Surface Chemistry of Colloidal Semiconductor Nanocrystals: Organic, Inorganic, and Hybrid

Brutchey, Richard L.; Hens, Zeger; Kovalenko, Maksym V.

doi:10.1002/9781118870068.ch7

Cited by 8 publications

(16 citation statements)

References 123 publications

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“…Quantum dot (QD) properties are heavily influenced by the coordination environment of their surface . The ligands coordinated to their surfaces affect both the chemical and colloidal stability of the QDs, in addition to their ensuing electronic structures.…”

Section: Figurementioning

confidence: 99%

“…Abstract: Cesium lead halide perovskites are an emerging class of quantum dots (QDs) that have shown promise in avariety of applications;however,their properties are highly dependent on their surface chemistry.T ot his point, the thermodynamics of ligand binding remain unstudied. Herein, 1 HNMR methods were used to quantify the thermodynamics of ligand exchange on CsPbBr 3 QDs.B oth oleic acid and oleylamine native ligands dynamically interact with the CsPbBr 3 QD surface, having individual surface densities of 1.2-1.7 nm À2 .1 0-Undecenoic acid undergoes an exergonicexchange equilibrium with bound oleate (K eq = 1.97) at 25 8 8Cw hile 10-undecenylphosphonic acid undergoes irreversible ligand exchange.Undec-10en-1-amine exergonically exchanges with oleylamine (K eq = 2.52) at 25 8 8C. Exchange occurs with carboxylica cids,p hosphonic acids,and amines on CsPbBr 3 QDs without etching of the nanocrystal surface;i ncreases in the steady-state PL intensities correlate with more strongly bound conjugate base ligands.…”

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confidence: 99%

“…Quantumdot(QD)propertiesareheavilyinfluencedbythe coordination environment of their surface. [1] Thel igands coordinated to their surfaces affect both the chemical and colloidal stability of the QDs,i na ddition to their ensuing electronic structures.A nu p-and-coming class of QDs is composed of the colloidal lead halide perovskites (APbX 3 , where A = CH 3 NH 3 + ,C H(NH 2 ) 2 + ,C s + ;X = Cl À ,B r À ,I À ) because of their excellent optoelectronic properties,s uch as bright photoluminescence (PL) with narrow spectral linewidths that covers aw ide color gamut. [2][3][4] These properties have made lead halide perovskite QDs intriguing for use in am ultitude of optical devices,s uch as LEDs [5][6][7] and solar cells.…”

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confidence: 99%

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Quantifying the Thermodynamics of Ligand Binding to CsPbBr₃ Quantum Dots

2018

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Cesium lead halide perovskites are an emerging class of quantum dots (QDs) that have shown promise in a variety of applications; however, their properties are highly dependent on their surface chemistry. To this point, the thermodynamics of ligand binding remain unstudied. Herein, H NMR methods were used to quantify the thermodynamics of ligand exchange on CsPbBr QDs. Both oleic acid and oleylamine native ligands dynamically interact with the CsPbBr QD surface, having individual surface densities of 1.2-1.7 nm . 10-Undecenoic acid undergoes an exergonic exchange equilibrium with bound oleate (K =1.97) at 25 °C while 10-undecenylphosphonic acid undergoes irreversible ligand exchange. Undec-10-en-1-amine exergonically exchanges with oleylamine (K =2.52) at 25 °C. Exchange occurs with carboxylic acids, phosphonic acids, and amines on CsPbBr QDs without etching of the nanocrystal surface; increases in the steady-state PL intensities correlate with more strongly bound conjugate base ligands.

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Quantifying the Thermodynamics of Ligand Binding to CsPbBr₃ Quantum Dots

2018

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“…[10][11][12][13][14] For instance, surface ligands play a critical role in passivating mid-gap electronic trap states and enabling high PLQY. 10,11,13,15 Judicious selection of surface ligands can improve stability 16 and improve the quality of lead halide perovskite thin films formed from deposition of QD precursors. 17 Surface reconstruction, as well as ligand absorption-desorption, happen frequently at the surface of colloidal CsPbBr3 QDs due to their intrinsically ionic and highly dynamic nature.…”

Section: Introductionmentioning

confidence: 99%

Surface Termination of CsPbBr₃ Perovskite Quantum Dots Determined by Solid-State NMR Spectroscopy

et al. 2020

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Cesium lead halide perovskite quantum dots (QDs) have gained significant attention as next-generation optoelectronic materials; however, their properties are highly dependent on their surface chemistry. The surfaces of cuboidal CsPbBr3 QDs have been intensively studied by both theoretical and experimental techniques, but fundamental questions still remain about the atomic termination of the QDs. The binding sites and modes of ligands at the surface remain unproven. Herein, we demonstrate that solid-state NMR spectroscopy allows the unambiguous assignments of organic surface ligands via 1H, 13C, and 31P NMR. Surface-selective 133Cs solid-state NMR spectra show the presence of an additional 133Cs NMR signal with a unique chemical shift that is attributed to Cs atoms terminating the surface of the particle and which are likely coordinated by carboxylate ligands. Dipolar dephasing curves that report on the distance between the surface ammonium ligands and Cs and Pb were recorded using double resonance 1H{133Cs} and 1H{207Pb} RESPDOR experiments. Model QD surface slabs with different possible surface terminations were generated from the CsPbBr3 crystal structure and theoretical RESPDOR dipolar dephasing curves considering all possible 1H-133Cs/207Pb spin pairs were then calculated. Comparison of the calculated and experimental RESPDOR curves indicates the particles are CsBr terminated (not PbBr2 terminated), with alkylammonium ligands situated within surface Cs vacancies, consistent with the surface-selective 133Cs NMR experiments. These results highlight the utility of high-resolution solid-state NMR spectroscopy for studying ligand binding and the surface structure of nanomaterials.

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“…While carboxylic acids, thiols, and phosphonic acids can be introduced as neutral molecules dissolved in organic solvent during ligand exchange, it is thought that these ligands bind as X-type ligands in their deprotonated form. 61 Different functional groups present different binding affinities for NC surfaces. Several studies 62−64 have measured the binding constants of ligands to CdSe NCs by NMR or NC PL quenching methods.…”

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Designing Transmitter Ligands That Mediate Energy Transfer between Semiconductor Nanocrystals and Molecules

2017

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Molecular control of energy transfer is an attractive proposition because it allows chemists to synthetically tweak various kinetic and thermodynamic factors. In this Perspective, we examine energy transfer between semiconductor nanocrystals (NCs) and π-conjugated molecules, focusing on the transmitter ligand at the organic−inorganic interface. Efficient transfer of triplet excitons across this interface allows photons to be directed for effective use of the entire solar spectrum. For example, a photon upconversion system composed of semiconductor NCs as sensitizers, bound organic ligands as transmitters, and molecular annihilators has the advantage of large, tunable absorption cross sections across the visible and near-infrared wavelengths. This may allow the near-infrared photons to be harnessed for photovoltaics and photocatalysis. Here we summarize the progress in this recently reported hybrid upconversion platform and point out the challenges. Since triplet energy transfer (TET) from NC donors to molecular transmitters is one of the bottlenecks, emphasis is on the design of transmitters in terms of molecular energetics, photophysics, binding affinity, stability, and energy offsets with respect to the NC donor. Increasing the efficiency of TET in this hybrid platform will increase both the up-and down-conversion quantum yields, potentially exceeding the Shockley−Queisser limit for photovoltaics and photocatalysis.

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Surface Chemistry of Colloidal Semiconductor Nanocrystals: Organic, Inorganic, and Hybrid

Cited by 8 publications

References 123 publications

Quantifying the Thermodynamics of Ligand Binding to CsPbBr₃ Quantum Dots

Quantifying the Thermodynamics of Ligand Binding to CsPbBr₃ Quantum Dots

Surface Termination of CsPbBr₃ Perovskite Quantum Dots Determined by Solid-State NMR Spectroscopy

Designing Transmitter Ligands That Mediate Energy Transfer between Semiconductor Nanocrystals and Molecules

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Surface Chemistry of Colloidal Semiconductor Nanocrystals: Organic, Inorganic, and Hybrid

Cited by 8 publications

References 123 publications

Quantifying the Thermodynamics of Ligand Binding to CsPbBr3 Quantum Dots

Quantifying the Thermodynamics of Ligand Binding to CsPbBr3 Quantum Dots

Surface Termination of CsPbBr3 Perovskite Quantum Dots Determined by Solid-State NMR Spectroscopy

Designing Transmitter Ligands That Mediate Energy Transfer between Semiconductor Nanocrystals and Molecules

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Product

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Quantifying the Thermodynamics of Ligand Binding to CsPbBr₃ Quantum Dots

Quantifying the Thermodynamics of Ligand Binding to CsPbBr₃ Quantum Dots

Surface Termination of CsPbBr₃ Perovskite Quantum Dots Determined by Solid-State NMR Spectroscopy