Designed Synthesis of Solid and Hollow Cu_2–xTe Nanocrystals with Tunable Near-Infrared Localized Surface Plasmon Resonance

Abstract

Solid and hollow structures of Cu 2−x Te nanocrystals are synthesized by the injection of a Te−TOP solution at different reaction times. Both types of Cu 2−x Te nanocrystals exhibit an intense absorption peak (localized surface plasmon resonance (LSPR)) in the near-infrared region, arising from excess holes in the valence band, and high molar extinction coefficients of 2.6 × 10 7 M −1 cm −1 at 1150 nm and 8.1 × 10 7 M −1 cm −1 at 1200 nm are demonstrated for the solid-type and hollow-type Cu 2−x Te nanocrystals, respectively. The experimentally observed extinction spectra and calculated extinction spectra based on the electrostatic approximation are studied. The LSPR responses in the near-infrared (NIR) region for both solid and hollow Cu 2−x Te nanocrystals are affected by the refractive index of the medium, whereas the NIR resonance shift is more obvious in the hollow-type Cu 2−x Te nanocrystals. Furthermore, the localized surface plasmon band of the Cu 2−x Te nanostructures can be tuned by post processing via oxidation and reduction methods (controlling their degree of copper deficiency).

Plasmonic doped semiconductor nanocrystals: Properties, fabrication, applications and perspectives

“…Additionally, alloys of copper selenide with tin (copper-tinselenide, CTSe) [166,172] or alloys of copper sulfide with indium NCs (copper-indium-sulfide, CIS) [173] provide tunable LSPRs through the variation of the Cu:Sn [166] or Cu:In [173] ratio. Adapted with permission from ref [177] Copyright 2013 American Chemical Society.…”

“…The addition of the tellurium precursor then led to the formation of thin layers of Cu 2-x Te onto the Cu core surface, followed by the nanoscale Kirkendall process occurring at the interface between the Cu core and shell, leading to the observed hollow structure (Figure 21d). [177] While both, hollow and solid Cu 2-x Te NCs exhibit a single plasmon resonance, it was shown that hollow particles are more sensitive to the refractive index of the environment, which makes them interesting for sensing. [177] 5.…”

New materials for tunable plasmonic colloidal nanocrystals

“…22 Copper telluride NCs too have been investigated in detail. Yang et al 50 and Li et al 51 51 An interesting approach is to combine in one heterostructure a metallic and a doped semiconductor domain. Provided that both domains, when merged together, can retain their LSPRs, the heterostructure will exhibit high optical absorbance and near-field enhancement in a wider frequency range.…”

Plasmon-in-a-Box: On the Physical Nature of Few-Carrier Plasmon Resonances

“…Only more recently, plasmon resonances are being recognized to be ubiquitous, as exemplified by the induction of such resonances via free carrier doping in nanostructures of semiconductors and oxides. [9][10][11][12][13][14][15][16][17][18][19][20][21][22] Due to the long-held association of plasmons with electron dense metals, conventional wisdom has been that rather large numbers of carriers are required for a plasmon resonance. This notion had to be revised when the author's laboratory demonstrated in photodoped ZnO nanocrystals that a collection of as few as four electrons can display a plasmon resonance-like absorption, 19 as also shown subsequently by Gamelin and Massiello.…”