Chemical Structure of MEH-PPV/LiF/Al Interface

2002 ◽  
Vol 734 ◽  
Author(s):  
X. D. Feng ◽  
D. Grozea ◽  
Z. H. Lu
Keyword(s):  
Oxygen Concentration ◽  
Chemical Structure ◽  
Electron Injection ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
X Ray ◽  
Electron Injection Layer

ABSTRACTWe studied the poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV)/LiF/Al interface by angle-dependent X-ray photoemission spectroscopy (XPS). The changes in the C1s, O 1s, Al 2p core level spectra, and the evolution of O to C and Li to F atomic ratios at different photoelectron take-off angles were carefully analyzed. A reduced oxygen concentration with a LiF layer at the interface suggests that LiF can help reduce the oxidation of Al. The interface was found rich in Li+ ions, some of which might be attached to MEH-PPV to form “N type” doping. The electron injection layer consists of Li+doped MEH-PPV, LiF, Al oxides, and metallic Al.

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.

Photoemission Studies of the Ag/InP(110) Interface: Interfacial Reactions and Schottky Barrier Formation

1983 ◽  
Vol 25 ◽  
Author(s):  
W. G. Petro ◽  
T. Kendelewicz ◽  
I. A. Babalola ◽  
I. Lindau ◽  
W. E. Spicer
Keyword(s):  
Valence Band Maximum ◽  
Interfacial Reactions ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
Band Bending ◽  
X Ray ◽  
Barrier Formation ◽  
Deconvolution Technique ◽  
P Type ◽  
Measurable Change

ABSTRACTRoom-temperature interfacial reactions at the Ag/InP (110) interface have been studied using soft x-ray photoemission spectroscopy of the In 4d and P 2p core levels. For low Ag coverages (less than 1 monolayer (ML)) no measurable change in core level shapes is observed, and the shift in core level position is due solely to band bending. At high Ag coverages (up to 72 ML) we observe dissociated In metal, P atoms near the surface, and Ag clustering. Fermi level movement is deduced from these spectra using a deconvolution technique, and pinning positions of 0.40 ± 0.05 eV below the conduction-band minimum for n-type and 0.5 ± 0.l eV above the valence-band maximum for p-type are found. These positions are in close agreement with calculations of native defect levels.

scholarly journals Effect of Anisotropic Hybridization in YbAlB4 Probed by Linear Dichroism in Core-Level Hard X-Ray Photoemission Spectroscopy

2019 ◽  
Vol 123 (3) ◽  
Author(s):  
Kentaro Kuga ◽  
Yuina Kanai ◽  
Hidenori Fujiwara ◽  
Kohei Yamagami ◽  
Satoru Hamamoto ◽  
...  
Keyword(s):  
Linear Dichroism ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
X Ray

scholarly journals The Debye Temperature for Hydrothermally Grown ThO2 Single Crystals

2013 ◽  
Vol 1576 ◽  
Author(s):  
Tony D. Kelly ◽  
James C. Petrosky ◽  
John W. McClory ◽  
Timothy Zens ◽  
David Turner ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Single Crystals ◽  
Debye Temperature ◽  
Oxidation State ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
Temperature Dependent ◽  
X Ray ◽  
Temperature Range

ABSTRACTThe electronic properties of ThO2 single crystals were studied using x-ray photoemission spectroscopy (XPS). The XPS results show that the Th 4f core level is in an oxidation state that is consistent with that expected for Th in ThO2. The effective Debye temperature is estimated from the temperature dependent photoemission intensities of the Th 4f core level over the temperature range of 290 to 360 K. A Debye temperature of 468±32 K has been determined.

Surface and dynamical properties of GeI2

2D Materials ◽  
2021 ◽  
Author(s):  
Archit Dhingra ◽  
Alexey Lipatov ◽  
Haidong Lu ◽  
Katerina Chagoya ◽  
Joseph Dalton ◽  
...  
Keyword(s):  
Band Gap ◽  
Debye Temperature ◽  
Wide Band ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
Bulk Temperature ◽  
Level Shift ◽  
Temperature Dependent ◽  
X Ray ◽  
Optical Absorbance

Abstract GeI2 is an interesting two-dimensional (2D) wide-band gap semiconductor because of diminished edge scattering due to an absence of dangling bonds. Angle-resolved x-ray photoemission spectroscopy (ARXPS) indicates a germanium rich surface, and a surface to bulk core-level shift of 1.8 eV in binding energy, between the surface and bulk components of the Ge 2p3/2 core-level, making clear that the surface is different from the bulk. Temperature dependent studies indicate an effective Debye temperature (θD ) of 186 ± 18 K for the germanium x-ray photoemission spectroscopy (XPS) feature associated with the surface. These measurements also suggest an unusually high effective Debye temperature for iodine (587 ± 31 K), implying that iodine is present in the bulk of the material, and not the surface. From optical absorbance, GeI2 is seen to have an indirect (direct) optical band gap of 2.60 (2.8) ± 0.02 (0.1) eV, consistent with the expectations. Temperature dependent magnetometry indicates that GeI2 is moment paramagnetic at low temperatures (close to 4 K) and shows a diminishing saturation moment at high temperatures (close to 300 K and above).

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