Dataset Information

Tailoring Cu+ for Ga3+ Cation Exchange in Cu2-xS and CuInS2 Nanocrystals by Controlling the Ga Precursor Chemistry.

ABSTRACT: Nanoscale cation exchange (CE) has resulted in colloidal nanomaterials that are unattainable by direct synthesis methods. Aliovalent CE is complex and synthetically challenging because the exchange of an unequal number of host and guest cations is required to maintain charge balance. An approach to control aliovalent CE reactions is the use of a single reactant to both supply the guest cation and extract the host cation. Here, we study the application of GaCl3-L complexes [L = trioctylphosphine (TOP), triphenylphosphite (TPP), diphenylphosphine (DPP)] as reactants in the exchange of Cu+ for Ga3+ in Cu2-xS nanocrystals. We find that noncomplexed GaCl3 etches the nanocrystals by S2- extraction, whereas GaCl3-TOP is unreactive. Successful exchange of Cu+ for Ga3+ is only possible when GaCl3 is complexed with either TPP or DPP. This is attributed to the pivotal role of the Cu2-xS-GaCl3-L activated complex that forms at the surface of the nanocrystal at the onset of the CE reaction, which must be such that simultaneous Ga3+ insertion and Cu+ extraction can occur. This requisite is only met if GaCl3 is bound to a phosphine ligand, with a moderate bond strength, to allow facile dissociation of the complex at the nanocrystal surface. The general validity of this mechanism is demonstrated by using GaCl3-DPP to convert CuInS2 into (Cu,Ga,In)S2 nanocrystals, which increases the photoluminescence quantum yield 10-fold, while blue-shifting the photoluminescence into the NIR biological window. This highlights the general applicability of the mechanistic insights provided by our work.

SUBMITTER: Hinterding SOM

PROVIDER: S-EPMC6890264 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Publications

Tailoring Cu+ for Ga3+ Cation Exchange in Cu2-xS and CuInS2 Nanocrystals by Controlling the Ga Precursor Chemistry.

Hinterding Stijn O M SOM Berends Anne C AC Kurttepeli Mert M Moret Marc-Etienne ME Meeldijk Johannes D JD Bals Sara S van der Stam Ward W de Mello Donega Celso C

ACS nano 20191022 11

Nanoscale cation exchange (CE) has resulted in colloidal nanomaterials that are unattainable by direct synthesis methods. Aliovalent CE is complex and synthetically challenging because the exchange of an unequal number of host and guest cations is required to maintain charge balance. An approach to control aliovalent CE reactions is the use of a single reactant to both supply the guest cation and extract the host cation. Here, we study the application of GaCl3-L complexes [L = triocty ...[more]

PMID: 31617701

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Project description:Oxide based dilute magnetic semiconductor materials have been of great interest over the years due to their potential use in spintronic devices. However, the variations in the magnetic behavior of the materials have raised concerns regarding the origin of ferromagnetic properties which still needs to be explored. Manipulation of magnetic behavior in oxide based dilute magnetic semiconductors has become a challenge due to the interplay of intrinsic defects present in the material. TiO2 nanocrystals have been studied largely due to their challenging optical and magnetic properties. The present investigation studies in detail the structural, morphological, optical and magnetic behavior of non-magnetic element (Cu and Zn) doped TiO2, synthesized via a simple sol-gel technique. X-ray diffraction patterns and Raman spectra confirm the anatase phase and high resolution transmission electron microscopic results clearly indicate the formation of highly crystalline nanocrystals in all the samples with particle size ranging from 5-15 nm. Energy dispersive X-ray fluorescence spectroscopic studies reveal the compositional homogeneity of all the investigated samples. The presence of functional groups and molecular interactions were identified by Fourier transform infrared spectroscopy. Optical properties were studied through UV-visible and photoluminescence spectroscopy from which a significant reduction in band gap in Cu-doped TiO2 nanocrystals was found. X-ray photoelectron spectra confirm the presence of Ti3+, Cu2+, Cu+ and Zn2+ in Cu and Zn-doped TiO2 samples. The concept of bound magnetic polarons associated with the vacancy defects at both Ti, Cu, Zn and oxygen sites is used to explain the induced weak ferromagnetic behavior in undoped, Cu and Zn-doped TiO2 at room temperature. The overlapping of bound magnetic polarons could be the source of ferromagnetism irrespective of the non-magnetic nature of the dopant ion. The concentration of bound magnetic polarons is estimated using a Langevin fit and a detailed understanding of the variation of defect mediated magnetic properties is established with the help of PL analysis. A significant reduction in bandgap along with enhanced magnetization observed in the Cu-doped TiO2 material makes it suitable as a potential candidate for spintronics and magneto-optics applications. Room temperature magnetic properties of the Zn doped sample show a diamagnetic tail which is explained based on the defect centers and oxidation states of dopant ions present in the sample which is further verified with the help of XPS results.

Dataset Information

Tailoring Cu+ for Ga3+ Cation Exchange in Cu2-xS and CuInS2 Nanocrystals by Controlling the Ga Precursor Chemistry.

Publications

Tailoring Cu<sup>+</sup> for Ga<sup>3+</sup> Cation Exchange in Cu<sub>2-<i>x</i></sub>S and CuInS<sub>2</sub> Nanocrystals by Controlling the Ga Precursor Chemistry.

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