Electronic and Optical Properties of Polythiophene Molecules and Derivatives

The electronic and optical properties of polythiophene (PT) for polymer light-emitting diodes (PLEDs) were calculated using density functional theory (DFT) and time-dependent DFT. We calculated the electronic and optical properties of thiophene and PT polymers with degrees of polymerization (DP) from 2 to 30 monomers (T1–T30) and their derivatives. The associated highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy, band gaps, electron orbitals, and molecular structures were determined. As the DP increased, the LUMO energy gradually decreased, and the HOMO energy gradually increased. The band gap of PT approached 2 eV as the DP of the PT polymer increased from 1 to 30. The calculations and exchange–correlation functional were verified against values in the literature and experimental data from cyclic voltammetry (redox potential) and ultraviolet-visible, photoluminescence, and ultraviolet photoelectron spectra. The color of PT PLEDs can be adjusted by controlling the DP of the polymer and the substituents.

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Theoretical studies on lindqvist polyoxometalates [M6O19]n−(M = Mo, W, n=2; M = V, Nb, Ta, n=8) and derivatives: Electronic structures, stability and bonding

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633617500547 ◽

2017 ◽

Vol 16 (06) ◽

pp. 1750054 ◽

Cited By ~ 2

Author(s):

Xiao-Fang Su ◽

Bo Zhu ◽

Cai-Xia Wu ◽

Li-Kai Yan ◽

Zhong-Min Su

Keyword(s):

Charge Density ◽

Molecular Orbital ◽

Electronic Structures ◽

Density Functional ◽

Geometrical Structure ◽

Energy Gap ◽

Lumo Energy ◽

Functional Theory ◽

Highest Occupied Molecular Orbital ◽

Lowest Unoccupied Molecular Orbital

The geometrical and electronic structures of [M6O[Formula: see text]][Formula: see text] (M [Formula: see text] Mo, W, [Formula: see text]; M [Formula: see text] V, Nb, Ta, [Formula: see text]) and their derivatives were investigated by using density functional theory methods. The results indicate that the geometrical structure of [V6O[Formula: see text]][Formula: see text] is not different from other Lindqvist-type anions. The energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) (HOMO[Formula: see text]LUMO energy gap) of [V6O[Formula: see text]][Formula: see text] is smaller than those of same charge anions, [Nb6O[Formula: see text]][Formula: see text] and [Ta6O[Formula: see text]][Formula: see text]. In addition, the charge density [Formula: see text] of [V6O[Formula: see text]][Formula: see text] is larger when compared with those of other studied clusters. The investigation on the derivatives shows that the valence of V atom (V[Formula: see text] or V[Formula: see text]) and the methoxy ligand influence the HOMO[Formula: see text]LUMO energy gap and the charge density [Formula: see text] of the studied clusters.

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Effect of Host Moieties on the Phosphorescent Spectrum of Green Platinum Complex

Molecules ◽

10.3390/molecules24030454 ◽

2019 ◽

Vol 24 (3) ◽

pp. 454 ◽

Cited By ~ 3

Author(s):

Yukiko Iwasaki ◽

Hirohiko Fukagawa ◽

Takahisa Shimizu

Keyword(s):

Emission Spectrum ◽

Molecular Orbital ◽

Platinum Complex ◽

Delayed Fluorescence ◽

Molecular Structures ◽

Light Emitting ◽

Exciplex Formation ◽

Highest Occupied Molecular Orbital ◽

Wide Color Gamut ◽

Lowest Unoccupied Molecular Orbital

Highly efficient, operationally stable, and pure-color organic light-emitting diodes (OLEDs) are of considerable significance for developing practical wide-color-gamut displays. Further, we have demonstrated the feasibility of an efficient pure green phosphorescent OLED (PHOLED) by employing a narrow-band platinum complex and a top-emitting structure. The utilization of the thermally activated delayed fluorescence (TADF) material as the phosphorescent host is expected to serve as a promising solution for obtaining operationally stable PHOLEDs with high color purity. However, the emission spectrum of the platinum complex in the TADF host exhibits a considerably broad emission spectrum. This study investigates the cause of the spectral change by evaluating the photoluminescence spectra of the platinum complex in various hosts exhibiting different molecular structures. The triazine unit in the host material was observed to result in exciplex formation between the lowest unoccupied molecular orbital (LUMO) of the host and the highest occupied molecular orbital (HOMO) of the platinum complex. Therefore, the TADF material that sterically hinders the triazine unit is considered to be suitable to prevent both exciplex formation and spectral broadening.

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First principles calculation of structural, electronic and optical properties of (001) and (110) growth axis (InN)/(GaN)n superlattices

Revista Mexicana de Física ◽

10.31349/revmexfis.67.7 ◽

2021 ◽

Vol 67 (1 Jan-Feb) ◽

pp. 7

Author(s):

B. Bachir Bouiadjra ◽

N. Mehnane ◽

N. Oukli

Keyword(s):

Optical Properties ◽

Density Functional ◽

Electronic Band Structure ◽

Scale Up ◽

Energy Scale ◽

First Principles Calculation ◽

Full Potential ◽

Electronic Band ◽

Electronic And Optical Properties ◽

Growth Axis

Based on the full potential linear muffin-tin orbitals (FPLMTO) calculation within density functional theory, we systematically investigate the electronic and optical properties of (100) and (110)-oriented (InN)/(GaN)n zinc-blende superlattice with one InN monolayer and with different numbers of GaN monolayers. Specifically, the electronic band structure calculations and their related features, like the absorption coefficient and refractive index of these systems are computed over a wide photon energy scale up to 20 eV. The effect of periodicity layer numbers n on the band gaps and the optical activity of (InN)/(GaN)n SLs in the both growth axis (001) and (110) are examined and compared. Because of prospective optical aspects of (InN)/(GaN)n such as light-emitting applications, this theoretical study can help the experimental measurements.

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Influence on structural, electronic and optical properties of Fe doped ZnS quantum dot: A density functional theory based study

International Journal of Quantum Chemistry ◽

10.1002/qua.26786 ◽

2021 ◽

Author(s):

Md. Abdul Momin ◽

Md. Aminul Islam ◽

Abhijit Majumdar

Keyword(s):

Density Functional Theory ◽

Optical Properties ◽

Quantum Dot ◽

Density Functional ◽

Functional Theory ◽

Electronic And Optical Properties

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Electronic and optical properties of vacancy ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; and X = Cl, Br, I): a first principles study

Scientific Reports ◽

10.1038/s41598-021-86145-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Muhammad Faizan ◽

K. C. Bhamu ◽

Ghulam Murtaza ◽

Xin He ◽

Neeraj Kulhari ◽

...

Keyword(s):

Optical Properties ◽

Band Gap ◽

First Principles ◽

Density Functional ◽

Perovskite Solar Cells ◽

Dielectric Constants ◽

Maximum Efficiency ◽

Exchange Potential ◽

Double Perovskites ◽

Electronic And Optical Properties

AbstractThe highly successful PBE functional and the modified Becke–Johnson exchange potential were used to calculate the structural, electronic, and optical properties of the vacancy-ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; X = Cl, Br, and I) using the density functional theory, a first principles approach. The convex hull approach was used to check the thermodynamic stability of the compounds. The calculated parameters (lattice constants, band gap, and bond lengths) are in tune with the available experimental and theoretical results. The compounds, Rb2PdBr6 and Cs2PtI6, exhibit band gaps within the optimal range of 0.9–1.6 eV, required for the single-junction photovoltaic applications. The photovoltaic efficiency of the studied materials was assessed using the spectroscopic-limited-maximum-efficiency (SLME) metric as well as the optical properties. The ideal band gap, high dielectric constants, and optimum light absorption of these perovskites make them suitable for high performance single and multi-junction perovskite solar cells.

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Structural, Electronic, and Optical Properties of Group 6 Doped Anatase TiO2: A Theoretical Approach

Applied Sciences ◽

10.3390/app11041657 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1657

Author(s):

Petros-Panagis Filippatos ◽

Nikolaos Kelaidis ◽

Maria Vasilopoulou ◽

Dimitris Davazoglou ◽

Alexander Chroneos

Keyword(s):

Optical Properties ◽

Solar Cells ◽

Electron Transport ◽

Density Functional ◽

Perovskite Solar Cells ◽

Solar Spectrum ◽

Type Conductivity ◽

Electronic And Optical Properties ◽

Group 6 ◽

Visible Wavelengths

Titania (TiO2) is a key material used as an electron transport in dye-sensitized and halide perovskite solar cells due to its intrinsic n-type conductivity, visible transparency, low-toxicity, and abundance. Moreover, it exhibits pronounced photocatalytic properties in the ultra-violet part of the solar spectrum. However, its wide bandgap (around 3.2 eV) reduces its photocatalytic activity in the visible wavelengths’ region and electron transport ability. One of the most efficient strategies to simultaneously decrease its bandgap value and increase its n-type conductivity is doping with appropriate elements. Here, we have investigated using the density functional theory (DFT), as well as the influence of chromium (Cr), molybdenum (Mo), and tungsten (W) doping on the structural, electronic, and optical properties of TiO2. We find that doping with group 6 elements positively impacts the above-mentioned properties and should be considered an appropriate method for photocatalystic applications. In addition to the pronounced reduction in the bandgap values, we also predict the formation of energy states inside the forbidden gap, in all the cases. These states are highly desirable for photocatalytic applications as they induce low energy transitions, thus increasing the oxide’s absorption within the visible. Still, they can be detrimental to solar cells’ performance, as they constitute trap sites for photogenerated charge carriers.

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