Colloidal Transition-Metal-Doped Quantum Dots

Beaulac, R√©mi; Ochsenbein, Stefan T.; Gamelin, Daniel R.

doi:10.1201/9781420079272-c11

Cited by 91 publications

(124 citation statements)

References 134 publications

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“…Ne 2 m*ε 0 ncτω 2 (1) where ε opt ) n 2 is a dielectric constant measured in the transparent region of the spectrum of an undoped semiconductor. The plasmon band maxima (solid blue squares) and positions (open red squares) in bcc-ITO NC absorption spectra normalized for the band-gap intensity are plotted as a function of Sn 4+ doping concentration in Figure 8b (inset).…”

Section: R Free Electrons )mentioning

confidence: 99%

Free Electron Concentration in Colloidal Indium Tin Oxide Nanocrystals Determined by Their Size and Structure

2010

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We report the synthesis and separation of colloidal indium tin oxide (ITO) nanocrystals in the stable cubic bixbyite (bcc-ITO) and metastable corundum (rh-ITO) phase under identical conditions, based on the size-structure correlation. Both phases are obtained in the same reactions, with nanocrystals below ca. 5 nm in size having corundum crystal structure. This bimodal size distribution allows for the separation of the nanocrystal phases by size selective precipitation. A comparative study of bcc-ITO and rh-ITO nanocrystals reveals a dramatic difference in their optical and electrical properties. Unlike smaller rh-ITO nanocrystals, bcc-ITO nanocrystals exhibit a strong absorption in the near-infrared (NIR) region arising from the plasmon oscillations due to the presence of free electrons. The difference in the free electron concentration in bcc-ITO and rh-ITO nanocrystals is related to the different electronic structure of the donor states, associated with Sn 4+ dopants, in these two nanocrystal allotropic modifications. The donor activation energy is significantly higher in rh-ITO NCs, prohibiting any appreciable concentration of free electrons in the conduction band. The increased replacement of organic protective ligands by anions in the solution leads to the oriented attachment of larger sized bcc-ITO nanocrystals and the formation of flowerlike clusters. These results demonstrate tuning of the optical and electrical properties of complex oxide nanocrystals by selecting their crystal and electronic structures through size and composition and allow for a designed preparation and controlled self-assembly of ITO nanocrystals.

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Section: R Free Electrons )mentioning

confidence: 99%

Free Electron Concentration in Colloidal Indium Tin Oxide Nanocrystals Determined by Their Size and Structure

2010

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“…The focus of this article is on the relationship of doping treatments to the effective medium electronic properties, specifically within the context of photovoltaic applications. The history of nanocrystal doping is rich, and we refer interested readers to comprehensive reviews on doping treatments for individual nanocrystals, including incorporating magnetic defects, 24,25 plasmonic defects, 26 and optically active isovalent impurities. 27,28 ■ FUNDAMENTALS OF DOPING: EQUILIBRIUM AND…”

Section: ■ Introductionmentioning

confidence: 99%

Postsynthetic Doping Control of Nanocrystal Thin Films: Balancing Space Charge to Improve Photovoltaic Efficiency

Engel

Alivisatos

2013

Chem. Mater.

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A semiconductor nanocrystal film is a unique class of nanocomposite, whose collective properties are determined by those of its constituents. Colloidal synthetic methods offer precise size control and finely tuned optical properties via quantum confinement, while recent improvements in charge transport through films have led to a variety of optoelectronic applications. However, understanding the role of defects and impurities in doping, crucial for optimizing device performance, has remained more elusive. In this perspective, we review recent progress in understanding and controlling the doping of semiconductor nanocrystal thin films, with a special focus on its relevance to photovoltaic applications. We highlight an array of postsynthetic techniques based on stoichiometric control, metal impurity incorporation, and electrochemical charging. We conclude with a review of the state of the art for nanocrystal photovoltaics, and propose the use of controlled doping and charge balance as a pathway to higher device efficiencies.

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“…[17][18][19][20] Within the past decade, attention has turned to magnetically doped semiconductor nanostructures like colloidal or self-assembled DMS quantum dots (QDs), 10,[21][22][23] motivated in part by potential quantum optics or information processing technologies. [24][25][26] DMSs quantum dots may enable versatile control of magnetism by means unavailable in their bulk counterparts, for example through lattice deformations (piezomagnetism), 27 exchange interactions involving closed-shell QD configurations, 28 and optical or electrical gating.…”

Section: Introductionmentioning

confidence: 99%

Orbital pathways for Mn2+-carriersp−dexchange in diluted magnetic semiconductor quantum dots

et al. 2011

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Abstract. Manganese-carrier magnetic exchange interactions in strongly quantum confined -conduction-band-electron interaction is described well using the recently proposed ferromagnetic kinetic s-s exchange pathway. Antiferromagnetic kinetic s-d exchange interactions previously proposed to become dominant in quantum confined diluted magnetic semiconductors (DMSs) have been evaluated quantitatively by both DFT and perturbation theory and are found to be weak compared to the ferromagnetic s-s interaction, even in these strongly confined QDs. The magnitudes of the mean-field exchange parameters are found to be nearly independent of quantum confinement over this range of QD diameters, and the dominant orbital pathways are not fundamentally altered by quantum confinement.i.

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Colloidal Transition-Metal-Doped Quantum Dots

Cited by 91 publications

References 134 publications

Free Electron Concentration in Colloidal Indium Tin Oxide Nanocrystals Determined by Their Size and Structure

Free Electron Concentration in Colloidal Indium Tin Oxide Nanocrystals Determined by Their Size and Structure

Postsynthetic Doping Control of Nanocrystal Thin Films: Balancing Space Charge to Improve Photovoltaic Efficiency

Orbital pathways for Mn2+-carriersp−dexchange in diluted magnetic semiconductor quantum dots

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