Water-Soluble CdTe/CdS Core/Shell Semiconductor Nanocrystals: How Their Optical Properties Depend on the Synthesis Methods

Vale, Brener R. C.; Silva, Fernanda O.; Carvalho, Melissa S.; Raphael, Ellen; Ferrari, Jefferson L.; Schiavon, Marco A.

doi:10.3390/cryst6100133

Open AccessArticle

Water-Soluble CdTe/CdS Core/Shell Semiconductor Nanocrystals: How Their Optical Properties Depend on the Synthesis Methods

by

Brener R. C. Vale

,

Fernanda O. Silva

,

Melissa S. Carvalho

,

Ellen Raphael

,

Jefferson L. Ferrari

and

Marco A. Schiavon

^*

Grupo de Pesquisa em Química de Materiais—(GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP, São João del-Rei, Minas Gerais 36301-160, Brazil

^*

Author to whom correspondence should be addressed.

Crystals 2016, 6(10), 133; https://doi.org/10.3390/cryst6100133

Submission received: 31 July 2016 / Revised: 3 October 2016 / Accepted: 7 October 2016 / Published: 15 October 2016

(This article belongs to the Special Issue Colloidal Nanocrystals: Synthesis, Characterization and Application)

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Abstract

We conducted a comparative synthesis of water-soluble CdTe/CdS colloidal nanocrystalline semiconductors of the core/shell type. We prepared the CdS shell using two different methods: a one-pot approach and successive ionic layer adsorption and reaction (SILAR); in both cases, we used 3-mercaptopropionic acid (MPA) as the surface ligand. In the one-pot approach, thiourea was added over the freshly formed CdTe dispersion, and served as the sulfur source. We achieved thicker CdS layers by altering the Cd:S stoichiometric ratio (1:1, 1:2, 1:4, and 1:8). The Cd:S ratios 1:1 and 1:2 furnished the best optical properties; these ratios also made the formation of surface defects less likely. For CdTe/CdS obtained using SILAR, we coated the surface of three differently sized CdTe cores (2.17, 3.10, and 3.45 nm) with one to five CdS layers using successive injections of the Cd²⁺ and S^2– ions. The results showed that the core size influenced the optical properties of the materials. The deposition of three to five layers over the surface of smaller CdTe colloidal nanocrystals generated strain effects on the core/shell structure.

Keywords: core/shell; quantum dots; photoluminescence; strain effect; CdTe/CdS

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MDPI and ACS Style

Vale, B.R.C.; Silva, F.O.; Carvalho, M.S.; Raphael, E.; Ferrari, J.L.; Schiavon, M.A. Water-Soluble CdTe/CdS Core/Shell Semiconductor Nanocrystals: How Their Optical Properties Depend on the Synthesis Methods. Crystals 2016, 6, 133. https://doi.org/10.3390/cryst6100133

AMA Style

Vale BRC, Silva FO, Carvalho MS, Raphael E, Ferrari JL, Schiavon MA. Water-Soluble CdTe/CdS Core/Shell Semiconductor Nanocrystals: How Their Optical Properties Depend on the Synthesis Methods. Crystals. 2016; 6(10):133. https://doi.org/10.3390/cryst6100133

Chicago/Turabian Style

Vale, Brener R. C., Fernanda O. Silva, Melissa S. Carvalho, Ellen Raphael, Jefferson L. Ferrari, and Marco A. Schiavon. 2016. "Water-Soluble CdTe/CdS Core/Shell Semiconductor Nanocrystals: How Their Optical Properties Depend on the Synthesis Methods" Crystals 6, no. 10: 133. https://doi.org/10.3390/cryst6100133

APA Style

Vale, B. R. C., Silva, F. O., Carvalho, M. S., Raphael, E., Ferrari, J. L., & Schiavon, M. A. (2016). Water-Soluble CdTe/CdS Core/Shell Semiconductor Nanocrystals: How Their Optical Properties Depend on the Synthesis Methods. Crystals, 6(10), 133. https://doi.org/10.3390/cryst6100133

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

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Water-Soluble CdTe/CdS Core/Shell Semiconductor Nanocrystals: How Their Optical Properties Depend on the Synthesis Methods

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