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A DFT/TD-DFT Study of the Influence of Anchoring Group and Internal Acceptor of Benzocarbazole-based D-A´-π-A Dyes for DSSCs

Received: 3 December 2023     Accepted: 15 January 2024     Published: 29 April 2024
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Abstract

Great attention is being shifted to Dye-sensitized solar cells because of their structural and electronic tunability, high performance, and low cost compared to conservative photovoltaic devices. In this work, the DFT/B3LYP/6-31G(d,p) and TD-DFT/mPW9PW91/6-31G(d,p) levels of theory are applied to the theoretical study of a new class of benzocarbazole-based D-A´-π-A dyes for their potential use in DSSCs. The influence of the internal acceptor on the optoelectronic properties is studied for the dyes. The optoelectronic and photovoltaic properties as HOMO, LUMO, Egap maximum absorption wavelength (λmax), vertical excitation energies (Eex), oscillator strength (f), light harvesting efficiency (LHE), open circuit voltage (Voc), injection force (ΔGinject), were evaluated and discussed in order to compare their performance as DSSC sensitizers. The theoretical results show that all dyes exhibit excellent optoelectronic properties, such as a lower Egap(1.733 eV to 2.173 eV), a significant λmax(631.48 nm to 754.40 nm), a sufficient value of Voc (0.461 V to 0.880 V) and high LHE (0.853 eV to 0.968 eV). In particular M4 with 2,5-dihydropyrrolo [3,4-c]pyrrole-1,4-dithione as auxiliary acceptor has the potential to be used as a sensitizer for DSSCs, due to its red-shifted absorption spectrum (λmax= 754.40 nm), and small energy gap (Egap=1.733 eV). Indeed, this study may help chemists to synthesize efficient dyes for DSSC.

Published in International Journal of Computational and Theoretical Chemistry (Volume 12, Issue 1)
DOI 10.11648/j.ijctc.20241201.11
Page(s) 1-9
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2024. Published by Science Publishing Group

Keywords

Benzocarabzole, DFT/TD-DFT, Auxiliary Acceptor, Photovoltaic Properties, Dye-sensitized Solar Cells

1. Introduction
Currently, solar energy is recognized as the most plentiful among renewable sources, offering significant potential in mitigating challenges stemming from fossil fuels and other environmentally troublesome energy sources . As the third generation solar cells, dye-sensitized solar cells (DSSCs) developed by O'Regan and Gratzel in 1991, have attracted considerable attention in both academia and commercial industry due to their safe fabrication mechanism and ideal PCE . One of the key design parameters of DSSCs is the dye sensitizer, which plays a critical role in photo-electric conversion processes with the functions of light harvesting, electron injection, electrons collection and dye regeneration . So far, sensitizers are divided into two sub-groups: metal-based dyes and metal-free organic dyes . Previously, metal-based dyes (Ru and Zn) were widely used due to their high power conversion efficiency (PCE) . Nevertheless, these metal-based dyes are having an adverse effect on the environment and complex purification processes lead to their limited applications in DSSCs . To address this issue, scientists and researchers are directing their attention toward metal-free organic dyes because of their minimal toxicity, high molar extinction coefficient, ease of accessibility, lightweight properties, and cost-effectiveness. . The reported PCE for these metal-free organic dyes reached up to 14% having a donor-π-acceptor (D-π-A) structure anchored on the surface TiO2 . Among these metal-free sensitizers, carbazole and its derivatives, with advantages of strong emission and adsorption properties, good hole transport capacities and reasonable band gaps , have been proved to be promising candidates for DSSCs efficiency. In this context, several studies have shown that PCEs of carbazole sensitizing dyes can reach 9.20% . Conversely, the efficiency of Dye-Sensitized Solar Cells (DSSCs) is significantly influenced by the molecular structure of the dye. In recent developments, the creation of novel organic dyes adopting the D-A-π-A configuration involves incorporating an internal acceptor into conventional D-π-A dyes . The Studies on D-A-π-A dyes show that the additional internal electron-withdrawing acceptor can be considered as an electron trap having unique characteristics . Insertion of an electron-withdrawing internal group in the D-π-A arrangement not only tunes the absorption energies and energy levels, but also improves the photostability of the sensitizers . Moreover, in DSSCs, the sensitizers directly interact with a mesoporous oxide layer made of nanometre-sized particles (usually TiO2-anatase) through anchoring groups. Therefore, the search for different anchoring groups with the excellent binding ability to the semiconductor is essential to replace conventional carboxylic acid-based anchoring groups such as cyanoacrylic acid because this last is prone to photodegradation during device operation as they dissociate from semiconductor’s surface . Based on the theoretical researches of slimi et al. and G. Deogratias et al. , results showed that 2-(1,1-dicyanomethylene) rhodanine unit is a very promising anchoring group for improving photovoltaic properties of dye sensitizers.
Figure 1. (a) Molecular structure of studied dyes; and (b) their optimized geometry with DFT at the B3LYP/6-31G(d,p) level.
In this work, with the goal to evaluate the effect of internal acceptors on the performance of benzocarbazole dyes, a serious of D-A'-π-A dyes are designed on the basis of LY-8 (R) dye , where D: benzocarbazole, A': benzothiadiazole (M1), 2-methylbenzotriazole (M2), 2,5-dihydropyrrolo [3,4-c] pyrrole-1,4-dione (M3) and 2,5-dihydropyrrolo [3,4-c] pyrrole-1,4-dithione (M4), π-bridge: thiophene, A: 2-(1,1- dicyanomethylene) rhodanine acid (Figure 1a). Theoretical insights into the inherent characteristics of the formulated dyes are provided through density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. This encompasses analyses of molecular geometry, electronic structure, frontier molecular orbitals, absorption spectrum, light harvesting efficiency (LHE), and properties related to photo-induced electron transfer. The objective of this study is to elucidate the impact of internal acceptor types on the photoelectric performance of the dyes. The derived conclusions aim to offer valuable insights for the design and screening of innovative high-performance benzocarbazole dyes for Dye-Sensitized Solar Cells (DSSCs).
2. Computational Details
In this study, all computational calculations were conducted using the Gaussian 09 package . Ground state geometry optimization of the dyes was performed through Density Functional Theory (DFT) calculations, employing the hybrid functional B3LYP and the 6-31G (d,p) basis set , in the gas phase. Additionally, frequency calculations were executed to verify that the optimized structure represented the minimum energy configuration. For the computation of absorption spectra, Time-Dependent Density Functional Theory (TD-DFT) calculations were carried out with the mPW9PW91 functional and a 6-31G(d,p) basis set, utilizing the optimized ground state geometries for the first excited singlet state. Solvation effects, including chloromethane (CH3Cl), were incorporated, employing the Integral Equation Formalism Polarizable Continuum Model (IEF-PCM) . This model is widely used in various studies to assess the optical properties of dyes .
3. Results and Discussion

3.1. Optimized Ground-state Geometries

The optimized geometries of the studied dyes R, M1–M4 at a B3LYP/6-31G(d,p) level in their ground states are shown in Figure 1b. The values of the selected structural parameters (di and ɸi), mentioned in Scheme 1, were extracted and listed in Table 1. As shown in Scheme 1, ɸ1 and d1 are the dihedral angle and bond length between the donor (D) and internal acceptor (A´) respectively. ɸ2 and d2 are the dihedral angle and bond length between internal acceptor (A´) and π-spacers while ɸ3 and d3 are corresponding to the dihedral angle and bond length of π-spacer and anchoring acceptor (A).
Scheme 1. Model structure of D-A´-π-A dyes.
Table 1. Selected bond angles (in °) and bond lengths (in Å) of all the dyes calculated at B3LYP/6-31G(d,p) level of theory.

Dye

ɸ1

ɸ2

ɸ3

d1

d2

d3

R

-50.25

1.61

0.01

1.481

1.456

1.426

M1

50.28

-1.76

0.03

1.481

1.455

1.429

M2

41.08

-0.52

-0.23

1.464

1.432

1.425

M3

-20.83

-2.20

0.48

1.449

1.430

1.429

M4

-31.06

-4.89

0.25

1.448

1.432

1.431

From Table 1, it can be observed that the dihedral angle (ɸ1) for all the dyes vary between -50° and 50°. This non-planarity of the structure is important as it may reduce dye aggregation. Moreover, M2, M3 and M4 have smaller absolute value ɸ1 (about 20°– 40°) than that of R and M1. It means that variation of the internal acceptor groups affects noticeably the process of charge transfer process from the donor (D) to the internal acceptor (A´). However, planarity is maintained between the internal acceptor group and the π-bridge (ɸ2), and between the π-bridge and the anchoring acceptor (ɸ3). This planarity may facilitate intramolecular charge transfer from the π-bridge to the anchoring group. On the other hand, the inter-cyclic link lengths (d1, d2, d3) are all about 1.4 Å. This value lies midway between the distances associated with a singular link and a double link. The reduction in length is attributed to the impact of conjugation within the examined systems. The coplanar arrangement, coupled with the intramolecular charge transfer facilitated by the conjugation effect in these systems, is anticipated to enhance the likelihood of π-stacking and, consequently, facilitate charge transport.

3.2. Electronic Properties and Frontier Molecular Orbitals (FMOs)

In order to evaluate the efficiency of electron injection and regeneration of the sensitizers, the HOMOs, LUMOs and energy gaps of the investigated dyes were calculated and shown in Figure 2. Obviously, all molecules have higher LUMO than the conduction band (CB) of TiO2 (-4.0 eV) , and lower HOMO than the redox potential of I-/ I3- (-4.8 eV) , which demonstrates that the excited dyes can be reduced by redox couple, and excited electrons can effectively inject to the CB of TiO2. Therefore, all invested molecules are effective dyes. The energy gap (Egap) was calculated as the difference between the energy levels HOMO and LUMO and is listed in Table 2. From this table, the energy gaps (Egap) of all designed dyes decrease in the order: R (2.207 eV) > M1 (2.137 eV) > M2 (2.077 eV) > M3 (1.913 eV) > M4 (1.733 eV). It shows that the modification of the cyanoacrylic acid by 2-(1,1- dicyanomethylene) rhodanine acid unit in M1 has positive effet in the decrease of Egap relative to R. Further, when changing the internal acceptor group the band gap is reduced greatly. The most interesting finding is the much lower Egap value for M4 compared to other studied dyes; this is due to the strong electron-withdrowing ability of 2,5-dihydropyrrolo [3,4-c] pyrrole-1,4-dithione and lead to the electrons being more easily excited and thus favorable for getting bathochromic shift of the absorption band, which may make contributions to higher power conversion efficiency.
Table 2. Energy values of HOMO, LUMO and Egap of all dyes.

Dye

 EHOMO(eV)

 ELUMO(eV)

Egap(eV)

R

-5.327

-3.120

2.207 (2.13)[a]

M1

-5.326

-3.189

2.137

M2

-5.230

-3.152

2.077

M3

-5.186

-3.273

1.913

M4

-5.272

-3.539

1.733

TiO2

-

-4.000

-

[a] Experimental values in parentheses are from ref
Figure 2. Sketch of B3LYP/6-31G (d,p) calculated energies of the HOMO, LUMO level of studied dyes.
To gain an insight into the intramolecular charge transfer (ICT), the frontier molecular orbitals (FMOs) of HOMO and LUMO are depicted in Figure 2. From this figure we observe that in the electron distributions of HOMOs are localized on donor, internal acceptor and spacer unit, while the LUMOs are essentially localized on internal acceptor, spacer and anchoring acceptor unit. Examination of the HOMO and LUMO of these dyes indicates that HOMO–LUMO excitation moves the electron distribution from the donor unit to the acceptor.

3.3. Photovoltaic Properties

Overall efficiency of photo-elution conversion in DSSCs is determined by the integral for JSC (short-circuit photocurrent density), Voc (open circuit photovoltage), FF (fill factor) and Pinc (incident photon to current efficiency) from equation :
η= Jsc Voc FFPinc(1)
Therefore, η can be enhanced by increasing JSC and Voc.
Theoretically, the maximum open circuit photovoltage (Voc) of the DSSC is determined by the difference between the LUMO of the donor (ELUMO of the dye) and the LUMO of the acceptor ECB=-4.0 eV of the conduction band of semiconductor TiO2) according to the following relationship :
Voc=ELUMO-ECB(2)
On the other hand, JSC is related to the efficiency of electron injection ɸinj, the charge collective efficiency (ηcollect) and the light harvesting efficiency at a given wavelength (LHE) via the following expression :
Jsc=λ LHE λ ϕinj ηcollect (3)
For the same DSSCs with only different dyes, it is reasonable to assume that ηcollect is constant . However, to know theoretically the relation between the Jsc and ƞ, we have studied the LHE and ɸinj from Eq. (3), to obtain a high Jsc, the efficient dyes used in DSSCs must have a large LHE that can be expressed as follows :
LHE=1-10f(4)
while f represents the oscillator strength of dye molecules at a specific wavelength.
For a larger light-harvesting efficiency (LHE), the oscillator strength obtained must be greater. In addition, a large ɸinj based on Eq. (3) could give a Jsc. The ɸinj is linked to the driving force of the injection ΔGinject by :
ΔGinject=Edye*- ECB= Edye - E00 - ECB(5)
where Edye* and Edye are the oxidation energy of the excited dye and the oxidation potential energy of the dye in ground state, respectively. While E00 is electronic vertical transition energy corresponding to λmax.5)
Table 3. Estimated electrochemical parameters for all dyes.

Dye

Edye

 Edye*

ΔGinject

LHE

Voc

R

5.327

3.355‬

-0.645

0.737

0.88‬0

M1

5.326

3.363‬

-0.637

0.853

0.811‬‬

M2

5.230

3.388

-0.612

0.925

0.848

M3

5.186

3.415‬

-0.585‬

0.968

0.727

M4

5.272

3.628

-0.371

0.888

0.461

The parameters mentioned above (Edye, Edye*, ΔGinject, LHE and Voc) of all the dyes were calculated and presented in Table 3. From this table, the Edye* energy values increase in the order R < M1 < M2 < M3 < M4, revealing that the R dye is the most readily oxidized molecule among the studied dyes, while M4 is the least. For ΔGinject, a larger absolute value of ΔGinject will be conducive to the electron injection and then improve the JSC. As shown in Table 3, all values are negative, this shows that charge injection are thermodynamically favorable for all designed dyes. The ΔGinject energy values increase in the order: R < M1 < M2 < M3 < M4. In comparison to R, the ΔGinject value increased (less negative) when replacing the cyanoacrilic acid by 2-(1,1- dicyanomethylene) rhodanine acid, in dye M1 (-0.637 eV). Further when changing the internal acceptor group, the driving force for injection ΔGinject is heighten greatly to -0.612, -0.585, -0.371 eV, in M2, M3, M4, respectively; therefore, the order of the driving force of the dyes is R > M1 > M2 > M3 > M4. To get an overview of the photocurrent performance of these dyes, the light-harvesting efficiency (LHE) should be as large as possible to maximize the photocurrent response. From Table 3, we can see that M2 (0.925) and M3 (0.968) display the largest LHE, which makes these designed dyes exhibit stronger light absorption capacity. On the other hand, the values of open-circuit photovoltage (Voc) of the studied dyes range from 0.461 eV to 0.880 eV, these values are sufficient for a possible efficient electron injection of electrons into the LUMO of the TiO2 semiconductor.

3.4. Optical Properties

Table 4. TD-DFT data of R dye calculated using different functionals.

Functional

λmaxa/(nm)

εa /(M-1.cm-1)

B3LYP

455, 676

30466, 21228

BHandLYP

386, 498

21963, 41746

CAM-B3LYP

381, 484

19263, 44112

PBE0

502, 921

22378, 15295

mPW1PW91

437, 628

31248, 23900

Experimental*

405, 489

33269, 20545

a Maximum absorption wavelength λmax and molar extinction coefficient at  λmax of dyes
* Experimental values in CH3Cl
Table 5. Computed absorption maxima (λmax), excitation energies (Eex), oscillator strengths (f) and the contribution of the most probable transition of the studied dyes in chloromethane solvent using TD/ mPW1PW91/6-31G(d,p) level of theory.

Dye

λmax(nm)

Eex(eV)

f

Main composition

R

628.58

1.972

0.582

H → L (0.69)

437.66

2.833

0.735

H-2 → L (0.69)

M1

631.48

1.963

0.835

H → L (0.69)

471.73

2.628

0.904

H-1 → L (0.63)

M2

673.11

1.842

1.128

H → L (0.70)

482.58

2.569

0.661

H-1 → L (0.52)

M3

699.75

1.772

1.498

H → L (0.70)

410.08

3.023‬

0.489

H-3 → L (0.66)

M4

754.40

1.644

0.953

H → L (0.70)

503.92

2.460

0.136

H → L+1 (0.53)

H= HOMO; L= LUMO; H-1=HOMO-1; H-2=HOMO-2; H-3=HOMO-3; L+1=LUMO+1
The determination of the optical properties of these dyes is carried out by TD-DFT method. For the consideration of the reliability of theoretical method, five different functionals were used, including B3LYP, BHandLYP, CAM-B3LYP, PBE0 and mPW1PW91. Table 4 shows the resulted maximal absorptions for R at different functionals in comparison with the experimental absorption. The λmax obtained at mPW1PW91 functional is closer to the experimental spectrum; therefore, mPW1PW91 functional was the most reliable to investigate the absorption spectra. So, the absorption spectra for all of dyes were calculated at mPW1PW91/6-31G(d,p) method. The calculated data of absorption wavelengths (λmax), electronic vertical transition energies (Eex) and oscillator strengths (f) of all dyes in solvent (CH3Cl) were carried out and listed in Table 5 and the corresponding simulated absorption spectra illustrated in Figure 3.
We can see that all the dyes absorb in the visible and assign to the ICT transitions. Compared with dye R, the substitution of the cyanoacrylic acid group (R: 602 nm) by 2-(1,1-dicyanomethylene) rhodanine moiety (M1: 593 nm) weakly affects the value of λmax. Further when changing the internal acceptor group the absorption spectra is more redshifted. In the case of M2, the incorporation of 2-methylbenzotriazole unit displays a remarkable 42 nm red-shifting absorption than benzothiadiazole (M1). 2-methylbenzotriazole is expected to be a stronger electron-deficient unit than benzothiadiazole. Also, M3 showed a more red-shifted absorption of 68 nm than M1, which might enhance the light harvesting of the sensitizers. For, dye M4 displays a 123 nm red-shifted absorption band when compared to dye M1, due to the fact that the 2,5-dihydropyrrolo [3,4-c]pyrrole-1,4-dithione unit is a much stronger p-electron deficient unit also by their great electronic affinity.
Figure 3. Calculated UV-Visible absorption spectra in chloromethane of all dyes by mPW1PW91/6-31G(d,p).
4. Conclusions
The Density functional theory (DFT) and time-dependent DFT (TD-DFT) methods have been used to investigate the performance of some benzocarbazole-based dyes as sensitizers in the dye-sensitized solar cells (DSSCs). The geometry structures, energy levels, absorption information, ICT property and electrons recombination process have been analyzed. Results showed that variation of functionalized internal acceptor (A’) had a significant effect on the optoelectronic and chemical properties. The designed molecules M1-M4 showed smaller energy gaps (from 2.137 to 1.733 eV), improved intramolecular charge transfer between electron donor and acceptor and enlarged absorption range in the visible region (from 631.48 to 754.40 nm) compared to R (2.207 eV/ 628.58nm).
For new designed benzocarbazole-based dyes, M4 containing 2,5-dihydropyrrolo [3,4-c]pyrrole-1,4-dithione will display better energetic, electronic and optical parameters compared with original molecules R and designed molecules M1-M3 for application in DSSC. The investigation provides guidance for experimental synthesis and developed new high-performance materials in the fields of DSSCs and photocatalysis.
Conflicts of Interest
The authors declare no conflicts of interest.
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    Etabti, H., Fitri, A., Benjelloun, A. T., Benzakour, M., Mcharfi, M. (2024). A DFT/TD-DFT Study of the Influence of Anchoring Group and Internal Acceptor of Benzocarbazole-based D-A´-π-A Dyes for DSSCs. International Journal of Computational and Theoretical Chemistry, 12(1), 1-9. https://doi.org/10.11648/j.ijctc.20241201.11

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    Etabti, H.; Fitri, A.; Benjelloun, A. T.; Benzakour, M.; Mcharfi, M. A DFT/TD-DFT Study of the Influence of Anchoring Group and Internal Acceptor of Benzocarbazole-based D-A´-π-A Dyes for DSSCs. Int. J. Comput. Theor. Chem. 2024, 12(1), 1-9. doi: 10.11648/j.ijctc.20241201.11

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    Etabti H, Fitri A, Benjelloun AT, Benzakour M, Mcharfi M. A DFT/TD-DFT Study of the Influence of Anchoring Group and Internal Acceptor of Benzocarbazole-based D-A´-π-A Dyes for DSSCs. Int J Comput Theor Chem. 2024;12(1):1-9. doi: 10.11648/j.ijctc.20241201.11

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  • @article{10.11648/j.ijctc.20241201.11,
      author = {Hanane Etabti and Asmae Fitri and Adil Touimi Benjelloun and Mohammed Benzakour and Mohammed Mcharfi},
      title = {A DFT/TD-DFT Study of the Influence of Anchoring Group and Internal Acceptor of Benzocarbazole-based D-A´-π-A Dyes for DSSCs
    },
      journal = {International Journal of Computational and Theoretical Chemistry},
      volume = {12},
      number = {1},
      pages = {1-9},
      doi = {10.11648/j.ijctc.20241201.11},
      url = {https://doi.org/10.11648/j.ijctc.20241201.11},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijctc.20241201.11},
      abstract = {Great attention is being shifted to Dye-sensitized solar cells because of their structural and electronic tunability, high performance, and low cost compared to conservative photovoltaic devices. In this work, the DFT/B3LYP/6-31G(d,p) and TD-DFT/mPW9PW91/6-31G(d,p) levels of theory are applied to the theoretical study of a new class of benzocarbazole-based D-A´-π-A dyes for their potential use in DSSCs. The influence of the internal acceptor on the optoelectronic properties is studied for the dyes. The optoelectronic and photovoltaic properties as HOMO, LUMO, Egap maximum absorption wavelength (λmax), vertical excitation energies (Eex), oscillator strength (f), light harvesting efficiency (LHE), open circuit voltage (Voc), injection force (ΔGinject), were evaluated and discussed in order to compare their performance as DSSC sensitizers. The theoretical results show that all dyes exhibit excellent optoelectronic properties, such as a lower Egap(1.733 eV to 2.173 eV), a significant λmax(631.48 nm to 754.40 nm), a sufficient value of Voc (0.461 V to 0.880 V) and high LHE (0.853 eV to 0.968 eV). In particular M4 with 2,5-dihydropyrrolo [3,4-c]pyrrole-1,4-dithione as auxiliary acceptor has the potential to be used as a sensitizer for DSSCs, due to its red-shifted absorption spectrum (λmax= 754.40 nm), and small energy gap (Egap=1.733 eV). Indeed, this study may help chemists to synthesize efficient dyes for DSSC.
    },
     year = {2024}
    }
    

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  • TY  - JOUR
    T1  - A DFT/TD-DFT Study of the Influence of Anchoring Group and Internal Acceptor of Benzocarbazole-based D-A´-π-A Dyes for DSSCs
    
    AU  - Hanane Etabti
    AU  - Asmae Fitri
    AU  - Adil Touimi Benjelloun
    AU  - Mohammed Benzakour
    AU  - Mohammed Mcharfi
    Y1  - 2024/04/29
    PY  - 2024
    N1  - https://doi.org/10.11648/j.ijctc.20241201.11
    DO  - 10.11648/j.ijctc.20241201.11
    T2  - International Journal of Computational and Theoretical Chemistry
    JF  - International Journal of Computational and Theoretical Chemistry
    JO  - International Journal of Computational and Theoretical Chemistry
    SP  - 1
    EP  - 9
    PB  - Science Publishing Group
    SN  - 2376-7308
    UR  - https://doi.org/10.11648/j.ijctc.20241201.11
    AB  - Great attention is being shifted to Dye-sensitized solar cells because of their structural and electronic tunability, high performance, and low cost compared to conservative photovoltaic devices. In this work, the DFT/B3LYP/6-31G(d,p) and TD-DFT/mPW9PW91/6-31G(d,p) levels of theory are applied to the theoretical study of a new class of benzocarbazole-based D-A´-π-A dyes for their potential use in DSSCs. The influence of the internal acceptor on the optoelectronic properties is studied for the dyes. The optoelectronic and photovoltaic properties as HOMO, LUMO, Egap maximum absorption wavelength (λmax), vertical excitation energies (Eex), oscillator strength (f), light harvesting efficiency (LHE), open circuit voltage (Voc), injection force (ΔGinject), were evaluated and discussed in order to compare their performance as DSSC sensitizers. The theoretical results show that all dyes exhibit excellent optoelectronic properties, such as a lower Egap(1.733 eV to 2.173 eV), a significant λmax(631.48 nm to 754.40 nm), a sufficient value of Voc (0.461 V to 0.880 V) and high LHE (0.853 eV to 0.968 eV). In particular M4 with 2,5-dihydropyrrolo [3,4-c]pyrrole-1,4-dithione as auxiliary acceptor has the potential to be used as a sensitizer for DSSCs, due to its red-shifted absorption spectrum (λmax= 754.40 nm), and small energy gap (Egap=1.733 eV). Indeed, this study may help chemists to synthesize efficient dyes for DSSC.
    
    VL  - 12
    IS  - 1
    ER  - 

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Author Information
  • Systems Engineering, Modeling and Analysis Laboratory, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdellah University, Fez, Morocco

  • Systems Engineering, Modeling and Analysis Laboratory, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdellah University, Fez, Morocco

  • Systems Engineering, Modeling and Analysis Laboratory, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdellah University, Fez, Morocco

  • Systems Engineering, Modeling and Analysis Laboratory, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdellah University, Fez, Morocco

  • Systems Engineering, Modeling and Analysis Laboratory, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdellah University, Fez, Morocco