Built-in Potential of a Pentacene Pin Homojunction Studied by Ultraviolet Photoemission Spectroscopy

2010 ◽  
Vol 1270 ◽  
Author(s):  
Selina Olthof ◽  
Hans Kleemann ◽  
Björn Lüssem ◽  
Karl Leo
Keyword(s):  
Small Molecules ◽  
Work Function ◽  
Photoelectron Spectroscopy ◽  
Photoemission Spectroscopy ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Organic P ◽  
Band Bending ◽  
Silver Substrate ◽  
N Doping ◽  
Ultraviolet Photoemission Spectroscopy

AbstractIn this paper we investigate the energetic alignment in an organic p-i-n homojunction using ultraviolet photoelectron spectroscopy. The device is made of pentacene and we emploay the small molecules NDN1 for n-doping and NDP2 for p-doping the layers. The full p-i-n structure is deposited stepwise on a silver substrate to learn about the interface dipoles and band bending effects present in the device. From the change in work function between the p- and n-doped layers we gain knowledge of the built-in potential of this junction.

CdS and Cd-Free Buffer Layers on Solution Phase Grown Cu2ZnSn(SxSe1- x)4 :Band Alignments and Electronic Structure Determined with Femtosecond Ultraviolet Photoelectron Spectroscopy

2014 ◽  
Vol 1638 ◽  
Author(s):  
Richard Haight ◽  
Aaron Barkhouse ◽  
Wei Wang ◽  
Yu Luo ◽  
Xiaoyan Shao ◽  
...  
Keyword(s):  
Fermi Level ◽  
Photoelectron Spectroscopy ◽  
Solution Phase ◽  
Buffer Layers ◽  
Photoemission Spectroscopy ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Band Bending ◽  
Pump Probe ◽  
Fermi Level Pinning ◽  
Band Alignments

ABSTRACTThe heterojunctions formed between solution phase grown Cu2ZnSn(SxSe1- x)4 (CZTS,Se) and a number of important buffer materials including CdS, ZnS, ZnO, and In2S3, were studied using femtosecond ultraviolet photoemission spectroscopy (fs-UPS) and photovoltage spectroscopy. With this approach we extract the magnitude and direction of the CZTS,Se band bending, locate the Fermi level within the band gaps of absorber and buffer and measure the absorber/buffer band offsets under flatband conditions. We will also discuss two-color pump/probe experiments in which the band bending in the buffer layer can be independently determined. Finally, studies of the bare CZTS,Se surface will be discussed including our observation of mid-gap Fermi level pinning and its relation to Voc limitations and bulk defects.

scholarly journals Thermal Stability of Octadecyltrichlorosilane and Perfluorooctyltriethoxysilane Monolayers on SiO2

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 210
Author(s):  
Xiangdong Yang ◽  
Haitao Wang ◽  
Peng Wang ◽  
Xuxin Yang ◽  
Hongying Mao
Keyword(s):  
Thermal Stability ◽  
Thermal Behavior ◽  
Work Function ◽  
Photoelectron Spectroscopy ◽  
Vacuum Annealing ◽  
Moderate Temperature ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
X Ray ◽  
Thermal Stability Of

Using in situ ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) measurements, the thermal behavior of octadecyltrichlorosilane (OTS) and 1H, 1H, 2H, and 2H-perfluorooctyltriethoxysilane (PTES) monolayers on SiO2 substrates has been investigated. OTS is thermally stable up to 573 K with vacuum annealing, whereas PTES starts decomposing at a moderate temperature between 373 K and 423 K. Vacuum annealing results in the decomposition of CF3 and CF2 species rather than desorption of the entire PTES molecule. In addition, our UPS results reveal that the work function (WF)of OTS remains the same after annealing; however WF of PTES decreases from ~5.62 eV to ~5.16 eV after annealing at 573 K.

Role of Surfaces and Interfaces for the Electronic Properties of Conducting Oxides

2001 ◽  
Vol 666 ◽  
Author(s):  
Andreas Klein
Keyword(s):  
Work Function ◽  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Band Alignment ◽  
Surface Band ◽  
Band Bending ◽  
Conducting Oxides ◽  
Degenerate Semiconductors ◽  
Surfaces And Interfaces

ABSTRACTTransparent conductive oxides (TCOs) are generally considered as degenerate semiconductors doped intrinsically by oxygen vacancies and by intentionally added dopants. For some applications a high work function is required in addition to high conductivity and it is desired to tune both properties independently. To increase the work function, the distance between the Fermi energy and the vacuum level must increase, which can be realized either by electronic surface dipoles or by space charge layers. Photoelectron spectroscopy data of in-situ prepared samples clearly show that highly doped TCOs can show surface band bending of the order of 1 eV. It is further shown that the band alignment at heterointerfaces between TCOs and other materials, which are crucial for many devices, are also affected by such band bending. The origin of the band bending, which seems to be general to all TCOs, depends on TCO thin film and surface processing conditions. The implication of surface band bending on the electronic properties of thin films and interfaces are discussed.

THE ADSORPTION AND DESORPTION OF OXYGEN ON CdZnTe (111)B-(2 × 2) SURFACE

2013 ◽  
Vol 20 (03n04) ◽  
pp. 1320001
Author(s):  
XUXU BAI ◽  
WANQI JIE ◽  
GANGQIANG ZHA ◽  
WENHUA ZHANG ◽  
JUNFA ZHU ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Photoelectron Spectroscopy ◽  
Oxygen Adsorption ◽  
Photoemission Spectroscopy ◽  
Adsorption And Desorption ◽  
X Ray ◽  
Oxygen Exposure ◽  
Surface Work ◽  
Ultraviolet Photoemission Spectroscopy ◽  
Surface Work Function

The oxygen adsorption and desorption on the CdZnTe (111) B -(2×2) surface were studied with synchrotron radiation ultraviolet photoemission spectroscopy (SRUPS) and X-ray photoelectron spectroscopy (XPS). The results show that a surface state of clean CdZnTe (111) B -(2×2) surface appears at 0.5 eV below Fermi level ( E F), which disappears after the oxygen exposure, and shows again after annealing in UHV. The surface work function of CdZnTe (111) B -(2×2) decreases after the oxygen exposure, and futher reduces after annealing.

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