Effect of Surface Trap States on Photocatalytic Activity of Semiconductor Quantum Dots

2018 ◽  
Vol 122 (17) ◽  
pp. 9312-9319 ◽  
Author(s):  
Haoyang Zou ◽  
Chunwei Dong ◽  
Suyu Li ◽  
Chan Im ◽  
Mingxing Jin ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Photocatalytic Activity ◽  
Semiconductor Quantum Dots ◽  
Trap States ◽  
Surface Trap ◽  
Effect Of Surface

scholarly journals Size-Dependent Non-FRET Photoluminescence Quenching in Nanocomposites Based on Semiconductor Quantum Dots CdSe/ZnS and Functionalized Porphyrin Ligands

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Eduard I. Zenkevich ◽  
Thomas Blaudeck ◽  
Alexander Milekhin ◽  
Christian von Borczyskowski
Keyword(s):  
Quantum Dots ◽  
Charge Transfer ◽  
Semiconductor Quantum Dots ◽  
Trap States ◽  
Quenching Rate ◽  
Time Resolved ◽  
Exciton Wave Function ◽  
Electron Hole Pair ◽  
Colloidal Semiconductor ◽  
Pl Quenching

We review recent experimental work to utilize the size dependence of the luminescence quenching of colloidal semiconductor quantum dots induced by functionalized porphyrin molecules attached to the surface to describe a photoluminescence (PL) quenching process which is different from usual models of charge transfer (CT) or Foerster resonant energy transfer (FRET). Steady-state and picosecond time-resolved measurements were carried out for nanocomposites based on colloidal CdSe/ZnS and CdSe quantum dots (QDs) of various sizes and surfacely attached tetra-mesopyridyl-substituted porphyrin molecules (“Quantum Dot-Porphyrin” nanocomposites), in toluene at 295 K. It was found that the major part of the observed strong quenching of QD PL in “QD-Porphyrin” nanocomposites can neither be assigned to FRET nor to photoinduced charge transfer between the QD and the chromophore. This PL quenching depends on QD size and shell and is stronger for smaller quantum dots: QD PL quenching rate constants scale inversely with the QD diameter. Based on the comparison of experimental data and quantum mechanical calculations, it has been concluded that QD PL quenching in “QD-Porphyrin” nanocomposites can be understood in terms of a tunneling of the electron (of the excited electron-hole pair) followed by a (self-) localization of the electron or formation of trap states. The major contribution to PL quenching is found to be proportional to the calculated quantum-confined exciton wave function at the QD surface. Our findings highlight that single functionalized molecules can be considered as one of the probes for the complex interface physics and dynamics of colloidal semiconductor QD.

Band Edge Recombination in CdSe, CdS and CdSxSe1−xAlloy Nanocrystals Observed by Ultrafast Fluorescence Upconversion: The Effect of Surface Trap States

2008 ◽  
Vol 112 (33) ◽  
pp. 12736-12746 ◽  
Author(s):  
Maria Danielle Garrett ◽  
Albert D. Dukes III ◽  
James R. McBride ◽  
Nathanael J. Smith ◽  
Stephen J. Pennycook ◽  
...  
Keyword(s):  
Band Edge ◽  
Trap States ◽  
Surface Trap ◽  
Fluorescence Upconversion ◽  
Effect Of Surface

The Enhancement of Band Edge Emission from ZnS/Zn(OH)2 Quantum Dots

2000 ◽  
Vol 642 ◽  
Author(s):  
Hatim Mohamed El-Khair ◽  
Ling Xu ◽  
Xinfan Huang ◽  
Minghai Li ◽  
Xiaofeng Gu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Surface Passivation ◽  
Band Edge ◽  
Band Edge Emission ◽  
Trap States ◽  
Edge Emission ◽  
Surface Trap ◽  
Quantum Size ◽  
Transmission Electron

ABSTRACTWurtzite structure monodisperse ZnS quantum dots (QDs) of 1 to 5 nm diameter, synthesized by colloidal chemical method, were confirmed by transmission electron microscopy (TEM) images and electron diffraction (ED) patterns. Enhanced blue shifted band edge emission from Zn(OH)2 capped ZnS QDs with decreasing size has been observed, which indicates the role of inorganic surface passivation and hence supports the quantum size effect. Detectable far-red shifted emission from bare ZnS QDs has been observed when QDs precursors and stabilizer dispersed in solvents with different polarities. This emission is attributed to the surface trap states of different energies.

Origin of surface trap states in CdS quantum dots: relationship between size dependent photoluminescence and sulfur vacancy trap states

2015 ◽  
Vol 17 (4) ◽  
pp. 2850-2858 ◽  
Author(s):  
Aisea Veamatahau ◽  
Bo Jiang ◽  
Tom Seifert ◽  
Satoshi Makuta ◽  
Kay Latham ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Trap States ◽  
Cds Quantum Dots ◽  
Trap State ◽  
Sulfur Vacancy ◽  
Surface Trap ◽  
Trapped Electrons ◽  
Size Dependent ◽  
Cds Quantum Dot

Trap state emission mainly originates from deep trapped electrons at surface Cd with sulfur vacancy sites of CdS quantum dot.

The effect of annealing and photoactivation on the optical transitions of band–band and surface trap states of colloidal quantum dots in PMMA

2011 ◽  
Vol 22 (12) ◽  
pp. 125202 ◽  
Author(s):  
Lian Hu ◽  
Huizhen Wu ◽  
Lingxiao Du ◽  
Hongying Ge ◽  
Xin Chen ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Colloidal Quantum Dots ◽  
Optical Transitions ◽  
Trap States ◽  
Surface Trap

Semiconductor Quantum Dots for Multicolor Fluorescence Imaging and Spectroscopy of Single Cancer Cells

2003 ◽  
Vol 773 ◽  
Author(s):  
Xiaohu Gao ◽  
Shuming Nie ◽  
Wallace H. Coulter
Keyword(s):  
Quantum Dots ◽  
Cancer Cells ◽  
Fluorescence Imaging ◽  
Organic Dyes ◽  
Fluorescent Proteins ◽  
Single Cells ◽  
Quantitative Imaging ◽  
Semiconductor Quantum Dots ◽  
Single Cancer ◽  
Imaging And Spectroscopy

AbstractLuminescent quantum dots (QDs) are emerging as a new class of biological labels with unique properties and applications that are not available from traditional organic dyes and fluorescent proteins. Here we report new developments in using semiconductor quantum dots for quantitative imaging and spectroscopy of single cancer cells. We show that both live and fixed cells can be labeled with multicolor QDs, and that single cells can be analyzed by fluorescence imaging and wavelength-resolved spectroscopy. These results raise new possibilities in cancer imaging, molecular profiling, and disease staging.

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