flexibility of perovskites and the role of interactions for thermodynamic and moisture stabilization. The exceptional potential of the vast NMR tool set in perovskite structural characterization will be discussed, aimed at choosing the most stable material for optoelectronic applications. The concept of a double-sided characterization in solution and in solid state, in which the organic and inorganic structural components provide unique interactions with each other and with the external components (solvents, additives, etc.), for material solutions processed in thin films, denotes a significant contemporary target.

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“…12,13 The tin(II) halide perovskites ASnX3 are possible alternatives with lower toxicity, but they exhibit lower PCE of up to 10% and rapidly oxidize in air (Sn 2+ to Sn 4+ ). [14][15][16][17] Vacancy-ordered double perovskites A2BX6 (A = Cs + , CH3NH3 + , CH(NH2)2 + ; B = Sn 4+ ; X = Cl − , Br − , I − ) are an alternative family of perovskites, demonstrating much higher ambient stability and lower toxicity. 18 The structure of A2BX6 can be described as an ABX3 perovskite, with half of the Bsites removed in an ordered fashion (Figure 1a).…”

Section: Introductionmentioning

confidence: 99%

Uncovering Halide Mixing and Octahedral Dynamics in Vacancy-Ordered Double Perovskites by Multinuclear Magnetic Resonance Spectroscopy

Karmakar¹,

S²,

P³

et al. 2021

Preprint

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Vacancy-ordered double perovskites Cs2SnX6 (X = Cl, Br, I) have emerged as promising lead-free and ambient-stable materials for photovoltaic and optoelectronic applications. To advance these promising materials, it is crucial to determine the correlations between physical properties and their local structure and dynamics. Solid-state NMR spectroscopy of multiple NMR-active nuclei (133Cs, 119Sn and 35Cl) in these cesium tin(IV) halides has been used to decode the structure, which plays a key role in the materials’ optical properties. The 119Sn NMR chemical shifts span approximately 4000 ppm and the 119Sn spin-lattice relaxation times span three orders of magnitude when the halogen goes from chlorine to iodine in these diamagnetic compounds. Moreover, ultrawideline 35Cl NMR spectroscopy for Cs2SnCl6 indicates an axially symmetric chlorine electric field gradient tensor with a large quadrupolar coupling constant of ca. 32 MHz, suggesting a chlorine that is directly attached to Sn(IV) ions. Variable temperature 119Sn spin lattice relaxation time measurements uncover the presence of hidden dynamics of octahedral SnI6 units in Cs2SnI6 with a low activation energy barrier of 12.45 kJ/mol (0.129 eV). We further show that complete mixed-halide solid solutions of Cs2SnClxBr6−x and Cs2SnBrxI6−x (0 ≤ x ≤ 6) form at any halogen compositional ratio. 119Sn and 133Cs NMR spectroscopy resolve the unique local SnClnBr6−nand SnBrnI6−n (n = 0−6) octahedral and CsBrmI12−m (m = 0−12) cuboctahedral environments in the mixed-halide samples. The experimentally observed 119Sn NMR results are consistent with magnetic shielding parameters obtained by density functional theory computations to verify random halogen distribution in mixed-halide analogues. Finally, we demonstrate the difference in the local structures and optical absorption properties of Cs2SnI6 samples prepared by solvent-assisted and solvent-free synthesis routes.

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Influence of hidden halogen mobility on local structure of CsSn(Cl_1−xBr_x)₃ mixed-halide perovskites by solid-state NMR

Abstract: Unravelling the atomic-level chemical structure, slow phase conversion or degradation pathways and rapid halogen hopping of cesium tin(ii) halide perovskites using solid-state 119Sn and 133Cs NMR spectroscopy.

Cited by 40 publications

References 77 publications

Interfaces in metal halide perovskites probed by solid-state NMR spectroscopy

Interfaces in metal halide perovskites probed by solid-state NMR spectroscopy

The Contribution of NMR Spectroscopy in Understanding Perovskite Stabilization Phenomena

Uncovering Halide Mixing and Octahedral Dynamics in Vacancy-Ordered Double Perovskites by Multinuclear Magnetic Resonance Spectroscopy

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