Computational Study on Triphenylamine-Based Dyes Containing Benzimidazole Units for Dye-Sensitized Solar Cells

2013 ◽  
Vol 668 ◽  
pp. 110-114
Author(s):  
Zhong Quan Wan ◽  
Lin Lei Zhou ◽  
Chun Yang Jia ◽  
Xiao Jun Yao ◽  
Yu Shi
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
High Efficiency ◽  
Computational Study ◽  
Electronic Absorption Spectra ◽  
Energy Levels ◽  
Dye Sensitized Solar Cells ◽  
Conduction Band Edge ◽  
Tio2 Electrode ◽  
Lowest Unoccupied Molecular Orbital

Three novel dyes (D1, D2 and D3) containing triphenylamine (TPA) unit as core and bearing different benzimidazole units as secondary electron-donors are designed. The geometries, electronic structures, and electronic absorption spectra of these dyes are studied by DFT and TD-DFT. The optimized results indicate that these dyes are all non-coplanar, which can help to inhibit the close intermolecular π-π stacking aggregation effectively. The lowest unoccupied molecular orbital (LUMO) energy levels of the dyes are higher than the conduction band edge of the TiO2, which ensures a high efficiency of electron transfer from these dyes to TiO2 electrode. As the highest occupied molecular orbital (HOMO) energy levels of these dyes are lower than those of I-/I-3, these molecules that lose electrons could be restored by getting electrons from electrolyte. The absorption spectra of these dyes are simulated, and the calculated results indicate that D3 can absorb more photons than those of D1, D2 and TPAR in the region from 250 to 580 nm, which should have the best performance of photo-to-electric conversion efficiency.

scholarly journals Electronic Properties of Triangle Molybdenum Disulfide (MoS2) Clusters with Different Sizes and Edges

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1157
Author(s):  
Songsong Wang ◽  
Changliang Han ◽  
Liuqi Ye ◽  
Guiling Zhang ◽  
Yangyang Hu ◽  
...  
Keyword(s):  
Quantum Chemistry ◽  
Electronic Properties ◽  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electronic Structures ◽  
Edge States ◽  
Frontier Orbitals ◽  
Edge Structure ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The electronic structures and transition properties of three types of triangle MoS2 clusters, A (Mo edge passivated with two S atoms), B (Mo edge passivated with one S atom), and C (S edge) have been explored using quantum chemistry methods. The highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap of B and C is larger than that of A, due to the absence of the dangling of edge S atoms. The frontier orbitals (FMOs) of A can be divided into two categories, edge states from S3p at the edge and hybrid states of Mo4d and S3p covering the whole cluster. Due to edge/corner states appearing in the FMOs of triangle MoS2 clusters, their absorption spectra show unique characteristics along with the edge structure and size.

scholarly journals Emphasizing the Operational Role of a Novel Graphene-Based Ink into High Performance Ternary Organic Solar Cells

2019 ◽  
Author(s):  
Minas M. Stylianakis ◽  
Dimitriοs M. Kosmidis ◽  
Katerina Anagnostou ◽  
Christos Polyzoidis ◽  
Miron Krassas ◽  
...  
Keyword(s):  
Solar Cells ◽  
Molecular Orbital ◽  
Organic Solar Cells ◽  
High Performance ◽  
Energy Levels ◽  
Fullerene Derivative ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital ◽  
Synthetic Routes

A novel solution-processed graphene-based material was synthesized by treating graphene oxide (GO) with 2,5,7-trinitro-9-oxo-fluorenone-4-carboxylic acid (TNF-COOH) moieties, via simple synthetic routes. The yielded molecule N-[(carbamoyl-GO)ethyl]-N’-[(carbamoyl)-(2,5,7-trinitro-9-oxo-fluorene)] (GO-TNF) was thoroughly characterized and it was shown that it presents favorable highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels to function as a bridge component between the polymeric donor poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl}) (PTB7) and the fullerene derivative acceptor [6,6]-phenyl-C71-butyric-acid-methylester (PC71BM). In this context, a GO-TNF based ink was prepared and directly incorporated within the binary photoactive layer, in different volume ratios (1-3% ratio to the blend), for the effective realization of inverted ternary organic solar cells (OSCs) of the structure ITO/PFN/PTB7:GO-TNF:PC71BM/MoO3/Al. The addition of 2% v/v GO-TNF ink led to a champion power conversion efficiency (PCE) of 8.71% that was enhanced by ~13% as compared to the reference cell.

scholarly journals Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

2017 ◽  
Vol 13 ◽  
pp. 863-873 ◽  
Author(s):  
Vinila N Viswanathan ◽  
Arun D Rao ◽  
Upendra K Pandey ◽  
Arul Varman Kesavan ◽  
Praveen C Ramamurthy
Keyword(s):  
Molecular Orbital ◽  
Architectural Design ◽  
Density Functional ◽  
Short Circuit ◽  
Energy Levels ◽  
Photovoltaic Performance ◽  
Hole Mobility ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Lowest Unoccupied Molecular Orbital

A series of low band gap, planar conjugated polymers, P1 (PFDTBT), P2 (PFDTDFBT) and P3 (PFDTTBT), based on fluorene and benzothiadiazole, was synthesized. The effect of fluorine substitution and fused aromatic spacers on the optoelectronic and photovoltaic performance was studied. The polymer, derived from dithienylated benzothiodiazole and fluorene, P1, exhibited a highest occupied molecular orbital (HOMO) energy level at −5.48 eV. Density functional theory (DFT) studies as well as experimental measurements suggested that upon substitution of the acceptor with fluorine, both the HOMO and lowest unoccupied molecular orbital (LUMO) energy levels of the resulting polymer, P2, were lowered, leading to a higher open circuit voltage and short circuit current with an overall improvement of more than 110% for the photovoltaic devices. Moreover, a decrease in the torsion angle between the units was also observed for the fluorinated polymer P2 due to the enhanced electrostatic interaction between the fluorine substituents and sulfur atoms, leading to a high hole mobility. The use of a fused π-bridge in polymer P3 for the enhancement of the planarity as compared to the P1 backbone was also studied. This enhanced planarity led to the highest observed mobility among the reported three polymers as well as to an improvement in the device efficiency by more than 40% for P3.

Electrochemistry, a Useful Tool in the Synthesis of Oligothiophenes

2021 ◽  
Vol 25 ◽  
Author(s):  
Fabiana Pandolfi ◽  
Martina Bortolami ◽  
Marta Feroci ◽  
Leonardo Mattiello ◽  
Vincenzo Scarano ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Organic Semiconductors ◽  
Organic Solar Cells ◽  
Field Effect Transistors ◽  
Energy Levels ◽  
Organic Field Effect Transistors ◽  
Light Emitting ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital ◽  
Organic Photodetectors

: Thiophene derivatives, either "small molecules," oligomers or polymers, play a role of primary importance among organic semiconductors. Therefore they have numerous and different technological applications in the field of Organic Electronics. For this reason, thiophene-based materials are found in devices such as organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), organic solar cells (OSCs), organic photodetectors, and many others. Oligothiophenes and polythiophenes have in common excellent charge transport properties and synthetic procedures that are now well established. Furthermore, oligothiophenes do not possess the intrinsic disadvantages of polythiophenes, such as the lack of well-defined structures and the inevitable presence of impurities. Electrochemistry can give a significant contribution to the field of oligothiophenes not only by allowing the determination of the highest-occupied molecular orbital (HOMO) and the lowest-unoccupied molecular orbital (LUMO) energy levels by the means of cyclic voltammetry (CV), but also rendering oligothiophenes syntheses more expeditious in comparison with the classical organic ones. This review outlines the application of electrochemistry techniques to the synthesis of oligothiophene derivatives.

The electronic absorption spectra of some N-sulfinylanilines. A molecular orbital treatment

1997 ◽  
Vol 75 (7) ◽  
pp. 934-941 ◽  
Author(s):  
R. Abu-Eittah ◽  
H. Moustafa ◽  
A.M. Al-Omar
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electron Acceptor ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Basis Sets ◽  
Theoretical Treatment ◽  
Molecular Orbital Calculations ◽  
Strong Electron ◽  
Anti Conformer

The electronic absorption spectra of N-sulfinylaniline and some of its derivatives were investigated using different solvents. The spectral behavior of the molecules indicated their planarity and that the NSO group is a strong electron acceptor. All the observed bands correspond to delocalized π → π* transitions; n → π* transition were not observed as discrete bands. Ab initio molecular orbital calculations were performed using four different basis sets. The results showed that the NSO group is nonlinear, the molecules studied are planar, and the syn conformer is more stable than the anti conformer. Keywords: N-sulfinylanilines, spectra and theoretical treatment.

Synthesis, crystal structure and photophysical properties of 1,4-bis(1,3-diazaazulen-2-yl)benzene: a new π building block

2018 ◽  
Vol 74 (2) ◽  
pp. 171-176
Author(s):  
Peili Sun ◽  
Zongyao Zhang ◽  
Hongxia Luo ◽  
Pu Zhang ◽  
Yujun Qin ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Building Block ◽  
Photophysical Properties ◽  
Condensation Reaction ◽  
Energy Levels ◽  
Three Dimensional ◽  
Experimental Result ◽  
Monoclinic System ◽  
H Nmr ◽  
Lowest Unoccupied Molecular Orbital

A dimerized 1,3-diazaazulene derivative, namely 1,4-bis(1,3-diazaazulen-2-yl)benzene [or 2,2′-(1,4-phenylene)bis(1,3-diazaazulene)], C22H14N4, (I), has been synthesized successfully through the condensation reaction between 2-methoxytropone and benzene-1,4-dicarboximidamide hydrochloride, and was characterized by 1H NMR and 13C NMR spectroscopies, and ESI–MS. X-ray diffraction analysis reveals that (I) has a nearly planar structure with good π-electron delocalization, indicating that it might serve as a π building block. The crystal belongs to the monoclinic system. One-dimensional chains were formed along the a axis through π–π interactions and adjacent chains are stabilized by C—H...N interactions, forming a three-dimensional architecture. The solid emission of (I) in the crystalline form exhibited a 170 nm red shift compared with that in the solution state. The observed optical bandgap for (I) is 3.22 eV and a cyclic voltammetry experiment confirmed the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The calculated bandgap for (I) is 3.37 eV, which is very close to the experimental result. In addition, the polarizability and hyperpolarizability of (I) were appraised for its further application in second-order nonlinear optical materials.

EXCITED-STATE INTRAMOLECULAR ELECTRON TRANSFER COUPLED WITH EXCITED-STATE INTRAMOLECULAR PROTON TRANSFER IN PHOTOINDUCED ENOL TO KETO TAUTOMERIZATION

2009 ◽  
Vol 08 (supp01) ◽  
pp. 1073-1086
Author(s):  
YUANZUO LI ◽  
SHASHA LIU ◽  
LILI ZHAO ◽  
MAODU CHEN ◽  
FENGCAI MA ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Charge Transfer ◽  
Proton Transfer ◽  
Molecular Orbital ◽  
Energy Levels ◽  
Three Dimensional ◽  
Intramolecular Proton Transfer ◽  
Intramolecular Electron Transfer ◽  
Lowest Unoccupied Molecular Orbital

In this paper, the two-dimensional (2D) site and the three-dimensional (3D) cube representations [Sun MT, J Chem Phys124: 054903, 2006] have been further developed to study the charge transfer during excited-state relaxation. With these newly developed representations, we theoretically investigate the excited-state intramolecular electron transfer (ESIET) in enol excited-state geometry relaxation, and ESIET coupled with excited-state intramolecular proton transfer (ESIPT) in phototautomerization (in enol to keto transformation). The energy levels of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of HBODC in enol and keto absorption and fluorescence are compared to understand photoinduced ESIET and ESIPT process. The excited regions of molecule (where arrangement of electron density takes place during excited-state relaxation) are located with 2D site representation. 3D cube representations visualize the character of charge transfer (CT) in those regions. Results of the research indicate that the ability of charge transfer during enol excited-state geometry relaxation is much stronger than that in phototautomerization.

scholarly journals Density Functional Theory Study on the Electronic Structures of Oxadiazole Based Dyes as Photosensitizer for Dye Sensitized Solar Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Umer Mehmood ◽  
Ibnelwaleed A. Hussein ◽  
Khalil Harrabi ◽  
Shakeel Ahmed
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectra ◽  
Density Functional ◽  
Energy Levels ◽  
Dye Sensitized Solar Cells ◽  
Electron Injection ◽  
Molecular Structures ◽  
Visible Absorption ◽  
Functional Theory ◽  
Oxidation Potentials

The molecular structures and UV-visible absorption spectra of complex photosensitizers comprising oxadiazole isomers as theπ-bridges were analyzed by density functional theory (DFT) and time-dependent DFT. The ground state and excited state oxidation potentials, HOMOs and LUMOs energy levels, and electron injection from the dyes to semiconductor TiO2have been computed in vacuum here. The results show that all of the dyes may potentially be good photosensitizers in DSSC. To justify the simulation basis, N3 dye was also simulated under the similar conditions. Simulated absorption spectrum, HOMO, LUMO, and band gap values of N3 were compared with the experimental values. We also computed the electronic structure properties and absorption spectra of dye/(TiO2)8systems to elucidate the electron injection efficiency at the interface. This work is expected to give proper orientation for experimental synthesis.

The Electronic Absorption Spectra of Some N-Substituted Pyrroles—Molecular Orbital Calculations

1982 ◽  
Vol 36 (3) ◽  
pp. 297-301 ◽  
Author(s):  
R. Abu-Eittah ◽  
R. Hilal ◽  
M. S. El-Shall
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electronic Absorption ◽  
Electronic Transition ◽  
Electronic Absorption Spectra ◽  
Experimental Results ◽  
Electronic Transitions ◽  
Molecular Orbital Calculations ◽  
Nonpolar Solvents ◽  
State Functions

The electronic absorption spectra of N-phenylpyrrole and some of its parasubstituted derivatives have been investigated in polar and nonpolar solvents. Such an investigation could predict the extent of resonance interaction between the pyrryl and phenyl moieties of the composite molecule. The direction and polarization of the electronic transitions were predicted. Molecular orbital calculations using the SCF-CI procedures were performed on N-phenylpyrrole and some of its p-substituted derivatives. The state functions and energies were computed. The weight of each configuration was evidence for the direction of the electronic transition. The correspondence between the theoretical and experimental results is satisfactory.

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