scholarly journals Structural modulation of π-conjugated linkers in D–π–A dyes based on triphenylamine dicyanovinylene framework to explore the NLO properties

2021 ◽  
Vol 8 (8) ◽  
pp. 210570
Author(s):  
Muhammad Khalid ◽  
Muhammad Usman Khan ◽  
Iqra Shafiq ◽  
Riaz Hussain ◽  
Akbar Ali ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Optical Materials ◽  
Density Functional ◽  
Visible Region ◽  
Functional Theory ◽  
Nlo Properties ◽  
Structural Modifications ◽  
Nlo Response ◽  
Nlo Materials ◽  
Structural Modulation

A donor–π–acceptor type series of Triphenylamine–dicyanovinylene-based chromophores ( DPMN1–DPMN11 ) was designed theoretically by the structural tailoring of π-linkers of experimentally synthesized molecules DTTh and DTTz to exploit changes in the optical properties and their nonlinear optical materials (NLO) behaviour. Density functional theory (DFT) computations were employed to understand the electronic structures, absorption spectra, charge transfer phenomena and the influence of these structural modifications on NLO properties. Interestingly, all investigated chromophores exhibited lower band gap (2.22–2.60 eV) with broad absorption spectra in the visible region, reflecting the remarkable NLO response. Furthermore, natural bond orbital (NBO) findings revealed a strong push–pull mechanism in DPMN1–DPMN11 as donor and π-conjugates exhibited positive, while all acceptors showed negative values. Examination of electronic transitions from donor to acceptor moieties via π-conjugated linkers revealed greater linear (〈 α 〉 = 526.536–641.756 a.u.) and nonlinear ( β tot = 51 313.8–314 412.661 a.u.) response. It was noted that the chromophores containing imidazole in the second p-linker expressed greater hyperpolarizability when compared with the ones containing pyrrole. This study reveals that by controlling the type of π-spacers, interesting metal-free NLO materials can be designed, which can be valuable for the hi-tech NLO applications.

scholarly journals Density Functional Theory Predictions of the Nonlinear Optical (NLO) Properties in Triphenylamine based α-Cyanocinnamic Acid Compounds: Effect of Fluorine on NLO Response

2019 ◽  
Vol 62 (3) ◽  
Author(s):  
Muhammad Ramzan Saeed Ashraf Janjua Janjua
Keyword(s):  
Phenyl Ring ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Second Order ◽  
Functional Theory ◽  
Nlo Properties ◽  
Nlo Response ◽  
Nlo Materials ◽  
Cyanocinnamic Acid ◽  
Insight Into

In this study, the energy gaps, second-order nonlinear optical (NLO) properties and dipole polarizabilities of triphenylamine based α-cyanocinnamic acid acetylene derivatives have been investigated via using time-dependent density functional response theory. These compounds were designed theoretically by fluorine (F) atom substitution at different positions of phenyl ring end of the α-cyanocinnamic acid segment. The results have indicated that the systems substituted by fluorine show remarkable NLO second-order response, especially D4 system with computed static second-order polarizability (βtot) of 70537.95 (a.u). Hence, these materials have the likelihood to be an excellent second-order nonlinear optical (NLO) materials. The βtot value suggests that along the x-axis the charge transfer (CT) from triphenylamine to α-cyanocinnamic acid (D-A) plays a key role in NLO response; whereas α-cyanocinnamic acid acts as an acceptor (A) and triphenylamine acts as a donor (D) in all the studied systems. Incorporation of an electron acceptor (F) at the phenyl ring end of the α-cyanocinnamic acid segment increases the computed βtot values. The present investigation therefore provides an important insight into the remarkably greater NLO properties of α-cyanocinnamic acid and triphenylamine attached via acetylene.

First Principle Study of Electronic and Non-Linear Optical (NLO) Properties of Triphenylamine Dyes: Interactive Design Computation of New NLO Compounds

2016 ◽  
Vol 69 (4) ◽  
pp. 467 ◽  
Author(s):  
Muhammad Ramzan Saeed Ashraf Janjua ◽  
Zain Hassan Yamani ◽  
Saba Jamil ◽  
Asif Mahmood ◽  
Imran Ahmad ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectra ◽  
Density Functional ◽  
Conjugation Length ◽  
Functional Theory ◽  
Nlo Properties ◽  
Non Linear ◽  
Design Computation ◽  
Notable Increase ◽  
Linear Optical

In this study, density functional theory and time-dependent density functional theory are used to determine how the size of π-conjugated system influences the absorption spectra and non-linear optical (NLO) properties of dyes. Double and triple bonds, as well the benzene rings, are used in conjugated systems. The results of the theoretical computation show that the absorption spectra are gradually broadened and red-shifted with increases in the conjugation length. Theoretical examination of the NLO properties was performed on the key parameters of polarizability and hyperpolarizability. A notable increase in the non-linear optical response was observed with an increase in the conjugation length of the π-spacer.

Structures and Absorption Spectrum of 1D and 2D ZnS Nanoparticles

2020 ◽  
Vol 5 (1) ◽  
pp. 26-35
Author(s):  
Spyros Papantzikos ◽  
Alexandos G. Chronis ◽  
Fotios I. Michos ◽  
Mihail M. Sigalas
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Toxic Elements ◽  
Visible Region ◽  
Visible Spectrum ◽  
Zns Nanoparticles ◽  
Major Drawback ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Optimized Geometries

Background: ZnS nanoparticles (NPs) are attractive for quantum dots applications because they consist of abundant and non-toxic elements. Their major drawback is that they absorb in the UV region, ultimately limiting their applications. Objective: In the present study, 1D and 2D ZnS NPs have been found. The goal of this study is to find NPs that have absorption in the visible spectrum. Methods: Calculations based on the Density Functional Theory (DFT) have been used to find the optimized geometries. Their absorption spectra have been calculated with the Time-Dependent DFT. Results: Several shapes were examined, such as nanorod, and it is observed that these shapes move the absorption spectra in lower energies, into the visible spectrum, while the 3D NPs have absorption edges in the UV region. Conclusion: NPs with the shape of nanorod in different directions showed that their absorption spectra moved to lower energies well inside the visible spectrum with significantly high oscillator strength. In contrast with the mostly used CdSe NPs, the ZnS NPs are made from more abundant and less toxic elements. Therefore, by making them absorb in the visible region, they may find significant applications in solar cells and other photonic applications.

Tuning Second-Order Non-linear (NLO) Optical Response of Organoimido-Substituted Hexamolybdates through Halogens: Quantum Design of Novel Organic-Inorganic Hybrid NLO Materials

2010 ◽  
Vol 63 (5) ◽  
pp. 836 ◽  
Author(s):  
Muhammad Ramzan Saeed Ashraf Janjua ◽  
Zhong-Min Su ◽  
Wei Guan ◽  
Chun-Guang Liu ◽  
Li-Kai Yan ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Phenyl Ring ◽  
Density Functional ◽  
Organic Ligand ◽  
Second Order ◽  
Inorganic Hybrid ◽  
Nlo Properties ◽  
Nlo Response ◽  
Non Linear ◽  
Nlo Materials

The second-order non-linear optical (NLO) response of organoimido-substituted hexamolybdates has been tuned from 218.61 × 10–30 to 490.10 × 10–30 esu. The dipole polarizabilities and second-order nonlinear optical (NLO) properties of organoimido derivatives of hexamolybdates have been investigated by using the time-dependent density functional response theory (TDDFT). The electron withdrawing ability of F (fluorine) has played an important role in tuning the second-order NLO response in this class of organic-inorganic hybrid compounds; particularly system 6 [Mo6O18(NC16H8F2(CF3)2I)]2– with the static second-order polarizability (βvec ) computed to be 490.10 × 10–30 esu. Thus, our studied systems have the feasibility to be excellent tuneable second-order NLO materials. The analysis of the major contributions to the βvec value suggests that the charge transfer (CT) from POM to organic ligand (D-A) along the z-axis has been enhanced with addition of F atoms at the end phenyl ring which directs head (POM) to tail (fluorinated ring) charge transfer. The computed βvec values have been tuned by incorporation of different halogen atoms at the end phenyl ring of organoimido segment. Furthermore, substitution of two trifluoromethyl (–CF3) groups sideways along with iodine (I) at the terminus of end phenyl ring in the organoimido ligand has a striking influence on tuning the optical non-linearity, as CT from POM to the organoimido ligand was significantly increased. These systematic small changes in molecular composition by substitution of different halogen groups leads to a tuning the NLO response; the so-called ‘ripple effect’ catches this point nicely. Thus, the present investigation provides thought provoking insight into the tuneable NLO properties of organoimido-substituted hexamolybdates.

Solvent-Dependent Non-Linear Optical Properties of 5,5′-Disubstituted-2,2′-bipyridine Complexes of Ruthenium(II): A Quantum Chemical Perspective

2015 ◽  
Vol 68 (10) ◽  
pp. 1502 ◽  
Author(s):  
Muhammad Ramzan Saeed Ashraf Janjua ◽  
Saba Jamil ◽  
Asif Mahmood ◽  
Atifa Zafar ◽  
Muhammad Haroon ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Solvent Polarity ◽  
Functional Theory ◽  
Nlo Properties ◽  
Structural Modifications ◽  
Wide Range ◽  
Non Linear ◽  
Linear Optical Properties ◽  
Linear Optical

In this research article, we reported solvent effects on non-linear optical (NLO) properties of 5,5′-disubstituted-2,2′-bipyridine complexes of ruthenium. The polarizability (α) and hyperpolarizability (β) were calculated in the gas phase. Benzene (ϵ (dielectric constant) = 2.3), THF (ϵ = 7.52), dichloromethane (ϵ = 8.93), acetone (ϵ = 21.01), methanol (ϵ = 33.00), and water (ϵ = 80.10) were used by density functional theory. These solvents cover a wide range of polarities. The results of theoretical investigation showed that the non-linear optical properties were significantly increased with the increase in solvent polarity. The results of this study also showed that similarly to structural modifications, polarity of the medium may play a significant role in modulating the NLO properties.

Regulating the NLO response of anthraquinone-supported thiourea-linked crown ether macrocycle by introducing metal cations: A DFT study

2020 ◽  
Vol 19 (05) ◽  
pp. 2050017
Author(s):  
Yao Yao ◽  
Jin-Ting Ye ◽  
Xiang Li ◽  
Yuan Zhang ◽  
Si-Nan Zhu ◽  
...  
Keyword(s):  
Density Functional ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Metal Cations ◽  
Alkaline Earth Metal ◽  
Functional Theory ◽  
Nlo Properties ◽  
Thiourea Group ◽  
Nlo Materials ◽  
The Subject

Recently, an anthraquinone-supported thiourea group linking a 1-aza-18-crown-6 macrocycle L has been the subject of extensive attention due to the perfect affinity towards metal cations. This work systematically researched the effects of different metal cations ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]) on the second-order nonlinear optical (NLO) properties of macrocycle L by density functional theory (DFT). DFT calculations revealed that the values of first hyperpolarizabilities ([Formula: see text] decrease significantly when alkaline earth metal cations ([Formula: see text] and [Formula: see text]) were injected into macrocycle L due to the smaller charge transfer (CT) transition and larger transition energy. Conversely, the variations of [Formula: see text] values in alkali metal cations ([Formula: see text] and [Formula: see text] and transition metal cations ([Formula: see text] and [Formula: see text]) derivatives are not obvious compared to the [Formula: see text] value of macrocycle L. Therefore, the NLO properties of macrocycle can be effectively regulated by alkaline earth metal cations. Furthermore, we found that the [Formula: see text] value of anion-controlled complex Na(L)(ClO4) is larger than that of L*Na+ complex because the anion [Formula: see text] improves the planarity of anthraquinone-supported thiourea group leading to the enhancement of the CT ability. In addition, the influence of frequency-dependent on the first hyperpolarizabilities is weak for the current systems. Hence, we look forward to the conception of this work will offer a fundamental guideline and reference for further research for novel NLO materials.

Theoretical exploration to the cation effect on the second-order nonlinear optical properties of Strandberg-type polyoxometalates

2015 ◽  
Vol 14 (01) ◽  
pp. 1550007 ◽  
Author(s):  
Ting Zhang ◽  
Wei Guan ◽  
Shizheng Wen ◽  
Tengying Ma ◽  
Likai Yan ◽  
...  
Keyword(s):  
Density Functional ◽  
Nonlinear Optical ◽  
Dft Method ◽  
Transition Metal Ions ◽  
Second Order ◽  
Functional Theory ◽  
Cation Effect ◽  
Nlo Response ◽  
Polar Materials ◽  
Nlo Materials

The combination of cations with octahedral coordinated d0 transition metal ions has been proved to be an effective way for designing new polar materials. So we investigate the second-order nonlinear optical (NLO) properties of Strandberg-type polyoxometalates (POMs) with alkali metal cations M 6 Mo 5 X 2 O 23 ( M = K +, Rb +, Cs +; X = P , As ) and M 4 M o5 X 2 O 21 ( M = K +, Rb +, Cs +; X = S , Se , Te ) by density functional theory (DFT) method. The calculated results show that this kind of Strandberg-type POMs possesses remarkably large molecular second-order NLO polarizability, especially for the Cs 6 Mo 5 P 2 O 23 (system Ic), which has a computed β0 value of 12526 a.u. and might be an excellent second-order NLO material. Moreover, the cations have important impact on the second-order NLO polarizabilities. Therefore, a careful choice of appropriate cations may allow the control of the second-order NLO response on these Strandberg-type POMs, which may provide a new route to design efficient NLO materials.

A Theoretical Investigation on Second-Order NLO Properties of Organic Substitutions of [Mo6O19]2- and [MoW5O19]2-

2019 ◽  
Vol 960 ◽  
pp. 268-273
Author(s):  
Qi Li ◽  
Xiu Hua Yuan
Keyword(s):  
Molecular Structure ◽  
High Performance ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Second Order ◽  
Functional Theory ◽  
Nlo Properties ◽  
Potential Applications ◽  
Nlo Materials ◽  
Different Parts

In this study, density functional theory (DFT) was used to calculate second-order polarizabilities and second-order polarizabilities densities of a series of organic substitution for Lindqvist-type polyoxometalates (POMs), and the nonlinear optical (NLO) properties was also analyzed. We found that βzzz has the main contribution to β value. The expansion of molecular structure on z-axis greatly increased second-order polarizabilities. Both the size of the organic segments and metal hybridization exert an influence on β value. The analysis on the second-order polarizabilities density is used to explain the NLO phenomenon. In the present investigation, metal hybridization and π-conjugation changed the contribution of βzzz value from different parts. The results of this work will contribute to the potential applications in high-performance NLO materials.

scholarly journals Tuning the optoelectronic properties of hematite with rhodium doping for photoelectrochemical water splitting using density functional theory approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdur Rauf ◽  
Muhammad Adil ◽  
Shabeer Ahmad Mian ◽  
Gul Rahman ◽  
Ejaz Ahmed ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Optical Absorption ◽  
Water Splitting ◽  
Density Functional ◽  
Formation Energy ◽  
Visible Region ◽  
Photoelectrochemical Water Splitting ◽  
Theory Approach ◽  
Functional Theory

AbstractHematite (Fe2O3) is one of the best candidates for photoelectrochemical water splitting due to its abundance and suitable bandgap. However, its efficiency is mostly impeded due to the intrinsically low conductivity and poor light absorption. In this study, we targeted this intrinsic behavior to investigate the thermodynamic stability, photoconductivity and optical properties of rhodium doped hematite using density functional theory. The calculated formation energy of pristine and rhodium doped hematite was − 4.47 eV and − 5.34 eV respectively, suggesting that the doped material is thermodynamically more stable. The DFT results established that the bandgap of doped hematite narrowed down to the lower edge (1.61 eV) in the visible region which enhanced the optical absorption and photoconductivity of the material. Moreover, doped hematite has the ability to absorb a broad spectrum (250–800) nm. The enhanced optical absorption boosted the photocurrent and incident photon to current efficiency. The calculated results also showed that the incorporation of rhodium in hematite induced a redshift in optical properties.

scholarly journals Unraveling the electrochemical and spectroscopic properties of neutral and negatively charged perylene tetraethylesters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christian Wiebeler ◽  
Joachim Vollbrecht ◽  
Adam Neuba ◽  
Heinz-Siegfried Kitzerow ◽  
Stefan Schumacher
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Energy Levels ◽  
Spectroscopic Properties ◽  
Absorption Bands ◽  
Functional Theory ◽  
Vertical Excitation ◽  
Hartree Fock ◽  
Tauc Plot ◽  
Electrochemical Approach

AbstractA detailed investigation of the energy levels of perylene-3,4,9,10-tetracarboxylic tetraethylester as a representative compound for the whole family of perylene esters was performed. It was revealed via electrochemical measurements that one oxidation and two reductions take place. The bandgaps determined via the electrochemical approach are in good agreement with the optical bandgap obtained from the absorption spectra via a Tauc plot. In addition, absorption spectra in dependence of the electrochemical potential were the basis for extensive quantum-chemical calculations of the neutral, monoanionic, and dianionic molecules. For this purpose, calculations based on density functional theory were compared with post-Hartree–Fock methods and the CAM-B3LYP functional proved to be the most reliable choice for the calculation of absorption spectra. Furthermore, spectral features found experimentally could be reproduced with vibronic calculations and allowed to understand their origins. In particular, the two lowest energy absorption bands of the anion are not caused by absorption of two distinct electronic states, which might have been expected from vertical excitation calculations, but both states exhibit a strong vibronic progression resulting in contributions to both bands.

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