CHARGE TRANSFER AND DIELECTRIC PROPERTIES OF TiO2–GRAPHENE COMPOSITES

2012 ◽  
Vol 02 (01) ◽  
pp. 1250004
Author(s):  
CAI-HUA ZHOU ◽  
QIAN XU ◽  
SHENG-TAO LI ◽  
XIANG ZHAO
Keyword(s):  
Charge Transfer ◽  
Dielectric Properties ◽  
Density Functional ◽  
Dielectric Constants ◽  
Potential Density ◽  
Functional Theory ◽  
Transfer Properties ◽  
Pseudo Potential ◽  
Interfacial Charge ◽  
Atomic Type

The electronic structures and dielectric properties of TiO2 –graphene composites are studied using pseudo-potential density functional theory. It is shown that interfacial charge transfer properties of graphene/ TiO2 are influenced by the atomic type on TiO2 surface. The interfacial interaction of graphene with Ti -terminated surface is so strong that it causes a buckling structural graphene, and the titanium atomic d electrons are transferred obviously from TiO2 to graphene. It is revealed that dielectric properties of the composites are greatly affected by both band structures and electronic transitions. Compared with bulk TiO2 , dielectric constants of TiO2 –graphene composites are significantly improved.

Structural, Thermodynamic, Elastic, and Electronic Properties of α-SnS at High Pressure from First-Principles Investigations

2015 ◽  
Vol 70 (11) ◽  
pp. 949-960 ◽  
Author(s):  
Chun Mei Liu ◽  
Chao Xu ◽  
Man Yi Duan
Keyword(s):  
Experimental Data ◽  
Electronic Properties ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Energy Relation ◽  
Potential Density ◽  
Functional Theory ◽  
Free Energy Relation ◽  
Similar Growth ◽  
Pseudo Potential

AbstractSnS has potential technical applications, but many of its properties are still not well studied. In this work, the structural, thermodynamic, elastic, and electronic properties of α-SnS have been investigated by the plane wave pseudo-potential density functional theory with the framework of generalised gradient approximation. The calculated pressure-dependent lattice parameters agree well with the available experimental data. Our thermodynamic properties of α-SnS, including heat capacity CP , entropy S, and Gibbs free energy relation of –(GT –H0) curves, show similar growth trends as the experimental data. At T=298.15 K, our CP =52.31 J/mol·K, S=78.93 J/mol·K, and –(GT –H0)=12.03 J/mol all agree very well with experimental data CP =48.77 J/mol·K and 49.25 J/mol·K, S=76.78 J/mol·K, and –(GT –H0)=12.38 J/mol. The elastic constants, together with other elastic properties, are also computed. The anisotropy analyses indicate obvious elastic anisotropy for α-SnS along different symmetry planes and axes. Moreover, calculations demonstrate that α-SnS is an indirect gap semiconductor, and it transforms to semimetal with pressure increasing up to 10.2 GPa. Combined with the density of states, the characters of the band structure have been analysed in detail.

Adsorption and Light Absorption Properties of 2-Anthroic Acid on Titania: a Density Functional Theory – Time-Dependent Density Functional Theory Study

MRS Advances ◽  
2016 ◽  
Vol 1 (41) ◽  
pp. 2795-2800
Author(s):  
Sergei Manzhos ◽  
Konstantinos Kotsis
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Light Absorption ◽  
Density Functional ◽  
Dye Sensitized Solar Cells ◽  
Band Alignment ◽  
Absorption Properties ◽  
Functional Theory ◽  
Interfacial Charge Transfer ◽  
Interfacial Charge

ABSTRACTThe adsorption 2-anthroic acid on titania has been shown to result in an interfacial charge transfer band, which makes this a promising interface for dye-sensitized solar cells with direct injection. Here, we model the adsorption of 2-anthroic acid on a TiO2 nanocluster exhibiting a (101)-like interface and compute light absorption properties of this system using for the first time a hybrid functional. The band alignment and the formation of interfacial charge transfer bands proposed in previous experimental and lower-level computational works are confirmed.

A study on the electronic and charge transfer properties in tin phthalocyanine (SnPc) derivatives by density functional theory

2011 ◽  
Vol 977 (1-3) ◽  
pp. 9-12 ◽  
Author(s):  
Ahmad Irfan ◽  
Abdullah G. Al-Sehemi ◽  
Abdullah M. Asiri ◽  
Muhammad Nadeem ◽  
Khalid A. Alamry
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Density Functional ◽  
Functional Theory ◽  
Transfer Properties

Theoretical investigation of elastic and phononic properties of Zn1−xBexO alloys

2015 ◽  
Vol 29 (24) ◽  
pp. 1550140 ◽  
Author(s):  
F. Elhamra ◽  
S. Lakel ◽  
M. Ibrir ◽  
K. Almi ◽  
H. Meradji
Keyword(s):  
Density Functional ◽  
Phonon Dispersion ◽  
Local Density ◽  
Molar Fraction ◽  
Dielectric Constants ◽  
Functional Theory ◽  
Phonon Dispersion Curves ◽  
Density Functional Perturbation Theory ◽  
Pseudo Potential ◽  
Born Effective Charge

Our calculations were conducted within density functional theory (DFT) and density functional perturbation theory (DFPT) using norm-conserving pseudo-potential and the local density approximation. The elastic constants of [Formula: see text] were calculated, [Formula: see text], [Formula: see text] and [Formula: see text] increase with the increase of Be content, whereas the [Formula: see text] shows a non-monotonic variation and [Formula: see text] decreases when Be concentration increases. The values of bulk modulus [Formula: see text], Young’s modulus [Formula: see text] and shear modulus [Formula: see text] increase with the increase of Be content. Poisson’s ratio [Formula: see text] decreases with increased Be concentration. The ductility decreases with increasing Be concentration and the compressibility for [Formula: see text] along [Formula: see text]-axis is smaller than along [Formula: see text]-axis. Phonon dispersion curves show that [Formula: see text] is dynamically stable (no soft modes). Quantities such as refractive index, Born effective charge, dielectric constants and optical phonon frequencies were calculated as a function of the Be molar fraction [Formula: see text]. The agreement between the present results and the known data that are available only for ZnO and BeO is generally satisfactory. Our results for [Formula: see text] [Formula: see text] are predictions.

Ferroelectric Ba0.75Sr0.25TiO3 tunable charge transfer in perovskite devices

2021 ◽  
Author(s):  
Zi-Xuan Chen ◽  
Jia-Lin Sun ◽  
Qiang Zhang ◽  
Chong-Xin Qian ◽  
Ming-Zi Wang ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Perovskite Solar Cells ◽  
Charge Carriers ◽  
Ferroelectric Polarization ◽  
Functional Theory ◽  
Interfacial Charge Transfer ◽  
Electron Transporting Layer ◽  
Interfacial Charge ◽  
Film Conductivity

Abstract Interfacial charge recombination is a main issue causing the efficiency loss of the perovskite solar cells (PSCs). Here, ferroelectric Ba0.75Sr0.25TiO3 (BST) is introduced as a polarization tunable layer to promote the interfacial charge transfer of the PSCs. The coexistence of ferroelectric polarization and charge carriers in BST is confirmed by density functional theory (DFT) calculations. Experimental characterization demonstrates the polarization reversal and the existence of domain in BST film. The BST film conductivity is tested as 2.98×10-4 S/cm, which is comparable to the TiO2 being used as the electron transporting layer (ETL) in PSCs. The calculations results prove that BST can be introduced into the PSCs and the interfacial charge transfer can be tuned by ferroelectric polarization. Thus, we fabricated the BST-based PSCs with a champion power conversion efficiency (PCE) of 19.05% after poling, which is higher for 4% than that without poling.

External Chemical Reactivity of Fullerenes and Nanotubes

2001 ◽  
Vol 675 ◽  
Author(s):  
Seongjun Park ◽  
Deepak Srivastava ◽  
Kyeongjae Cho
Keyword(s):  
Density Functional ◽  
Chemical Reactivity ◽  
Density Functional Theory Calculations ◽  
Reaction Energy ◽  
Potential Density ◽  
Functional Theory ◽  
Ab Initio Simulation ◽  
Total Reaction ◽  
Local Bonding ◽  
Pseudo Potential

ABSTRACTThe external chemical reactivity of graphene sheet, fullerenes and carbon nanotubes has been investigated. The total reaction energy is analyzed with several contributing terms and formulated as a function of the pyramidal angles of C atoms. We have determined the parameters for the formulae from ab initio simulation of graphene. We have applied them to predict hydrogenation energy of several nanotubes and C60, and demonstrated that the predicted total reaction energies are very close to the results of total energy pseudo-potential density functional theory calculations. This analysis can be used to predict the reaction energy and local bonding configuration of a reactant with diverse fullerenes and nanotubes within 0.1 eV accuracy.

Synthesis of luminescent cocrystals based on fluoranthene and the analysis of weak interactions and photophysical properties

2021 ◽  
Vol 77 (9) ◽  
Author(s):  
Pengfei Wu ◽  
Long Zhou ◽  
Shuwei Xia ◽  
Liangmin Yu
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Spectroscopic Analysis ◽  
Weak Interactions ◽  
Photophysical Properties ◽  
Luminescent Materials ◽  
Functional Theory ◽  
Fluorescent Materials ◽  
Bonding Density ◽  
Transfer Properties

A series of luminescent cocrystals with fluoranthene (C16H10) as the fluorophore and benzene-1,2,4,5-tetracarbonitrile (TCNB, C10H2N4), 2,3,5,6-tetrafluorobenzene-1,4-dicarbonitrile (TFP, C8F4N2) and 1,2,3,4,5,6,7,8-octafluoronaphthalene (OFN, C10F8) as the coformers was designed and synthesized. Structure analysis revealed that these layered structures were due to charge transfer, π–π interactions and hydrogen bonding. Density functional theory (DFT) calculations show that fluoranthene–TCNB and fluoranthene–TFP have charge-transfer properties, while fluoranthene–OFN does not, indicating that fluoranthene–OFN has arene–perfluoroarene (AP) interactions, which was also demonstrated by spectroscopic analysis, which shows that the photophysical properties of luminescent materials can be tuned by forming cocrystals. These results all prove that utilizing supramolecular cocrystals to develop new fluorescent materials is an effective strategy, which has much potential in optoelectronic applications.

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