Structure and surface properties of size-tuneable CsPbBr<sub>3</sub> nanocrystals

Hooper, Thomas J. N.; Fang, Yanan; Brown, Alasdair A. M.; Pu, Suan Hui; White, Tim

doi:10.1039/d1nr04602k

Cited by 7 publications

(13 citation statements)

References 61 publications

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“…Such a surface structure requires charge balance from cationic ligands. Hence, halide ion‐containing ligands are desirable and preferred [15] . Up to now, the available organic cations are very limited, and most of them are nitrogen‐containing.…”

Section: Introductionmentioning

confidence: 99%

Organic Sulfonium‐Stabilized High‐Efficiency Cesium or Methylammonium Lead Bromide Perovskite Nanocrystals

Cai

Tian

et al. 2022

Angew Chem Int Ed

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Herein, we report a new X-type ligand, i.e., organic sulfonium bromide, for high-efficiency CsPbBr 3 and MAPbBr 3 (MA = methylammonium) perovskite nanocrystals (PNCs). We first confirmed the facile synthesis of the titled ligands in N,N-dimethylformamide at room temperature. By reacting dodecylmethylsulfide with allyl bromide, (3-bromopropyl)trimethoxysilane, and 1,4-dibromobutane, respectively, three representative ligands (named DAM, DSM, and DMM) are acquired. All of them result in CsPbBr 3 and MAPbBr 3 PNCs with near-unity photoluminescence quantum yield (PLQY) and decent ambient stability (no less than 90 % PLQY after 2 months) using a room-temperature ligand-assisted reprecipitation technique. Among them, DSM and DMM endow CsPbBr 3 PNCs with higher thermal/light stability arising from the cross-linkable or bidentate ligand structure. Further, DSM-CsPbBr 3 PNCs can be incorporated into polystyrene through in situ thermal polymerization and the composite shows a record-high PLQY of 93.8 %.

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Section: Introductionmentioning

confidence: 99%

Organic Sulfonium‐Stabilized High‐Efficiency Cesium or Methylammonium Lead Bromide Perovskite Nanocrystals

Cai

Tian

et al. 2022

Angew Chem Int Ed

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“…Nuclear magnetic resonance (NMR) is well suited to establish an atomic-level understanding of both the organic and inorganic components of hybrid perovskites, as well as dopants and additives. − Specifically, magic angle spinning (MAS) NMR has previously been applied to study cation incorporation, − phase segregation, ,− cation dynamics, − passivating layers, , degradation, , and phase transitions. − NMR has also been successful in probing bulk layered perovskites, ,, bulk 2D/3D perovskite heterostructures, − and the surfaces of perovskite nanocrystals. − However, the intrinsic insensitivity of NMR limits its utility to study thin-film samples as used in perovskite devices, owing to the very low sample mass. This insensitivity is compounded for the study of dopants and additives, which comprise only a small fraction of the sample.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Nuclear Polarization Enables NMR of Surface Passivating Agents on Hybrid Perovskite Thin Films

et al. 2022

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Surface and bulk molecular modulators are the key to improving the efficiency and stability of hybrid perovskite solar cells. However, due to their low concentration, heterogeneous environments, and low sample mass, it remains challenging to characterize their structure and dynamics at the atomic level, as required to establish structure–activity relationships. Nuclear magnetic resonance (NMR) spectroscopy has revealed a wealth of information on the atomic-level structure of hybrid perovskites, but the inherent insensitivity of NMR severely limits its utility to characterize thin-film samples. Dynamic nuclear polarization (DNP) can enhance NMR sensitivity by orders of magnitude, but DNP methods for perovskite materials have so far been limited. Here, we determined the factors that limit the efficiency of DNP NMR for perovskite samples by systematically studying layered hybrid perovskite analogues. We find that the fast-relaxing dynamic cation is the major impediment to higher DNP efficiency, while microwave absorption and particle morphology play a secondary role. We then show that the former can be mitigated by deuteration, enabling 1H DNP enhancement factors of up to 100, which can be harnessed to enhance signals from dopants or additives present in very low concentrations. Specifically, using this new DNP methodology at a high magnetic field and with small sample volumes, we have recorded the NMR spectrum of the 20 nm (6 μg) passivating layer on a single perovskite thin film, revealing a two-dimensional (2D) layered perovskite structure at the surface that resembles the n = 1 homologue but which has greater disorder than in bulk layered perovskites.

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“…The Brownian tumbling of the NCs in their colloidal state not only affects the shape of their 133 Cs NMR signals but also their relaxation times. The transition from bulk CsPbBr 3 to CsPbBr 3 NCs in ssNMR leads to a decimation of T 1 , from over 100 s to 4–24 s, for 6–13 nm sized NCs, induced by a larger distribution of local environments, leading to enhanced spin–lattice relaxation . This was supported by the observation of even faster T 1 relaxation times for surface or near-surface species compared to the inner core signals.…”

Section: Colloidal Nmr On Ncsmentioning

confidence: 85%

“…The Brownian tumbling of the NCs in their colloidal state not only affects the shape of their 133 Cs NMR signals but also their relaxation times. The transition from bulk CsPbBr 3 to CsPbBr 3 NCs in ssNMR leads to a decimation of T 1 , from over 100 s to 4−24 s, 25 This was supported by the observation of even faster T 1 relaxation times for surface or near-surface species compared to the inner core signals. In their colloidal state, the T 1 relaxation of NCs is further stimulated by field fluctuation near the Larmor frequency induced by their tumbling and possible solvent interactions, reducing the T 1 times to below 4 s, even for 11 nm sized particles (Figure 2b,f,j).…”

Section: ■ Colloidal Nmr On Ncsmentioning

confidence: 89%

Disorder and Halide Distributions in Cesium Lead Halide Nanocrystals as Seen by Colloidal ¹³³Cs Nuclear Magnetic Resonance Spectroscopy

Aebli,

Kaul,

Yazdani

et al. 2024

Chem. Mater.

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Colloidal nuclear magnetic resonance (cNMR) spectroscopy on inorganic cesium lead halide nanocrystals (CsPbX 3 NCs) is found to serve for noninvasive characterization and quantification of disorder within these structurally soft and labile particles. In particular, we show that 133 Cs cNMR is highly responsive to size variations from 3 to 11 nm or to altering the capping ligands on the surfaces of CsPbX 3 NCs. Distinct 133 Cs signals are attributed to the surface and core NC regions. Increased heterogeneous broadening of 133 Cs signals, observed for smaller NCs as well as for long-chain zwitterionic capping ligands (phosphocholines, phosphoethanol-(propanol)amine, and sulfobetaines), can be attributed to more significant surface disorder and multifaceted surfaces (truncated cubes). On the contrary, capping with dimethyldidodecylammonium bromide (DDAB) successfully reduces signal broadening owing to better surface passivation and sharper (001)-bound cuboid shape. DFT calculations on various sizes of NCs corroborate the notion that the surface disorder propagates over several octahedral layers. 133 Cs NMR is a sensitive probe for studying halide gradients in mixed Br/Cl NCs, indicating bromide-rich surfaces and chloride-rich cores. On the contrary, mixed Br/I NCs exhibit homogeneous halide distributions.

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Structure and surface properties of size-tuneable CsPbBr₃ nanocrystals

Abstract: This investigation has characterised the structure and surface chemistry of CsPbBr3 nanocrystals with controlled diameters between 6.4 to 12.8 nm. The nanocrystals were investigated via a thorough 133Cs solid state...

Cited by 7 publications

References 61 publications

Organic Sulfonium‐Stabilized High‐Efficiency Cesium or Methylammonium Lead Bromide Perovskite Nanocrystals

Organic Sulfonium‐Stabilized High‐Efficiency Cesium or Methylammonium Lead Bromide Perovskite Nanocrystals

Dynamic Nuclear Polarization Enables NMR of Surface Passivating Agents on Hybrid Perovskite Thin Films

Disorder and Halide Distributions in Cesium Lead Halide Nanocrystals as Seen by Colloidal ¹³³Cs Nuclear Magnetic Resonance Spectroscopy

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Structure and surface properties of size-tuneable CsPbBr3 nanocrystals

Abstract: This investigation has characterised the structure and surface chemistry of CsPbBr3 nanocrystals with controlled diameters between 6.4 to 12.8 nm. The nanocrystals were investigated via a thorough 133Cs solid state...

Cited by 7 publications

References 61 publications

Organic Sulfonium‐Stabilized High‐Efficiency Cesium or Methylammonium Lead Bromide Perovskite Nanocrystals

Organic Sulfonium‐Stabilized High‐Efficiency Cesium or Methylammonium Lead Bromide Perovskite Nanocrystals

Dynamic Nuclear Polarization Enables NMR of Surface Passivating Agents on Hybrid Perovskite Thin Films

Disorder and Halide Distributions in Cesium Lead Halide Nanocrystals as Seen by Colloidal 133Cs Nuclear Magnetic Resonance Spectroscopy

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Product

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Structure and surface properties of size-tuneable CsPbBr₃ nanocrystals

Disorder and Halide Distributions in Cesium Lead Halide Nanocrystals as Seen by Colloidal ¹³³Cs Nuclear Magnetic Resonance Spectroscopy