Optical Properties and Electronic Structures of Sexithiophene

2010 ◽  
Vol 428-429 ◽  
pp. 475-478 ◽  
Author(s):  
Bao Gai Zhai ◽  
Yuan Ming Huang
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Ultraviolet Light ◽  
Organic Semiconductor ◽  
Electronic Structures ◽  
Light Emission ◽  
Visible Spectroscopy ◽  
Time Resolved ◽  
Pump And Probe ◽  
Green Photoluminescence

The optical properties and electronic structures of an organic semiconductor sexithiophene have been investigated with ultraviolet-visible spectroscopy, cw photospectroscopy and time-resolved photospectroscopy, respectively. Sexithiophene in dilute tetrahydrofuran solutions can absorb photons at 400 nm while it can give off strong green photoluminescence at 550 nm under the excitation of 325 nm ultraviolet light. With the assistance of calculated electronic structures and pump-and-probe characterization, our results indicate that both the optical absorption and the light emission of the sexithiophene are controlled by the p-conjugation of the oligothiophene.

scholarly journals Comparative Study on Electronic Structure and Optical Properties of α-Fe2O3, Ag/α-Fe2O3 and S/α-Fe2O3

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 424
Author(s):  
Cuihua Zhao ◽  
Baishi Li ◽  
Xi Zhou ◽  
Jianhua Chen ◽  
Hongqun Tang
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Electronic Structures ◽  
Density Functional ◽  
Peak Strength ◽  
Visible Range ◽  
High Symmetry ◽  
Functional Theory ◽  
Optical Absorption Peak ◽  
Calculation Results

The electronic structures and optical properties of pure, Ag-doped and S-doped α-Fe2O3 were studied using density functional theory (DFT). The calculation results show that the structure of α-Fe2O3 crystal changes after Ag and S doping, which leads to the different points of the high symmetry of Ag-doped and S-doped α-Fe2O3 with that of pure α-Fe2O3 in the energy band, as well as different Brillouin paths. In addition, the band gap of α-Fe2O3 becomes smaller after Ag and S doping, and the optical absorption peak shifts slightly toward the short wavelength, with the increased peak strength of S/α-Fe2O3 and the decreased peak strength of Ag/α-Fe2O3. However, the optical absorption in the visible range is enhanced after Ag and S doping compared with that of pure α-Fe2O3 when the wavelength is greater than 380 nm, and the optical absorption of S-doped α-Fe2O3 is stronger than that of Ag-doped α-Fe2O3.

Reversible Changes in the Electronic and Optical Properties of Micro-Crystalline ln2O 3-x: A Comparison with Amorphous In2O3-x

1996 ◽  
Vol 426 ◽  
Author(s):  
B. Pashmakov ◽  
H. Fritzsche ◽  
B. Claflin
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Absorption Coefficient ◽  
Ultraviolet Light ◽  
Indium Oxide ◽  
Electrical Conductance ◽  
Inert Gas ◽  
Optical Absorption Coefficient ◽  
Electronic And Optical Properties

AbstractThe electrical conductance and optical absorption coefficient of microcrystalline indium oxide (c – In2 O 3-x ) can be changed reversibly by several orders of magnitude by photoreduction and reoxidation. Photoreduction is achieved by exposure to ultraviolet light hv ≥ 3.5eV in vacuum or an inert gas. The effects are similar to those previously observed in amorphous In2 O3-x

Tuning band gap and optical properties of SnX2 nanosheets: Hybrid functional studies

2016 ◽  
Vol 30 (10) ◽  
pp. 1650120 ◽  
Author(s):  
P. Guo ◽  
Y. W. Luo ◽  
Y. Jia
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Band Gap ◽  
Electronic Structures ◽  
Threshold Values ◽  
Hybrid Functional ◽  
Functional Studies ◽  
Quantum Size ◽  
Light Activity ◽  
Optical Applications

Based on hybrid functional calculations, the electronic structures and optical properties are investigated in the monolayer and bilayer tin dichalcogenides SnX2 (X = S and Se) nanosheets. Numerical results show that quantum size effects are obvious on the electronic structures and optical absorption in the SnS2 and SnSe2 nanosheets. The band gap values increase when the nanosheets layer numbers decrease. Moreover, for SnSe2 nanosheet, the optical absorption coefficients are high and its threshold values lie in the visible light activity range. These results are interesting and indicate that SnS2 and SnSe2 nanosheets may serve as the promising candidates for visible optical applications.

Electronic Structure and Optical Properties of ZnO with Antisite Defects

2013 ◽  
Vol 341-342 ◽  
pp. 301-306
Author(s):  
X.J. Xie ◽  
W.H. Wang ◽  
L.Y. Li ◽  
X.G. Luo ◽  
Y.H. Cheng
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Optical Absorption ◽  
Electronic Structures ◽  
Low Energy ◽  
Visible Light Region ◽  
Optical Absorption Edge ◽  
Light Region ◽  
Level Shifts ◽  
Antisite Defects

We investigate the electronic structures and optical properties of ZnO with antisite defects OZn using the density function pseudopotential method. Our results show that the Fermi level shifts into the conduction band after introducing one or two OZn defects into ZnO supercell, indicating that the system displays a metallic-like characteristic. Moreover, the antisite defects lead to a redshift of the optical absorption edge and obvious optical absorption in the visible light region. Especially, the optical properties are influenced by the configurations of two OZn defects in our considered ZnO supercell. The strongest optical absorption occurs when the two defects are connected by-Zn-O-Zn-bond in the ab plane. These findings are possibly applicable for designing new optoelectronic and photoelectrochemical devices with improved low energy light absorption.

Tuning band gaps and optical absorption of BiOCl through doping and strain: insight form DFT calculations

2017 ◽  
Vol 19 (31) ◽  
pp. 20968-20973 ◽  
Author(s):  
Le Zhang ◽  
Zhen-Kun Tang ◽  
Woon-Ming Lau ◽  
Wen-Jin Yin ◽  
Shu-Xian Hu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Dft Calculations ◽  
Electronic Structures ◽  
Band Gaps ◽  
First Principle ◽  
First Principle Calculations

Doping and strain were used to tune the electronic structures and optical properties of BiOCl using first principle calculations.

A comparison of optical properties of disc-like and spherical quantum dots

2018 ◽  
Vol 27 (03) ◽  
pp. 1850034
Author(s):  
Vildan Üstoğlu Ünal ◽  
Erem Birşey ◽  
Ertan Akşahin
Keyword(s):  
Quantum Dots ◽  
Refractive Index ◽  
Optical Properties ◽  
Optical Absorption ◽  
Electric Field ◽  
Electronic Structures ◽  
Electric Field Effect ◽  
Total Change ◽  
Absorption Increase ◽  
Mass Approximation

The optical properties of quantum dots (QDs) are of interest to many researchers. In this study, the optical coeefficients analyzed include the optical absorption, the refractive index; both the linear and nonlinear cases together with the electric field effect. The electronic structures of the disc-like and spherical QDs are calculated by using the effective-mass approximation. The results show that the total change in the refractive index and the optical absorption increase with increasing QD size, the peaks are shifted with the changing QD size. The nonlinear optical properties increase with the external electric field and the optical intensity. Comparison of QD types shows that the peaks are red-shifted for the disc-like QD and lower than those in the spherical QD case.

The Structural and Optical Properties of Self-assembled InGaN/GaN Quantum Dots Grown by Molecular Beam Epitaxy

2006 ◽  
Vol 955 ◽  
Author(s):  
Tim Michael Smeeton ◽  
Mathieu Sénès ◽  
Katherine L Smith ◽  
Stewart E Hooper ◽  
Jon Heffernan
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Light Emission ◽  
Structural And Optical Properties ◽  
Discrete Energy ◽  
Time Resolved ◽  
Transmission Electron ◽  
Z Contrast

ABSTRACTThe structural and optical properties of InGaN quantum dots grown by plasma-assisted molecular beam epitaxy (MBE) have been characterised using atomic force microscopy, high-resolution transmission electron microscopy (TEM), Z-contrast scanning TEM, micro-photoluminescence (PL), temperature dependent PL and time-resolved PL. The uncapped InGaN nano-islands have densities of ∼1.5 × 1011 cm−2, heights of (1.7 ± 1.0) nm and diameters of (10 ± 4) nm. These parameters are not substantially changed during overgrowth of a GaN cap and the resulting quantum dots have a composition of In0.15Ga0.85N. The observation of narrow luminescence peaks in micro-PL measurements proves light emission from discrete energy states and the optical properties indicate strong confinement of carriers in the quantum dots and an unusually weak impact of piezoelectric field effects.

Electronic structures and optical properties of arsenene and antimonene under strain and an electric field

2018 ◽  
Vol 6 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Huabing Shu ◽  
Yunhai Li ◽  
Xianghong Niu ◽  
JiYuan Guo
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Electric Field ◽  
Absorption Spectra ◽  
Electronic Structures ◽  
Optical Absorption Spectra

The optical absorption spectra of hexagonal arsenene (β-As) and antimonene (β-Sb).

DFT study on electronic structures and optical absorption properties of C, S cation- doped SrTiO3

Open Physics ◽  
2009 ◽  
Vol 7 (4) ◽  
Author(s):  
Jiawen Liu ◽  
Lu Wang ◽  
Jihong Liu ◽  
Tianchi Wang ◽  
Weili Qu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Visible Light ◽  
Valence Band ◽  
Electronic Structures ◽  
Function Theory ◽  
Density Function Theory ◽  
Absorption Properties ◽  
Valence Bands ◽  
Hybrid Orbitals

AbstractThe effects of C cation and S cation doping on the electronic structures and optical properties of SrTiO3 are investigated by density function theory (DFT) calculations. The calculated results reveal that the top of the valence band is predominately made up of the O 2p states for the pure SrTiO3. When SrTiO3 was doped with C cation and S cation, the top of the valence bands consists mainly of O 2p+C 2s hybrid orbitals and O 2p+S 3s hybrid orbitals, respectively. The band gap of SrTiO3 is narrowed by the doping with C cation and S cation, especially for the C and S-codoped SrTiO3. Moreover, the red shifts of the absorption edge are found by the calculated optical properties, which is consistent with reported experiment results. It is the explanation for their visible light respondency by the presence of C 2s and S 3s states on the upper edge of the valence band. All of these results can explain the good photocatalytic properties of C, S cation-codoped SrTiO3 under visible light irradiation.

Theoretical study on nanostructural modifications of the Si(111) surface

2019 ◽  
Vol 18 (01) ◽  
pp. 1950005
Author(s):  
Yue-Hang Dong ◽  
Xiao-Hui Liu ◽  
Wan-Sheng Su ◽  
Li-Zhen Zhao ◽  
Qing-Jun Zang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Optical Absorption ◽  
Dft Calculations ◽  
Electronic Structures ◽  
Density Functional ◽  
Theoretical Study ◽  
Surface Modifications ◽  
Thermal Stabilities ◽  
Functional Theory

Modified Si(111) surface with designed nanostructural modifications including grown pits, nanobars and nanoislands as well as deposited hill-, diamond- and cage-like nanoclusters were studied using density-functional theory (DFT) calculations. The thermal stabilities, electronic structures and optical properties of these various nanostructural modifications of the Si(111) surface were calculated and discussed. The results indicate that the optical absorption of the modified Si(111) surface can be enhanced by these surface modifications especially when depositing diamond-like nanoclusters on the surface.

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