Thermochemical Measurements of Cation Exchange in CdSe Nanocrystals Using Isothermal Titration Calorimetry

Jharimune, Suprita; Sathe, Ajay A.; Rioux, Robert M.

doi:10.1021/acs.nanolett.8b02661

Cited by 33 publications

(50 citation statements)

References 79 publications

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“…From these measurements, the ligand-exchange thermodynamics can be understood. Reactions involving quantum dots were performed in isothermal titration calorimeters, such as ligand exchanges with different head groups, for example, metal halides 17 , alkylthiols 27 and alkylphosphonates 28,31 , as well as other reactions such as nanocrystal syntheses 78 , cation exchanges 85 and tail-group exchanges 31 . Although these measurements help with understanding the reactions on the surfaces of ligands, they also have the ability to probe the collective effects of ligands on nanocrystal surfaces 17,31 .…”

Section: Collective Effects Of the Organic Ligand Shellmentioning

confidence: 99%

The role of organic ligand shell structures in colloidal nanocrystal synthesis

2022

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olloidal nanocrystals bridge the gap between molecules and bulk materials, and enable researchers to probe fundamentals of nanomaterials, surfaces and size-dependent physics 1,2 . Beyond this, they have found a variety of applications from quantum dot emitters in displays 3,4 to photovoltaics 5,6 . Their colloidal nature allows them to be dispersed into solvents for optical studies, which include single-particle measurements 7,8 and assemblies of these materials can be created to investigate collective effects and their use as artificial atoms 9,10 .Fundamentally, most colloidal nanocrystals are composites that consist of an inorganic core and an organic ligand shell. This organic ligand shell enables colloidal stability in solvents 11,12 , prevents inorganic cores from fusing 10,13 , passivates undercoordinated atoms that lead to exciton traps in quantum dots [14][15][16][17] , acts as soft matter in the assembly of artificial solids 9,10,18,19 and provides a platform for the modification of inorganic cores 15,17,20 . Beyond contributing to colloidal nanocrystals properties, they are essential in synthesis.Organic ligands mediate growth by binding to growing nanocrystal surfaces as a surfactant. The group that binds to the nanocrystal surface is referred to as the head group, and the rest of the capping ligand is referred to as the tail group 1,19,21 . Typically, in hydrophobic environments, when growth is terminated by the exhaustion of precursors or reaction quenching, these ligands form an organic shell around each nanocrystal, in which the head groups face into the nanocrystal and the organic tail groups face outward. The nature of the ligands dictates the inorganic nanocrystal surface structure 11,19,21,22 , and has been designed to promote surfaces that minimize electronic trap states in quantum dots 15,17,23,24 . A variety of head groups are used to terminate colloidal nanocrystal surfaces, such as carboxylates, amines, phosphonates, thiols and halides, and often a mixture of capping groups is used [15][16][17]20,[25][26][27][28][29][30][31][32] . The amount, type and impurities of the ligands used in nanocrystal synthesis have implications for the nanocrystal size, shape, crystal structure and stability, as well as for their optical and electronic properties 33,34 .Head groups play a critical role in the control of colloidal nanocrystal growth, and different nanocrystal shapes can be formed by manipulating head group binding. Using combinations of

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Section: Collective Effects Of the Organic Ligand Shellmentioning

confidence: 99%

The role of organic ligand shell structures in colloidal nanocrystal synthesis

2022

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“…76 Rioux and colleagues reported the thermochemical measurements of cation exchange in CdSe NCs using isothermal titration calorimetry, including NC diameter, surface ligands, and reaction temperatures. 77 To date, research on the mechanisms of AERs and CERs is still necessary for fundamentals and applications.…”

Section: Effects Of Solvent and Ligandsmentioning

confidence: 99%

Cation/Anion Exchange Reactions toward the Syntheses of Upgraded Nanostructures: Principles and Applications

et al. 2020

Matter

105

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The last 5 years have witnessed rapid progress in the field of hybrid nanostructures toward enhanced optical and electronic properties. On this topic, we focus on the relevant progress that has been achieved on the basis of cation/anion exchange reactions (CERs/AERs). Different from those direct synthesis strategies, CERs/AERs can offer more freedom in tuning the chemical composition, crystal phases, doping, interfaces, and morphologies, which are key parameters to determine the optical and electronic properties of the target products. We present several examples, e.g., doped quantum dots (QDs), engineered core-shell QDs, metal-semiconductor hybrid nanostructures, hollow structures, and inorganic perovskite nanocrystals. These upgraded structures afforded by CERs/ AERs generally exhibit improved properties, such as increased quantum yields, prolonged lifetimes, and well-engineered band gaps for charge transportation and recombination, thus providing more opportunities for further advanced applications.

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“…In addition to the effect of ligand coverage on the reaction energy for surface growth and binding with ligands, and consequently the rate constants, the nanoparticle size could also have a strong effect on both. However, there are contradictory reports on the effect of size on ligand-nanoparticle binding energies [94][95][96] and surface reactivity. 97,98 Nevertheless, to PðtÞ ¼ sðtÞ D ave ðtÞ for two different cases; coverage-independent (green line) and coverage-dependent (blue dashed line) growth rate constant, and (c) comparison of the particle size distribution (frequency) for the two cases with the size distribution from TEM.…”

Section: Size-dependent Growth Rate Constantmentioning

confidence: 99%