A size dependent discontinuous decay rate for the exciton emission in ZnO quantum dots

2014 ◽  
Vol 16 (27) ◽  
pp. 13849-13857 ◽  
Author(s):  
T. Jesper Jacobsson ◽  
Sviatlana Viarbitskaya ◽  
Emad Mukhtar ◽  
Tomas Edvinsson
Keyword(s):  
Quantum Dots ◽  
Decay Rate ◽  
Laser Spectroscopy ◽  
Time Resolved ◽  
Exciton Emission ◽  
Uv Fluorescence ◽  
Size Dependent ◽  
Zno Quantum Dots

Possible transitions related to the UV-fluorescence in ZnO quantum dots, here investigated by time resolved laser spectroscopy.

In Situ and Simultaneous UV−vis/SAXS and UV−vis/XAFS Time-Resolved Monitoring of ZnO Quantum Dots Formation and Growth

2011 ◽  
Vol 115 (11) ◽  
pp. 4404-4412 ◽  
Author(s):  
Bruno L. Caetano ◽  
Celso V. Santilli ◽  
Florian Meneau ◽  
Valérie Briois ◽  
Sandra H. Pulcinelli
Keyword(s):  
Quantum Dots ◽  
Time Resolved ◽  
Zno Quantum Dots

Temperature and size dependence of time-resolved exciton recombination in ZnO quantum dots

2011 ◽  
Vol 99 (24) ◽  
pp. 243107 ◽  
Author(s):  
I. Musa ◽  
F. Massuyeau ◽  
L. Cario ◽  
J. L. Duvail ◽  
S. Jobic ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Size Dependence ◽  
Time Resolved ◽  
Exciton Recombination ◽  
Zno Quantum Dots

Origin of Visible Photoluminescence of ZnO Quantum Dots: Defect-Dependent and Size-Dependent

2010 ◽  
Vol 114 (21) ◽  
pp. 9651-9658 ◽  
Author(s):  
Luyuan Zhang ◽  
Longwei Yin ◽  
Chengxiang Wang ◽  
Ning lun ◽  
Yongxin Qi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Size Dependent ◽  
Visible Photoluminescence ◽  
Zno Quantum Dots

scholarly journals Effect of energy transfer on the optical properties of surface-passivated perovskite films with CdSe/ZnS quantum dots

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Il-Wook Cho ◽  
Mee-Yi Ryu
Keyword(s):  
Quantum Dots ◽  
Energy Transfer ◽  
Transfer Rate ◽  
Surface Passivation ◽  
Hybrid Structure ◽  
Core Diameter ◽  
Time Resolved ◽  
Size Dependent ◽  
The Core ◽  
Charge Transfer Rate

AbstractSurface passivation is an effective method to protect the surfaces and improve the luminescence properties of perovskite (PS) films. CdSe/ZnS core-shell quantum dots (QDs) have been employed for surface passivation of PS films because of their size-dependent tunable bandgaps. Herein, the energy transfer (ET) behavior of CH3NH3PbI2Br PS films covered with CdSe/ZnS QDs (QD/PS hybrid structures) is characterized by using photoluminescence (PL) and time-resolved PL spectroscopy. The PL decay time and the integrated PL intensity of the QD/PS hybrid structure increase compared with those of the bare PS films, owing to ET from the QDs to the PS and reduced charge traps. The ET efficiency increases from ~7% to 63% for the QD/PS hybrid structure when the core diameter of the QDs decreases from 6.5 to 2.7 nm, respectively. This can be explained by the charge transfer rate enhancement due to the control of energy level alignment of QDs. These results allow us to understand fundamental mechanisms such as ET from QDs to PS films as a function of the size of the QD.

scholarly journals Electrical control of single-photon emission in highly charged individual colloidal quantum dots

2020 ◽  
Vol 6 (38) ◽  
pp. eabb1821
Author(s):  
Sergii Morozov ◽  
Evangelina L. Pensa ◽  
Ali Hossain Khan ◽  
Anatolii Polovitsyn ◽  
Emiliano Cortés ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Decay Rate ◽  
Room Temperature ◽  
Single Photon ◽  
Photon Emission ◽  
Fold Increase ◽  
Single Photon Emission ◽  
Time Resolved ◽  
Efficient Lasing

Electron transfer to an individual quantum dot promotes the formation of charged excitons with enhanced recombination pathways and reduced lifetimes. Excitons with only one or two extra charges have been observed and exploited for very efficient lasing or single–quantum dot light-emitting diodes. Here, by room-temperature time-resolved experiments on individual giant-shell CdSe/CdS quantum dots, we show the electrochemical formation of highly charged excitons containing more than 12 electrons and 1 hole. We report the control over intensity blinking, along with a deterministic manipulation of quantum dot photodynamics, with an observed 210-fold increase in the decay rate, accompanied by 12-fold decrease in the emission intensity, while preserving single-photon emission characteristics. These results pave the way for deterministic control over the charge state, and room-temperature decay rate engineering for colloidal quantum dot–based classical and quantum communication technologies.

Size-Dependent Photothermal Performance of Silicon Quantum Dots

2021 ◽  
Vol 125 (6) ◽  
pp. 3421-3431
Author(s):  
İrem Nur Gamze Özbilgin ◽  
Batu Ghosh ◽  
Hiroyuki Yamada ◽  
Naoto Shirahata
Keyword(s):  
Quantum Dots ◽  
Silicon Quantum Dots ◽  
Size Dependent

scholarly journals A method for studying pico to microsecond time-resolved core-level spectroscopy used to investigate electron dynamics in quantum dots

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tamara Sloboda ◽  
Sebastian Svanström ◽  
Fredrik O. L. Johansson ◽  
Aneta Andruszkiewicz ◽  
Xiaoliang Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Electron Injection ◽  
Core Level ◽  
Pump Laser ◽  
Repetition Frequency ◽  
Specific Information ◽  
Single Experiment ◽  
Time Resolved ◽  
X Ray ◽  
Pbs Quantum Dots

AbstractTime-resolved photoelectron spectroscopy can give insights into carrier dynamics and offers the possibility of element and site-specific information through the measurements of core levels. In this paper, we demonstrate that this method can access electrons dynamics in PbS quantum dots over a wide time window spanning from pico- to microseconds in a single experiment carried out at the synchrotron facility BESSY II. The method is sensitive to small changes in core level positions. Fast measurements at low pump fluences are enabled by the use of a pump laser at a lower repetition frequency than the repetition frequency of the X-ray pulses used to probe the core level electrons: Through the use of a time-resolved spectrometer, time-dependent analysis of data from all synchrotron pulses is possible. Furthermore, by picosecond control of the pump laser arrival at the sample relative to the X-ray pulses, a time-resolution limited only by the length of the X-ray pulses is achieved. Using this method, we studied the charge dynamics in thin film samples of PbS quantum dots on n-type MgZnO substrates through time-resolved measurements of the Pb 5d core level. We found a time-resolved core level shift, which we could assign to electron injection and charge accumulation at the MgZnO/PbS quantum dots interface. This assignment was confirmed through the measurement of PbS films with different thicknesses. Our results therefore give insight into the magnitude of the photovoltage generated specifically at the MgZnO/PbS interface and into the timescale of charge transport and electron injection, as well as into the timescale of charge recombination at this interface. It is a unique feature of our method that the timescale of both these processes can be accessed in a single experiment and investigated for a specific interface.

scholarly journals Synthesis and Characterization of Polyvinylpyrrolidone-Modified ZnO Quantum Dots and Their In Vitro Photodynamic Tumor Suppressive Action

2021 ◽  
Vol 22 (15) ◽  
pp. 8106
Author(s):  
Tianming Song ◽  
Yawei Qu ◽  
Zhe Ren ◽  
Shuang Yu ◽  
Mingjian Sun ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Photodynamic Therapy ◽  
Inhibitory Effect ◽  
Therapeutic Effects ◽  
In Vivo Experiments ◽  
Potential Applications ◽  
Zno Quantum Dots ◽  
Zno Qds

Despite the numerous available treatments for cancer, many patients succumb to side effects and reoccurrence. Zinc oxide (ZnO) quantum dots (QDs) are inexpensive inorganic nanomaterials with potential applications in photodynamic therapy. To verify the photoluminescence of ZnO QDs and determine their inhibitory effect on tumors, we synthesized and characterized ZnO QDs modified with polyvinylpyrrolidone. The photoluminescent properties and reactive oxygen species levels of these ZnO/PVP QDs were also measured. Finally, in vitro and in vivo experiments were performed to test their photodynamic therapeutic effects in SW480 cancer cells and female nude mice. Our results indicate that the ZnO QDs had good photoluminescence and exerted an obvious inhibitory effect on SW480 tumor cells. These findings illustrate the potential applications of ZnO QDs in the fields of photoluminescence and photodynamic therapy.

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