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Affiliation(s)
- Christopher Melnychuk
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
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Martin-Trasanco R, Esparza-Ponce HE, Ortiz PD, Oyarzun DP, Zuñiga C, Montero-Cabrera ME, Tundidor-Camba A, Pizarro GDC, Arratia-Pérez R. In-Situ Preparation of CdTe Quantum Dots Capped with a β-Cyclodextrin-Epichlorohydrin Polymer: Polymer Influence on the Nanocrystal's Optical Properties. NANOMATERIALS 2018; 8:nano8110948. [PMID: 30453604 PMCID: PMC6267504 DOI: 10.3390/nano8110948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 11/10/2018] [Accepted: 11/15/2018] [Indexed: 01/27/2023]
Abstract
β-Cyclodextrin (βCD), the less water soluble of the cyclodextrins, has been used as a capping agent in the preparation of semiconductor nanocrystals or quantum dots (QDs). Nevertheless, no reports have been found in the use of the highly water-soluble polymer of this, prepared by the crosslinking of the βCD units with epichlorohydrin in basic medium (βCDP). This polymer, besides to overcome the low solubility of the βCD, increases the inclusion constant of the guest; two parameters that deserve its use as capping agent, instead of the native cyclodextrin. In the present manuscript, we afforded the in-situ aqueous preparation of cadmium telluride (CdTe) QDs capped with βCDP. The polymer influence on the photoluminescent properties of the nanocrystals was analyzed. The βCDP controls the nanocrystals growth during the Oswald ripening stage. Consequently, the CdTe capped βCDP QDs showed lower Stokes-shift values, higher photoluminescent efficiency, and narrower size distribution than for nanocrystals obtained in the absence of polymer. Transmission electron microscopy (TEM) micrographs and energy dispersive X-ray spectroscopy (EDS) analysis revealed the composition and crystallinity of the CdTe QDs. This βCDP capped CdTe QDs is a potential scaffold for the supramolecular modification of QDs surface.
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Affiliation(s)
- Rudy Martin-Trasanco
- Center for Applyed Nanoscience (CANS), Doctorado de Físicoquímica Molecular Universidad Andres Bello, Av. República 275, Santiago 8370146, Chile.
| | - Hilda E Esparza-Ponce
- Centro de Investigación en Materiales Avanzados S.C, Ave. Miguel de Cervantes 120, Complejo Industrial Chihuahua, 31109 Chihuahua, Mexico.
| | - Pedro D Ortiz
- Departamento de Química Inorgánica, Facultad de Química, Pontificia Universidad Catolica de Chile, Avenida Vicuña Mackenna, 4860, Santiago 7820436, Chile.
| | - Diego P Oyarzun
- Center for Applyed Nanoscience (CANS), Doctorado de Físicoquímica Molecular Universidad Andres Bello, Av. República 275, Santiago 8370146, Chile.
| | - Cesar Zuñiga
- Center for Applyed Nanoscience (CANS), Doctorado de Físicoquímica Molecular Universidad Andres Bello, Av. República 275, Santiago 8370146, Chile.
| | - Maria E Montero-Cabrera
- Centro de Investigación en Materiales Avanzados S.C, Ave. Miguel de Cervantes 120, Complejo Industrial Chihuahua, 31109 Chihuahua, Mexico.
| | - Alain Tundidor-Camba
- Research Laboratory for Organic Polymers (RLOP), Faculty of Chemistry, Pontifícia Universidad Católica de Chile, Avenida Vicuña Mackenna, Santiago 7820436, Chile.
| | - Guadalupe Del C Pizarro
- Department of Chemistry, Technological Metropolitan University, J. P. Alessandri 1242., Santiago 7800003, Chile.
| | - Ramiro Arratia-Pérez
- Center for Applyed Nanoscience (CANS), Doctorado de Físicoquímica Molecular Universidad Andres Bello, Av. República 275, Santiago 8370146, Chile.
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Beane GA, Gong K, Kelley DF. Auger and Carrier Trapping Dynamics in Core/Shell Quantum Dots Having Sharp and Alloyed Interfaces. ACS NANO 2016; 10:3755-3765. [PMID: 26895220 DOI: 10.1021/acsnano.6b00370] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The role of interface sharpness in controlling the excited state dynamics in CdSe/ZnSe core/shell particles is examined here. Particles composed of CdSe/ZnSe with 2.4-4.0 nm diameter cores and approximately 4 monolayer shells are synthesized at relatively low temperature, ensuring a sharp core-shell interface. Subsequent annealing results in cadmium and zinc interdiffusion, softening the interface. TEM imaging and absorption spectra reveal that annealing results in no change in the particle sizes. Annealing results in a 5-10 nm blue shift in the absorption spectrum, which is compared to calculated spectral shifts to characterize the extent of metal interdiffusion. The one- and two-photon dynamics are measured using time-resolved absorption spectroscopy. We find that biexcitons undergo biexponential decays, with fast and slow decay times differing by about an order of magnitude. The relative magnitudes of the fast and slow components depend on the sharpness of the core-shell interface, with larger fast component amplitudes associated with a sharp core-shell interface. The slow component is assigned to Auger recombination of band edge carriers and the fast decay component to Auger recombination of holes that are trapped in defects produced by lattice strain. Annealing of these particles softens the core-shell interface and thereby reduces the amount of lattice strain and diminishes the magnitude of the fast decay component. The time constant of the slow biexciton Auger recombination component changes only slightly upon softening of the core-shell interface.
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Affiliation(s)
- Gary A Beane
- Chemistry and Chemical Biology, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - Ke Gong
- Chemistry and Chemical Biology, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - David F Kelley
- Chemistry and Chemical Biology, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
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