REVERSAL OF DOPING INDUCED ENERGY LEVEL SHIFT IN ORGANIC SEMICONDUCTORS

2007 ◽  
Vol 06 (02) ◽  
pp. 125-129 ◽  
Author(s):  
HUANJUN DING ◽  
YONGLI GAO
Keyword(s):  
Electronic Structure ◽  
Energy Level ◽  
Organic Semiconductors ◽  
Energy Levels ◽  
Photoemission Spectroscopy ◽  
Level Shift ◽  
Highest Occupied Molecular Orbital ◽  
Energy Level Shift ◽  
Fine Tune ◽  
Gap State

We have investigated the electronic structure of the interface formed by depositing Au on Cs -doped and Na -doped tris(8-hydroxyquinoline) aluminum (Alq) film using ultraviolet and X-ray photoemission spectroscopy (UPS and XPS). The initial Au deposition quenches the Al q gap state caused by the alkali metal doping. Further Au depositions shift gradually the energy levels opposite to that induced by Cs doping, especially the highest occupied molecular orbital (HOMO) that shows approximately full recovery to the pristine Al q position. However, the recovery is only partial for other levels, most noticeably the C 1s core level. The results indicate that the gap state and energy level positions can be decoupled in the organic semiconductors, and that it is possible to fine tune the electronic structure by selective doping in the interface region.

scholarly journals Size-Dependent Optical Properties of Nanoscale and Bulk Long Persistent Phosphor SrAl2O4:Eu2+, Dy3+

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaoxia Duan ◽  
Lixin Yi ◽  
Xiqing Zhang ◽  
Shihua Huang
Keyword(s):  
Energy Level ◽  
Band Gap ◽  
Vacuum Ultraviolet ◽  
Surface Defects ◽  
Surface Adsorption ◽  
Trap Depth ◽  
Level Shift ◽  
Excitation Spectra ◽  
Visible Spectra ◽  
Energy Level Shift

Nanoscale long persistent phosphor SrAl2O4:Eu2+, Dy3+was prepared by autocombustion of citrate gel. The energy level shift of activator Eu2+and coactivator Dy3+was analyzed according to the emission and the excitation spectra. The band gap change of SrAl2O4and the resulting trap depth change with particle size were discussed on the basis of analyzing the visible spectra, the vacuum ultraviolet (VUV) excitation spectra, and the thermoluminescence (TL) spectra. The fluorescence quenching and the shallow traps originating from surface adsorption or surface defects explain the weak initial persistent phosphorescence and the fast phosphorescence decay in nanometer SrAl2O4:Eu2+, Dy3+. It is confirmed that energy level, band gap, trap depth, defect, and surface adsorption are deeply related with each other in this nanoscale long persistent phosphor.

Modification on the Unoccupied Electronic Structure of Organic Semiconductor by Alkali Metal

2007 ◽  
Vol 1029 ◽  
Author(s):  
Huanjun Ding ◽  
Kiwan Park ◽  
Yongli Gao
Keyword(s):  
Electronic Structure ◽  
Alkali Metal ◽  
Direct Evidence ◽  
Copper Phthalocyanine ◽  
Photoemission Spectroscopy ◽  
Inverse Photoemission ◽  
Lowest Unoccupied Molecular Orbital ◽  
Inverse Photoemission Spectroscopy ◽  
Doping Ratio ◽  
Gap State

AbstractWe have investigated the evolution of both the occupied and unoccupied states for alkali metal (Cs and Na) doped Copper-Phthalocyanine (CuPc) with photoemission and inverse photoemission spectroscopy. As the doping ratio increases, the lowest unoccupied molecular orbital (LUMO) of CuPc shifts downward, reaching the Fermi level. After the saturation, the LUMO intensity decreases monotonically, while a gap state grows in the valence spectra, which gives direct evidence for the origin of the doping-induced gap state in CuPc molecules.

scholarly journals Estimate of theσKN(I=1)(0)-term value from the energy-level shift of kaonic hydrogen in the ground state

2006 ◽  
Vol 73 (3) ◽  
Author(s):  
A. N. Ivanov ◽  
M. Faber ◽  
V. A. Ivanova ◽  
J. Marton ◽  
N. I. Troitskaya
Keyword(s):  
Energy Level ◽  
Ground State ◽  
Level Shift ◽  
Kaonic Hydrogen ◽  
Energy Level Shift

Cs doping and energy level shift in CuPc

2003 ◽  
Vol 380 (3-4) ◽  
pp. 451-455 ◽  
Author(s):  
Yongli Gao ◽  
Li Yan
Keyword(s):  
Energy Level ◽  
Level Shift ◽  
Energy Level Shift

Nonstationary Casimir effect and oscillator energy level shift

1989 ◽  
Vol 142 (8-9) ◽  
pp. 511-513 ◽  
Author(s):  
V.V. Dodonov ◽  
A.B. Klimov ◽  
V.I. Man'ko
Keyword(s):  
Energy Level ◽  
Casimir Effect ◽  
Level Shift ◽  
Energy Level Shift ◽  
Nonstationary Casimir Effect

scholarly journals Kekulene: On-Surface Synthesis, Orbital Structure, and Aromatic Stabilization

2020 ◽  
Author(s):  
Anja Haags ◽  
Alexander Reichmann ◽  
Qitang Fan ◽  
Larissa Egger ◽  
Hans Kirschner ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Photoemission Spectroscopy ◽  
Scanning Tunneling ◽  
Orbital Structure ◽  
Tunneling Microscopy ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Highest Occupied Molecular Orbital ◽  
Shed Light ◽  
Aromatic Stabilization

We revisit the question of kekulene’s aromaticity by focusing on the electronic structure of its frontier orbitals as determined by angle-resolved photoemission spectroscopy. To this end, we have developed a specially designed precursor, 1,4,7(2,7)-triphenanthrenacyclononaphane-2,5,8-triene, which allows us to prepare sufficient quantities of kekulene of high purity directly on a Cu(111) surface, as confirmed by scanning tunneling microscopy. Supported by density functional calculations, we determine the orbital structure of kekulene’s highest occupied molecular orbital by photoelectron tomography. In agreement with a recent aromaticity assessment of kekulene based solely on C–C bond lengths, we conclude that the π-conjugation of kekulene is better described by the Clar model rather than a superaromatic model. Thus, by exploiting the capabilities of photoemission tomography, we shed light on the question which consequences aromaticity holds for the frontier electronic structure of a π-conjugated molecule.<br>

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