scholarly journals Hole-Induced Electron Transport through Core−Shell Quantum Dots: A Direct Measurement of the Electron−Hole Interaction

Nano Letters ◽  
2010 ◽  
Vol 10 (5) ◽  
pp. 1931-1935 ◽  
Author(s):  
Ingmar Swart ◽  
Zhixiang Sun ◽  
Daniël Vanmaekelbergh ◽  
Peter Liljeroth
Keyword(s):  
Quantum Dots ◽  
Electron Transport ◽  
Direct Measurement ◽  
Core Shell ◽  
Electron Hole ◽  
Hole Interaction

Interband Optical Transition Energies in Type-II PbSe/PbS Core/Shell Quantum Dots

2017 ◽  
Vol 6 (1) ◽  
pp. 80-86
Author(s):  
S. N. Saravanamoorthy ◽  
A. John Peter
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Shell Thickness ◽  
Optical Transition ◽  
Hole Pair ◽  
Core Shell ◽  
Type Ii ◽  
Electron Hole ◽  
Transition Energies ◽  
Electron Hole Pair

Electronic and optical properties of Type-II lead based core/shell semiconducting quantum dots are reported. Binding energies of electron–hole pair, optical transition energies and the absorption coefficients are investigated taking into account the geometrical confinement in PbSe/PbS core/shell quantum dot nanostructure. The energies are obtained with the increase of shell thickness for various inner core radii. The probability densities of electron and hole wave functions of radial coordinate of the core PbSe and PbS shell quantum dots are presented. The optical transition energy with the spatial confinement is brought out. The electronic properties are obtained using variational approach whereas the compact density matrix method is employed for the nonlinear optical properties. The results show that (i) a decrease in binding energy is obtained when the shell thickness increases due to more separation of electron–hole pair and (ii) the energy band gap decreases with the increase in the shell thickness resulting in the reduction of the higher energy interband transitions.

scholarly journals Long Electron−Hole Separation of ZnO-CdS Core−Shell Quantum Dots

2009 ◽  
Vol 113 (45) ◽  
pp. 19419-19423 ◽  
Author(s):  
Fen Xu ◽  
Vyacheslav Volkov ◽  
Yimei Zhu ◽  
Hanying Bai ◽  
Anthony Rea ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Core Shell ◽  
Electron Hole

Quantum Dot Array LED Research with ZnO as an Electron Transport Layer

2013 ◽  
Vol 333-335 ◽  
pp. 1895-1898
Author(s):  
Jia Zhao ◽  
Xiao Yu Zhang ◽  
Yu Zhang ◽  
Yi Feng ◽  
Tie Qiang Zhang ◽  
...  
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Core Shell ◽  
Cdse Core ◽  
Electron Hole ◽  
Light Emitting ◽  
Light Stability ◽  
Hole Recombination

As a new light-emitting material, quantum dot having the advantages of other materials that can not be replaced. It is not only the fluorescence quantum yield, and light stability. Therefore, we use CdSe core-shell structure of the quantum dot LED devices as the electron-hole recombination layer. In this paper, we synthesized emission peak is located at 588nm CdSe core-shell quantum dots, and made array display LED devices with ZnO as the electron transport layer.

Preparation and Characterization of Water-Soluble CdSe/CdS Core/Shell Quantum Dots

2012 ◽  
Vol 549 ◽  
pp. 212-215
Author(s):  
Ming Li Li ◽  
Qiong Yu ◽  
Ying Xu ◽  
Chun Jiang Zhou ◽  
Qing Guo Lu
Keyword(s):  
Quantum Dots ◽  
Energy Band ◽  
Xrd Analysis ◽  
High Energy ◽  
Water Soluble ◽  
Excitation Wavelength ◽  
Core Shell ◽  
Electron Hole ◽  
Energy Peak

Cadmium Selenide/Cadmium Sulfide (CdSe/CdS) core/shell quantum dots (QDs) in aqueous solution were prepared by solve-separate method using CdSe as core and mercapto-acetate acid as stabilizer and surfactants. The results of experiments indicate that the size of the CdSe/CdS QDs was about 5nm estimated by FE-TEM, which is accordant with that calculated from the XRD data by the Scherer equation after emendation. The QDs belong to the cubic structure (zinc blende) by XRD analysis. The intensity of luminescence of the quantum dots was greatly improved after the surface was coated with CdS shell. With increasing the time of refluence, the intensity of photoluminescence was promoted correspondingly. The excitation wavelength was 350nm, two emission peaks were clearly observed, the first high-energy peak was at 600nm and the second one located in 700nm. The first high-energy band was attributed to electron–hole recombination after relaxation and the second energy band was to deep traps in quantum-confined systems.

scholarly journals High-Performance Core/Shell of ZnO/TiO2 Nanowire with AgCl-Doped CdSe Quantum Dots Arrays as Electron Transport Layer for Perovskite Solar Cells

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3969
Author(s):  
Jin Mo Kim ◽  
Bong Soo Lee ◽  
Sung Won Hwang
Keyword(s):  
Quantum Dots ◽  
Solar Cells ◽  
Electron Transport ◽  
Conversion Efficiency ◽  
Perovskite Solar Cells ◽  
Transport Layer ◽  
Atmospheric Environment ◽  
Electron Transport Layer ◽  
Core Shell ◽  
Cdse Quantum Dots

Most previous studies of perovskite core/shell structures have been based on ZnO/TiO2 nanowires (NWs), which are not suitable for high photoelectric conversion efficiency. Here, core/shell ZnO/TiO2 NWs with AgCl-doped CdSe quantum dots were fabricated as an electron transport layer (ETL) for perovskite solar cells, based on ZnO/TiO2 arrays. We designed CdSe with AgCl dopants that were synthesized by a colloidal process. An improvement of the recombination barrier (Rct1), due to shell supplementation with AgCl-doped CdSe quantum dots, improved the open circuit voltage, the fill factor, and the adsorption capacity of CH3NH3PbI3 perovskite with NWs. The enhanced cell steady state was attributable to TiO2 with AgCl-doped CdSe QD supplementation. A maximum power conversion efficiency of 15.12% was attained in an atmospheric environment. The mechanism of the recombination and electron transport in the perovskite solar cells becoming the basis of ZnO/TiO2 core/shell arrays was investigated to represent the merit of ZnO/TiO2 core/shell arrays as an electron transport layer in effective devices. These results showed an uncomplicated approach for restraining non-radiative recombination loss in hetero-structure core/shell arrays to significantly improve perovskite solar cell performance and increase the effectiveness of photovoltaics.

scholarly journals Transport studies of electron-hole and spin-orbit interaction in GaSb/InAsSb core-shell nanowire quantum dots

2015 ◽  
Vol 91 (16) ◽  
Author(s):  
Bahram Ganjipour ◽  
Martin Leijnse ◽  
Lars Samuelson ◽  
H. Q. Xu ◽  
Claes Thelander
Keyword(s):  
Quantum Dots ◽  
Orbit Interaction ◽  
Core Shell ◽  
Spin Orbit ◽  
Electron Hole ◽  
Spin Orbit Interaction ◽  
Transport Studies

Nanostructure of semiconductor quantum dots in a borosilicate glass matrix by complementary use of HREM and AEM

1990 ◽  
Vol 48 (4) ◽  
pp. 728-729
Author(s):  
M.J. Kim ◽  
L.C. Liu ◽  
S.H. Risbud ◽  
R.W. Carpenter
Keyword(s):  
Quantum Dots ◽  
Borosilicate Glass ◽  
Glass Matrix ◽  
Optical Switching ◽  
Response Times ◽  
Fast Response ◽  
Processing Technique ◽  
Internal Stresses ◽  
Electron Hole ◽  
Spatial Dimensions

When the size of a semiconductor is reduced by an appropriate materials processing technique to a dimension less than about twice the radius of an exciton in the bulk crystal, the band like structure of the semiconductor gives way to discrete molecular orbital electronic states. Clusters of semiconductors in a size regime lower than 2R {where R is the exciton Bohr radius; e.g. 3 nm for CdS and 7.3 nm for CdTe) are called Quantum Dots (QD) because they confine optically excited electron- hole pairs (excitons) in all three spatial dimensions. Structures based on QD are of great interest because of fast response times and non-linearity in optical switching applications.In this paper we report the first HREM analysis of the size and structure of CdTe and CdS QD formed by precipitation from a modified borosilicate glass matrix. The glass melts were quenched by pouring on brass plates, and then annealed to relieve internal stresses. QD precipitate particles were formed during subsequent "striking" heat treatments above the glass crystallization temperature, which was determined by differential thermal analysis.

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