Charge Transfer Parameters, Correlative Perturbation Potential with Non‐Linear Optical Properties of Bi‐Heterocyclic Dyes Having TCF Acceptor‐ DFT Approach

Ghanavatkar, Chaitannya W.; Mishra, Virendra; Sekar, Nagaiyan

doi:10.1002/slct.202003145

Cited by 7 publications

(7 citation statements)

References 78 publications

(168 reference statements)

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“…The positive and zero BLA value corresponds to the cyanine and neutral state of the system, respectively, whereas the negative value is significant for the zwitterionic (charge‐separated state) form of the system [78] . Since BLA mainly depends on ICT property, they can also interpret the NLO properties [78–80] …”

Section: Resultsmentioning

confidence: 99%

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Charge Transfer as Bridging Correlator for DSSC Efficiency and NLO Property

Sharma

Sekar

2022

ChemistrySelect

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The efficacy of dipyridyl and diphenylamine sensitizers in dyesensitized solar cells (DSSCs) is linked to trends in DFT-based charge transfer and non-linear optical (NLO) properties. We chose DFT and Time-dependent-DFT methods. The planarity is improved by replacing the phenyl ring at the donor site with a thiophene ring. Similarly, cyanoacetic acid acceptor improves planarity over rhodamine-3-acetic acid acceptor. In all cases in HOMO, the electron density is located at the donor and some part of the spacer, and in LUMO, it is shifted to the acceptor. Bond length alternation, bond order alternation, quinoid character, effective charge transferred distance, effective charge transferred, chemical potential, electrophilicity index, and electron correlation descriptors showed direct relation, while hardness and hyperhardness showed an inverse relation with NLO properties. We observed higher β 0 and γ for thiophenebased sensitizers ranging from 248.81 × 10 À 30 to 440.92 × 10 À 30 esu and 777.82 × 10 À 36 to 1442.69 × 10 À 36 esu, respectively. Likewise, more negative values of ΔGinject (À 0.630 to À 0.752 eV), a smaller value of ΔGreg (0.662 to 0.790 eV), and higher LHE (0.959 to 0.976) are observed for thiophene-based sensitizers. Also, thiophene-based sensitizers showed shorter TiÀ O bond lengths than their phenyl-based sensitizers. Photovoltaic parameters are directly related to DSSC efficiency and NLO properties.

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Section: Resultsmentioning

confidence: 99%

“…[78] Since BLA mainly depends on ICT property, they can also interpret the NLO properties. [78][79][80] The conjugated segments of sensitizers used for S1 to S8 are shown in SI Figure 7. The BLA and BOA properties of sensitizers S1 to S8 in gas and DMF are tabulated in Tables 7 and 8.…”

Section: Bond Length Alternation (Bla) and Bond Order Alternation (Boa)mentioning

confidence: 99%

Charge Transfer as Bridging Correlator for DSSC Efficiency and NLO Property

Sharma

Sekar

2022

ChemistrySelect

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“…The resistance of the system to this change can be measured as the hardness,

η

, which is the second derivative of energy with respect to the number of electrons and can be given by Equation [71, 72] ():

η = \frac{\partial μ}{\partial N} = \frac{\partial^{2} E}{\partial N^{2}} = (\frac{E_{HOMO -} E_{LUMO}}{2})

The hardness and chemical potential together account for the electrophilic power of a system defined as the electrophilicity index, ω given as [72, 73]:

ω = \frac{μ^{2}}{η}

The further resistance to the change in hardness of the system with change in number of electrons can be calculated as the hyperhardness, Γ . It is the third derivative of energy with respect to number of electrons and is expressed as [74, 75]:

Γ = \frac{\partial η}{\partial N} = \frac{\partial^{2} μ}{\partial N^{2}} = \frac{\partial^{3} E}{\partial N^{3}}

For the benzothiadiazole‐based sensitizers E and F, the electrophilicity index derived from the DFT calculations is shown to be higher, although an opposite trend was reported for chemical potential, hardness, and hyperhardness (Table S3). The introduction of EDOT bridge in sensitizer F leads to lowering in the electrophilicity index compared to sensitizer E. A similar effect can be seen when G and H are compared.…”

Section: Resultsmentioning

confidence: 99%

“…The further resistance to the change in hardness of the system with change in number of electrons can be calculated as the hyperhardness, Γ. It is the third derivative of energy with respect to number of electrons and is expressed as [74,75]:…”

Section: Reactivity Of the Sensitizersmentioning

confidence: 99%

Effect of bridged spacers and auxiliary acceptors on Dye Sensitized Solar Cell sensitizers: A density functional theory‐based investigation

Shukla

Sharma

Sekar

2022

Int J of Quantum Chemistry

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Four donor‐pi‐acceptor (D‐π‐A) type sensitizers containing coumarin as the donor unit and cyanoacrylic acid as the acceptor unit are investigated using density functional theory (DFT) and time‐dependent‐DFT methods. The effect of introducing auxiliary acceptor like benzothiadiazole and spacer bridge like 3,4‐ethylenedioxythiophene (EDOT) is analyzed. The EDOT bridge leads to increase in band gap whereas the introduction of benzothiadiazole lessens the band gap. The frontier molecular orbital diagram also shows an efficient intramolecular charge transfer for non‐EDOT based sensitizers. For benzothiadiazole‐based sensitizers, the electrophilicity index was higher and hyperhardness was lower in the estimated reactivity descriptors. The experimentally determined light harvesting efficiency (LHE) of the sensitizers is correlated with the calculated global descriptors. A direct relation of LHE is obtained with electrophilicity index and an inverse relation for hyperhardness. A reverse trend is seen on comparing these descriptors with the band gap of the sensitizers. The computed non‐linear optical (NLO) characteristics show that the benzothiadiazole acceptor increases NLO response, while EDOT‐based sensitizers show a reduced NLO response. The NLO properties also give a direct relation with the LHE and electrophilicity index. The hyperpolarizability exhibits an inverse relation with the transition energy which is in accordance with the Ouder's model.

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“…[71][72][73][74][75][76] Hyperhardness, the third derivative of energy with respect to number of electrons, is directly dependent on hardness. [77,78] The reverse trend in hyperhardness is due to decrease in the hardness of the sensitizers after attaching to the TiO 2 core.…”

Section: Homo-lumomentioning

confidence: 99%

Effect of 3,4‐ethylenedioxythiophene (EDOT) as Bridged Spacer on DSSC and Non Linear Optical (NLO) Properties: A DFT Approach

Kumari Shukla,

Sekar

2024

ChemistrySelect

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Density functional theory (DFT) and time dependent DFT (TD‐DFT) techniques are used to explore six donor‐pi‐acceptor (D−A) type sensitizers that comprise coumarin as the donor unit and cyanoacrylic acid as the acceptor unit. It is examined how adding a spacer bridge like 3,4‐ethylenedioxythiophene (EDOT) affects the system. The introduction of EDOT leads to destabilization of highest occupied molecular orbital (HOMO) in both bare and TiO2 anchored sensitizers. The frontier molecular orbital (FMO) also depicts an effective intramolecular charge transfer from the EDOT unit to the acceptor unit in bare sensitizers and to the TiO2 core in TiO2 anchored sensitizers respectively. The FMO diagram of TiO2 anchored non‐bridged sensitizers reveals an electron‐deficient sensitizer unit coupled to an electron‐rich TiO2 core resulting in a poor charge transfer. The calculated Voc values are also found to be more for EDOT based sensitizers and hence making the EDOT bridged sensitizers efficient for DSSC application. According to the TD‐DFT investigation, the EDOT bridging sensitizers exhibit red‐shifted vertical excitation when compared to the corresponding non bridged sensitizers, which is consistent with the experimental data reported previously.

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Charge Transfer Parameters, Correlative Perturbation Potential with Non‐Linear Optical Properties of Bi‐Heterocyclic Dyes Having TCF Acceptor‐ DFT Approach

Cited by 7 publications

References 78 publications

Charge Transfer as Bridging Correlator for DSSC Efficiency and NLO Property

Charge Transfer as Bridging Correlator for DSSC Efficiency and NLO Property

Effect of bridged spacers and auxiliary acceptors on Dye Sensitized Solar Cell sensitizers: A density functional theory‐based investigation

Effect of 3,4‐ethylenedioxythiophene (EDOT) as Bridged Spacer on DSSC and Non Linear Optical (NLO) Properties: A DFT Approach

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