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A method for studying pico to microsecond time resolved core level spectroscopy used to investigate electron dynamics in quantum dots
- Source :
- Scientific Reports, Scientific Reports, Vol 10, Iss 1, Pp 1-14 (2020)
- Publication Year :
- 2020
-
Abstract
- Time-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.
- Subjects :
- Materials science
Atom and Molecular Physics and Optics
Science
02 engineering and technology
Laser pumping
Electron
010402 general chemistry
Physical Chemistry
01 natural sciences
Article
law.invention
Surfaces, interfaces and thin films
law
Thin film
Spectroscopy
Fysikalisk kemi
Multidisciplinary
Quantum dots
business.industry
Accelerator research and development
021001 nanoscience & nanotechnology
Synchrotron
0104 chemical sciences
Microsecond
Physical chemistry
Quantum dot
Picosecond
Medicine
Optoelectronics
Atom- och molekylfysik och optik
0210 nano-technology
business
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- Scientific Reports, Scientific Reports, Vol 10, Iss 1, Pp 1-14 (2020)
- Accession number :
- edsair.doi.dedup.....23b8c962488efde8eb6a1a9cb9e10bbd