• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.139-140
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• 2005

The photocurrent characteristics of CdTe/HgTe/CdTe structured nanoparticles are studied. CdTe/HgTe/CdTe multilayer structured nanoparticles were synthesized by colloidal method. CdTe/HgTe/CdTe multilayer structured nanoparticles were characterized by x-ray diffraction, high-resolution transmission electron microscopy(HRTEM), absorbance and photoluminescence(PL). PL spectrum of CdTe/HgTe/CdTe multilayer structured nanoparticles exhibits a strong exciton bond in the near infrared range. The I-V curves and photoresponses revealed that CdTe/HgTe/CdTe multilayer structured nanoparticles are very prospective materials for the photodetectors.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2167-2170
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• 2013

A low-cost and simple recycling process of waste thermoelectric modules has been investigated using chemical reduction methods. The recycling is separated by two processes, such as dissolving and reduction. When the waste thermoelectric chips are immersed into a high concentration of $HNO_3$ aqueous solution at $100^{\circ}C$, oxide powders, e.g., $TeO_2$ and $Sb_2O_3$, are precipitated in the $Bi^{3+}$ and $HTeO{_2}^+$ ions contained solution. By employing a reduction process with the ions contained solutions, $Bi_2Te_3$ nanoparticles are successfully synthesized. Due to high reduction potential of $HTeO{_2}^+$ to Te, Te elements are initially formed and subsequently $Bi_2Te_3$ nanoparticles are formed. The average particle size of $Bi_2Te_3$ was calculated to be 25 nm with homogeneous size distribution. On the other hand, when the precipitated powders reduced by hydrazine, $Sb_2O_3$ and Te nanoparticles are synthesized because of higher reduction potentials of $TeO_2$ to Te. After the washing step, the $Sb_2O_3$ are clearly removed, results in Te nanoparticles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.37-40
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• 2004

CdTe nanoparticles were synthesized in aqueous solution by colloidal method. The absorption and photoluminescence(PL) spectrum of the synthesized CdTe nanoparticles revealed the strong exitonic peak in the visible region. Photocurrent of CdTe nanoparticles were observed in the structure of Al/CdTe/ITO that was fabricated by spin coating of CdTe nanoparticles. The wavelength dependence of photocurrent was very similar to the absorption spectrum, indicating the charges generated by the absorption of photons give direct contribution to photocurrent. This study suggests that CdTe nanoparticles are very prospective materials for optoelectronics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.60-62
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• 2004

CdTe nanoparticles were synthesized in aqueous solution by colloidal method. The absorption and photoluminescence(PL) spectrum of the synthesized CdTe nanoparticles revealed the strong exitonic peak in the visible region. Electroluminescence of CdTe nanoparticles were observed in the structure of Al/CdTe/PVK/ITO and Al/CdTe/PEDOT/ITO that were fabricated by spin coating of polyvinylcarvazole(PVK), poly(3,4-ethylenedioxythiophene(PEDOT) and CdTe nanoparticles. The turn-on voltages of Al/CdTe/PVK/ITO and Al/CdTe/PEDOT/ITO for electroluminescence were 5V and 6V, respectively. We identified that the reduction of turn-on voltage resulted from the increase of hole injection into the hole transport layer due to lower ionization energy of PEDOT.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1123-1127
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• 2010

We report a simple and quick route for the preparation of high-quality, nearly monodisperse $Bi_2Te_3$, $Sb_2Te_3$, and $Bi_xSb_{2-x}-Te_3$ nanocrystallites. The reactions of bismuth acetate or antimony acetate with Te in oleic acid result in pure phase of $Bi_2Te_3$ or $Sb_2Te_3$ nanoparticles, respectively. Also, ternary $Bi_xSb_{2-x}Te_3$ nanoparticles were successfully synthesized using the same method. The size and morphology of the nanoparticles were controlled by varying the stabilizing agents. The as-prepared nanoparticles are characterized by X-ray diffraction, scanning electron microscope, and high-resolution transmission electron microscope using an energy dispersive spectroscopy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.25-28
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• 2004

Photocurrent spectrum, photoresponse, and I-V measurements were made for close-packed HgTe nanoparticles without organic capping materials to investigate their photocurrent characteristics in the infrared range. In absorption and photoluminescence (PL) spectra taken for the close-packed nanoparticles film, the wavelengths of exciton peaks was red-shifted, compared with organic capped HgTe nanoparticles dispersed in solution. This red-shift is caused by the lessening of the exciton binding energy. The I-V curves and photoresponse for the close-packed nanoparticles film reveal their dark current and fast photoresponse with no current decay, respectively. The observation suggests that the HgTe nanoparticles are a very prospect material applicable for photodetectors in the whole IR range.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1082-1085
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• 2012

CdTe nanoribbons feature their unique optical properties compared with CdTe nanoparticles. Slow oxidation of tellurium ions on CdTe nanoparticles resulted in the organization of individual nanoparticle into nanoribbons. The light-controlled self-assembly of CdTe nanoparticles led to twisted ribbons. It was found that irradiation improved the oxidation of tellurium ions. Transmission electron microscopy (TEM) were performed to characterize the synthesized nanostructures and showed nanowires were twisted after self-assembly. The photoluminescence was slightly blue-shifted from 550 to 544 nm. This synthetic procedure could potentially provide a key step toward the fabrication of nanowires.

• Journal of Institute of Convergence Technology
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• v.3 no.1
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• pp.51-54
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• 2013

Cadmium telluride(CdTe) nanowires were successfully synthesized from individual nanoparticles via self-assembly and the evolutionary process was investigated. The oxidation of tellurium ions on CdTe nanoparticles resulted in the organization of individual nanoparticle into twisted-nanoribbons. The nanoparticles self-assembled to twisted ribbons under light while nanoparticles under dark transformed to straight nanowires made of several layers of individual nanoparticles. The images of nanoribbons were analysed based on transmission electron microscopy and scanning electron microscopy. The photoluminescence was blue-shifted from 555 to 545nm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.4
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• pp.315-320
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• 2013

The composites composed of conducting polymer (MEH-PPV), CdTe nanoparticles, and multiwalled carbon nanotubes (MWNTs) were spectroscopically and electrically characterized in their thin films. The composite films were prepared by spray coating. These composites were prepared from the mixture solution of MEH-PPV and CdTe-embedded MWNTs, in which CdTe nanoparticles were electrostatically bound to MWNTs. UV/vis and PL spectra were analyzed to investigate the optical absorbance and emission of the composite films. In addition, their structural, electrochemical, and electrical properties were studied by transmission electron microscopy, cyclic voltammetry, and I-V measurement.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2207-2211
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• 2011

Colloidal cadmium telluride (CdTe) quantum dots (QDs) and their nanoparticles have been synthesized by one pot sonochemical reactions under multibubble sonoluminescence (MBSL) conditions, which are quite mild and facile compared to other typical high temperature solution-based methods. For a typical reaction, $CdCl_2$ and tellurium powder with hexadecylamine and trioctylphosphine/trioctylphosphineoxide (TOP/TOPO) as a dispersant were sonicated in toluene solvent at 20 KHz and a power of 220W for 5-40 min at 60 $^{\circ}C$. The sizes of CdTe particles, in a very wide size range from 2 nm-30 ${\mu}m$, were controllable by varying the sonicating and thermal heating conditions. The prepared CdTe QDs show different colors from pale yellow to dark brown and corresponding photoluminescence properties due mainly to the quantum confinement effect. The CdTe nanoparticles of about 20 nm in average were found to have band gap of 1.53 eV, which is the most optimally matched band gap to solar spectrum.