Electron Injection from Colloidal PbS Quantum Dots into Titanium Dioxide Nanoparticles

ACS Nano ◽  
2008 ◽  
Vol 2 (11) ◽  
pp. 2206-2212 ◽  
Author(s):  
Byung-Ryool Hyun ◽  
Yu-Wu. Zhong ◽  
Adam C. Bartnik ◽  
Liangfeng Sun ◽  
Hector D. Abruña ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Titanium Dioxide ◽  
Titanium Dioxide Nanoparticles ◽  
Electron Injection ◽  
Pbs Quantum Dots

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 Semiconductor Quantum Dots (CdX, X = S, Te, Se) Modify Titanium Dioxide Nanoparticles for Photodynamic Inactivation of Leukemia HL60 Cancer Cells

2021 ◽  
Vol 2021 ◽  
pp. 1-24
Author(s):  
Qilin Pan ◽  
Miaomiao Li ◽  
Mucang Xiao ◽  
Yulu He ◽  
Guangyu Sun ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Titanium Dioxide ◽  
Visible Light ◽  
Separation Efficiency ◽  
Titanium Dioxide Nanoparticles ◽  
Semiconductor Quantum Dots ◽  
Photogenerated Carrier ◽  
Cdse Qds ◽  
Tio2 Nps ◽  
Targeting Ability

Titanium dioxide nanoparticles (TiO2-NPs) are highly efficient photosensitizers in traditional photodynamic therapy (PDT). The particle size of TiO2-NPs is small, only about 20 nm. However, the demands of ultraviolet light (UV) excitation feature shallow tissue penetration depth and may lead to severe tissue photon damage. Thus, in this research, TiO2-NPs are modified with semiconductor quantum dots (QDs) CdX (X = S, Te, Se) in various methods, such as ultrasonic, hydrothermal, sol-gel, aqueous phase, and hydrolysis precipitation. The transmission electron microscopy (TEM) images show that the size of CdSe-TiO2 is ranging from 6 to 14 nm. The ultraviolet-visible (UV-Vis) spectrum demonstrates that the CdX (X = S, Te, Se) modification can successfully extend the absorption range of TiO2-NPs into a different visible light region. CdSe QDs have the narrowest band gap compared with CdX (X = S, Te, Se) QDs. Visible light-activated CdSe-TiO2 nanocomposite shows the highest PDT inactivation efficiency toward HL60 cells compared with CdX-TiO2. The photogenerated carrier separation efficiency of CdSe-TiO2 nanocomposite is the highest shown in a fluorescence spectrum (FS). Furthermore, when conjugated with folic acid (FA), the prepared FA-CdX-TiO2 (X = S, Se) exhibits excellent cancer-targeting ability during PDT treatment. Optimum PDT efficiency of FA-CdSe-TiO2 indicates that photocatalytic and targeting ability is much higher than pure TiO2 and CdSe-TiO2. Our results provided a detailed investigation on the PDT performance of CdX (X = S, Te, Se) modified TiO2 and may act as a guide for further design of highly targeted performance visible-light response TiO2-NPs.

Synergistic Effect Between Halide Perovskites and PbS Quantum Dots

2020 ◽  
Author(s):  
Iván Mora-Seró ◽  
Sofia Masi ◽  
David Macias-Pinilla ◽  
Carlos Echeverría-Arrondo ◽  
Juan Ignacio Climente
Keyword(s):  
Quantum Dots ◽  
Synergistic Effect ◽  
Halide Perovskites ◽  
Pbs Quantum Dots
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