Tunable electronic and dielectric properties of β-phosphorene nanoflakes for optoelectronic applications

RSC Advances ◽  
2016 ◽  
Vol 6 (104) ◽  
pp. 101835-101845 ◽  
Author(s):  
Pradeep Bhatia ◽  
Ram Swaroop ◽  
Ashok Kumar
Keyword(s):  
Density Functional Theory ◽  
Dielectric Properties ◽  
Dielectric Response ◽  
Density Functional ◽  
Energy Gap ◽  
Optoelectronic Device ◽  
Functional Theory ◽  
Device Applications ◽  
Optoelectronic Applications

Electronic and dielectric properties of β-phosphorene nanoflakes in various configurations using density functional theory are reported. The tunable energy gap and dielectric response make these nanoflakes potential candidates for optoelectronic device applications.

STRUCTURES, ABSORPTION SPECTRA, AND ELECTRONIC PROPERTIES OF POLYFLUORENE AND ITS DERIVATIVES: A THEORETICAL STUDY

2006 ◽  
Vol 05 (03) ◽  
pp. 595-608 ◽  
Author(s):  
KRIENGSAK SRIWICHITKAMOL ◽  
SONGWUT SURAMITR ◽  
POTJAMAN POOLMEE ◽  
SUPA HANNONGBUA
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Level Energy ◽  
Excitation Energies ◽  
Lumo Energy ◽  
Functional Theory ◽  
Local Energy Minimum ◽  
Pi Systems ◽  
Homo Lumo

The structural and energetic properties of polyfluorene and its derivatives were investigated, using quantum chemical calculations. Conformational analysis of bifluorene was performed by using ab initio (HF/6-31G* and MP2/6-31G*) and density functional theory (B3LYP/6-31G*) calculations. The results showed that the local energy minimum of bifluorene lies between the coplanar and perpendicular conformation, and the B3LYP/6-31G* calculations led to the overestimation of the stability of the planar pi systems. The HOMO-LUMO energy differences of fluorene oligomers and its derivatives — 9,9-dihexylfluorene (DHPF), 9,9-dioctylfluorene (PFO), and bis(2-ethylhexyl)fluorene (BEHPF) — were calculated at the B3LYP/6-31G* level. Energy gaps and effective conjugation lengths of the corresponding polymers were obtained by extrapolating HOMO-LUMO energy differences and the lowest excitation energies to infinite chain length. The lowest excitation energies and the maximum absorption wavelength of polyfluorene were also performed, employing the time-dependent density functional theory (TDDFT) and ZINDO methods. The extrapolations, based on TDDFT and ZINDO calculations, agree well with experimental results. These theoretical methods can be useful for the design of new polymeric structures with a reducing energy gap.

scholarly journals Chloroquine drug and Graphene complex for treatment of COVID-19

2020 ◽  
Author(s):  
Saeedeh Mohammadi ◽  
Mohammad Esmailpour ◽  
Mina Mohammadi
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Dft Method ◽  
Complex State ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structural And Electrical Properties ◽  
Suitable Structure ◽  
Drug Complex

Abstract This paper is a new step in helping the treatment of coronavirus by improving the performance of chloroquine drug. For this purpose, we propose a complex of chloroquine drug with graphene nanoribbon (GNR) scheme. We compute the structural and electrical properties and absorption of chloroquine (C18H26ClN3) and GNR complex using the density functional theory (DFT) method. By creating a drug and GNR complex, the density of states of electrons increases and the energy gap decreases compared to the chloroquine. Also, using absorption calculations and spectrums such as infrared and UV-Vis spectra, we showed that GNR is a suitable structure for creating chloroquine drug complex. Our results show that the dipole moment, global softness and electrophilicity for the drug complex increases compared to the non-complex state. Our calculations can be useful for increasing performance and reducing the side effects of chloroquine, and thus can be effective in treating coronavirus.

scholarly journals A NOVEL FRACTAL GEOMETRY DOPING FOR GRAPHENE NANORIBBON AND THE OPTIMIZATION OF CRYSTAL: A DENSITY FUNCTIONAL THEORY (DFT) STUDY

2020 ◽  
Vol 17 (35) ◽  
pp. 1148-1158
Author(s):  
Mohammed L. JABBAR ◽  
Kadhum J. AL-SHEJAIRY
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Minimum Energy ◽  
Graphene Nanoribbon ◽  
Chemical Doping ◽  
Functional Theory ◽  
Lower Reactivity ◽  
The Density Functional Theory ◽  
Semiconductor Behavior

Chemical doping is a promising route to engineering and controlling the electronic properties of the zigzag graphene nanoribbon (ZGNR). By using the first-principles of the density functional theory (DFT) calculations at the B3LYP/ 6-31G, which implemented in the Gaussian 09 software, various properties, such as the geometrical structure, DOS, HOMO, LUMO infrared spectra, and energy gap of the ZGNR, were investigated with various sites and concentrations of the phosphorus (P). It was observed that the ZGNR could be converted from linear to fractal dimension by using phosphorus (P) impurities. Also, the fractal binary tree of the ZGNR and P-ZGNR structures is a highlight. The results demonstrated that the energy gap has different values, which located at this range from 0.51eV to 1.158 eV for pristine ZGNR and P-ZGNR structures. This range of energy gap is variable according to the use of GNRs in any apparatus. Then, the P-ZGNR has semiconductor behavior. Moreover, there are no imaginary wavenumbers on the evaluated vibrational spectrum confirms that the model corresponds to minimum energy. Then, these results make P-ZGNR can be utilized in various applications due to this structure became more stable and lower reactivity.

A density functional theory study on the performance of graphene and N-doped graphene supported Au3 cluster catalyst for acetylene hydrochlorination

2016 ◽  
Vol 94 (10) ◽  
pp. 842-847 ◽  
Author(s):  
Fei Zhao ◽  
Yang Wang ◽  
Lihua Kang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Activation Barrier ◽  
Similar Reaction ◽  
Functional Theory ◽  
Acetylene Hydrochlorination ◽  
Doped Graphene ◽  
Calculated Activation ◽  
Calculated Activation Barrier

Density functional theory (DFT) calculation was used to investigate the mechanism of Au3 clusters, separately supported on pure graphene (Au3/graphene) and one graphitic N-doped graphene (Au3/N-graphene). These supported Au3 clusters were used to catalyze acetylene hydrochlorination. Results show that the graphene supporter could obviously enhance the adsorption of reactants. Also, N-atom doping could broaden the energy gap between the HOMO of graphene and the LUMO of Au3, leading to the significantly attenuated interaction between the Au3 cluster and graphene by more than 19 kcal/mol (1 cal = 4.184 J). The two catalysts possessed extremely similar reaction mechanisms with activation energy values of 23.26 and 23.89 kcal/mol, respectively. The calculated activation barrier declined in the order of Au3 < Au3/N-graphene < Au3/graphene, suggesting that Au3/N-graphene could be a potential catalyst for acetylene hydrochlorination.

SOLVENT EFFECTS ON THE ELECTRONIC STRUCTURE AND NON-LINEAR OPTICAL PROPERTIES OF PYRENE AND SOME OF ITS DERIVATIVES BASED ON DENSITY FUNCTIONAL THEORY

2021 ◽  
Vol 4 (4) ◽  
pp. 236-251
Author(s):  
A. S. Gidado ◽  
L. S. Taura ◽  
A. Musa
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Chemical Reactivity ◽  
Basis Set ◽  
Lumo Energy ◽  
Functional Theory ◽  
Organic Optoelectronic ◽  
Homo Lumo

Pyrene (C16H10) is an organic semiconductor which has wide applications in the field of organic electronics suitable for the development of organic light emitting diodes (OLED) and organic photovoltaic cells (OPV). In this work, Density Functional Theory (DFT) using Becke’s three and Lee Yang Parr (B3LYP) functional with basis set 6-311++G(d, p) implemented in Gaussian 03 package was  used to compute total energy, bond parameters, HOMO-LUMO energy gap, electron affinity, ionization potential, chemical reactivity descriptors, dipole moment, isotropic polarizability (α), anisotropy of polarizability ( Δ∝) total first order hyper-polarizability () and second order hyperpolarizability (). The molecules used are pyrene, 1-chloropyrene and 4-chloropyrene  in gas phase and in five different solvents: benzene, chloroform, acetone, DMSO and water. The results obtained show that solvents and chlorination actually influenced the properties of the molecules. The isolated pyrene in acetone has the largest value of HOMO-LUMO energy gap of and is a bit closer to a previously reported experimental value of  and hence is the most stable. Thus, the pyrene molecule has more kinetic stability and can be described as low reactive molecule. The calculated dipole moments are in the order of 4-chloropyrene (1.7645 D) < 1-chloropyrene (1.9663 D) in gas phase. The anisotropy of polarizability ( for pyrene and its derivatives were found to increase with increasing polarity of the solvents.  In a nutshell, the molecules will be promising for organic optoelectronic devices based on their computed properties as reported by this work.

Studying of B, N, S, Si and P Doped (5, 5) Carbon Nanotubes by the Density Functional Theory

2012 ◽  
Vol 463-464 ◽  
pp. 1488-1492 ◽  
Author(s):  
Yan Li Wang ◽  
Ke He Su ◽  
Jun Ping Zhang
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional Theory ◽  
Density Functional ◽  
Periodic Boundary ◽  
Energy Gap ◽  
Periodic Boundary Conditions ◽  
Functional Theory ◽  
Energy Gaps ◽  
The Density Functional Theory ◽  
Metal Conductivity

The B, N, S, Si and P atoms doped single walled (5, 5) carbon nanotubes were studied by density functional theory B3LYP/3-21G (d) with the periodic boundary conditions. The ultra long tube models were calculated and the structures, energies and the band structures were obtained. The N, Si and S doped nanotubes have narrow energy gap with metal conductivity whereas B and P doped nanotubes have overlapped energy gaps with or semi-metal conductivity.

Cyclodextrins Stabilize TOPO-(CdSe)ZnS Quantum Dots In Water

2004 ◽  
Vol 823 ◽  
Author(s):  
Jun Feng ◽  
Yong-Hyun Kim ◽  
S. B. Zhang ◽  
Shi-You Ding ◽  
Melvin P. Tucker ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
First Principles ◽  
Density Functional ◽  
Water Soluble ◽  
Hydroxyl Group ◽  
Functional Theory ◽  
Chemical Action ◽  
Coordinate Bond ◽  
Device Applications

AbstractChemical action between cyclodextrins (CDs) and TOPO-(CdSe)ZnS quantum dots (QDs) generates a water-soluble solution of CD-QDs. Hydrophobic TOPO molecules on surface of the QDs are compatible to thread through the pockets of CDs and make the hydroxyl group on end of CDs to approach the ZnS surface, and then cause the interaction between ZnS and the hydroxyls. In this paper, Photoluminescence of the γ-CD-QD solution appeared about 15 nm of red movement compared with that of the QDs in hexane; 58% replacement of the crystal coordinate bond of Zn-S with that of Zn-O in the ZnS shell was demonstrated by using first-principles density functional theory and the red shift of the photoluminescence of CD-QDs; and –0.11eV of the energy gain of the exchange model was calculated by using an effective mass (EM) model. CD-QDs will provide water-soluble QDs with conjugational group for biology and molecule-device applications.

scholarly journals Theoretical Study of a Class of Organic D-π-A Dyes for Polymer Solar Cells: Influence of Various π-Spacers

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 163
Author(s):  
Nguyen Van Trang ◽  
Tran Ngoc Dung ◽  
Ngo Tuan Cuong ◽  
Le Thi Hong Hai ◽  
Daniel Escudero ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Solar Cells ◽  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Polymer Solar Cells ◽  
Basis Set ◽  
Structure Theory ◽  
Functional Theory ◽  
Alkyl Groups

A class of D-π-A compounds that can be used as dyes for applications in polymer solar cells has theoretically been designed and studied, on the basis of the dyes recently shown by experiment to have the highest power conversion efficiency (PCE), namely the poly[4,8-bis(5-(2-butylhexylthio)thiophen-2-yl)benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl-alt-TZNT] (PBDTS-TZNT) and poly[4,8-bis(4-fluoro-5-(2-butylhexylthio)thiophen-2-yl)benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl-alt-TZNT] (PBDTSF-TZNT) substances. Electronic structure theory computations were carried out with density functional theory and time-dependent density functional theory methods in conjunction with the 6−311G (d, p) basis set. The PBDTS donor and the TZNT (naphtho[1,2-c:5,6-c]bis(2-octyl-[1,2,3]triazole)) acceptor components were established from the original substances upon replacement of long alkyl groups within the thiophene and azole rings with methyl groups. In particular, the effects of several π-spacers were investigated. The calculated results confirmed that dithieno[3,2-b:2′,3′-d] silole (DTS) acts as an excellent π-linker, even better than the thiophene bridge in the original substances in terms of well-known criteria. Indeed, a PBDTS-DTS-TZNT combination forms a D-π-A substance that has a flatter structure, more rigidity in going from the neutral to the cationic form, and a better conjugation than the original compounds. The highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gap of such a D-π-A substance becomes smaller and its absorption spectrum is more intense and red-shifted, which enhances the intramolecular charge transfer and makes it a promising candidate to attain higher PCEs.

Optical and dielectric properties of lead perovskite and iodoplumbate complexes: an ab initio study

2020 ◽  
Vol 22 (33) ◽  
pp. 18423-18434
Author(s):  
Malladi Srikanth ◽  
Mailde S. Ozório ◽  
Juarez L. F. Da Silva
Keyword(s):  
Density Functional Theory ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Optical Dielectric Constant ◽  
Energetic Stability ◽  
Optical Dielectric

Optical and dielectric properties, and energetic stability orders of black phase of perovskites and yellow phase of iodoplumbates have been studied using density functional theory; where the optical dielectric constant varies with the polymorphic phase and nature of cation.

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