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Inspired by the reference R with the IUPAC name ((Z)-2-(aminomethyl)-3-(5-((3-methyl-5-(7-(4-methyl-5-(5,10,15-trimethyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazol-3-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)ethynyl)furan-2-yl)acrylic acid)), six new organic (D–π–A) dyes for dye-sensitized solar cell (DSSC) applications have been designed. The designed molecules have an electron donor (D), triazatruxene, connected through different π-bridges and an electron acceptor (A), 2-cyanoacrylic acid. The key parameters of the optoelectronic and photoelectric performances were computed by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Compared to the original dye R, the designed compounds have a higher light harvesting ability with an absorption spectrum that appeared around the infrared region. The maximum absorption wavelength shifted to red from 78 nm to 148 nm, and the light-harvesting efficiency (LHE) curve broadened in the visible region and excellent electron injection efficiency was observed. All these contribute to better short-circuit current density (JSC) and power conversion efficiency (PCE). The results obtained through the global evaluation model for the reference dye R were JSC = 19.21 mA cm−2, VOC = 0.838 V, and PCE = 13.92%. These values are closer to the experimental results (JSC = 19.74 mA cm−2, VOC = 0.957 V, and PCE = 13.4%). The Tat-2 dye achieved a PCE of 23.75%. Therefore, it can be considered a candidate dye for high-yield DSSCs. [ABSTRACT FROM AUTHOR]

In this work, six molecules M1-M6, with the donor—π-spacer—acceptor structure, based on triphenylamine have been purposely studied to be applied in π-type dye-sensitized solar cells (DSSCs). We explore the effect of different electron-withdrawing substituents on the optoelectronic, structural, and photovoltaic dye properties. The key parameters of all the dyes affecting the power conversion efficiency (PCE) were theoretically investigated in detail using density functional theory (DFT) and TD-BHandHLYP calculations to reveal structure–property relationships. The calculated results show that the strong electron-withdrawing groups of thienothiadiazole and furano-thiadiazole, reduce energy gaps and provide a red shift of absorption spectra. The dye M1 and M3 have presented interesting optoelectronic properties with interesting charge transfer properties. Meanwhile, the enhanced free energy of charge injection (∆Ginject) and light-harvesting efficiency of the M5 dye revealed that this dye can be used as a potential sensitizer for TiO2-based DSSCs. The DFT method is also used to evaluate the bond interactions between the dye and iodine. The results suggest that dyes containing thienothiadiazole and furano-thiadiazole as π-spacers show more stable interactions with iodine species, thereby increasing the concentration of the redox couple at the surface of the semiconductor. In addition, the process of charge transfer and dye adsorption on (TiO2)9 cluster was investigated. Calculations show that the M3 dye has lower adsorption energy than the corresponding M1 dye. These results suggest that the adsorption of M3 on the TiO2 semiconductor would be more stable. The results indicate that the selected dyes provide promising results and motivate future investigations on these new systems. [ABSTRACT FROM AUTHOR]

The efficiency of the newly designed dye-sensitized solar cells (DSSCs) containing triphenylamine, diphenylamine (TPA), phenothiazine, and phenoxazine as donors and triazine, phenyl with D1-D2-π-linker-π-(A)2 architecture has been investigated using density functional theory (DFT) and time-dependent (TD-DFT) methods. These methods were used to investigate the geometrical structures, electronic properties, absorption, photovoltaic properties, and chemical reactivity. Furthermore, the calculated results indicate that different architectures can modify the energy levels of HOMO and LUMO and reduce the energy gap. The absorption undergoes a redshift displacement. This work aims at calculating the structural geometries and the electronic and optical properties of the designed dyes. Furthermore, the dye adsorption characteristics, such as the optoelectronic properties and the adsorption energies in the TiO2 clusters, were calculated with counterpoise correction and discussed. [ABSTRACT FROM AUTHOR]

The importance of the Density Functional Theory (DFT) calculation approach lies in their ability to provide a highly accurate prediction of structural and optoelectronic properties. However, the traditional methods of DFT failed to predict optoelectronic properties satisfactorily. Therefore, it will be necessary to examine methods containing different percentages of Hartree-Fock exchange and correlation in order to find the most suitable functionals. DFT and Time-Dependent-DFT (TD-DFT) calculations was carried out using four different functionals approximations incorporating a different amount of Hartree Fock exchange (B3LYP, BHandHLYP, CAM-B3LYP and LC-PBE), in order to evaluate their accuracies to predict the geometrical, optoelectronic and charge transfer properties of four triphenylamine-based dyes for Dye-Sensitized Solar Cells (DSSCs) applications. The functional hybrid B3LYP was the best among adopted functional that reproduced the geometrical, optoelectronic and charge transfer properties. On the other hand, it has been shown that the Hartree-Fock exchange percentage for BHandHLYP, significantly improved TD-DFT results in the case of organic dyes. Moreover, the corrected long-range functionals (CAM-B3LYP and LC-wPBE) present valuable tools for giving results of comparable precision with experimental optical data. In terms of the choice of the most appropriate functional for computational calculation, the obtained results can be useful for future DSSC applications. [ABSTRACT FROM AUTHOR]

By changing the π -linker groups and the anchor unit, six new organic dyes based on phenothiazine, phenoxazine, and phenohydrazine have been created in this work. Density functional theory (DFT) was used to examine their structure, electrical, and photovoltaic properties at the B3LYP/6-31G (d,p) level. In addition, the investigated dyes' charge transfer characteristics and electronic absorption spectrum in the CH 2 Cl 2 solvent were determined using the Time-Dependent DFT at the TD - BHandH/6-31G (d,p) level approach. Frontier molecular orbitals (FMOs), optoelectronic characteristics, and geometry parameters are examples of molecular properties. Through our research, we were able to demonstrate that every dye under study possesses noteworthy intramolecular charge transfer (ICT) capabilities, high light capture efficiency (LHE), and λ max in the range of 285–515 nm, with a range-wide band gap of 1.77–2.31 eV. The developed dyes with triazine, PhON, PhSN, and PhNN, have better geometric and optoelectronic properties than phenyl and -linker dyes. According to the theoretical calculations, these compounds could be exploited as potential sensitizers for DSSC applications. [Display omitted] • Dyes incorporating triazine exhibit nearly planar structures compared with those with phenyl rings. • Notably, the phenylhydrazine-based dye (PhNN) dye exhibits red-shifted absorptions compared to the other dyes. • Examination of the dyes@(TiO 2) reveals favorable adsorption onto the TiO 2 surface (negative adsorption energy). • The energies of FMO for the dyes@TiO 2 exhibit a noticeable shift in stabilization compared to the free dyes. • The analysis indicates that dyes containing triazine (PhON, PhSN, and PhNN) exhibit the highest levels of photovoltaic efficiency. [ABSTRACT FROM AUTHOR]

Six conformers of benzothiadiazole (BTD) flanked by two thiophenes on each side (T4) and mono-functionalized by phosphonic acid (A) (T4-BTDA) have been investigated by Density Functional Theory (DFT). The performance of six different functionals, namely Becke's three-parameter Lee–Yang–Parr (B3LYP) and B3PW91 with (Perdew and Wang correlation), BHandH, M06-2X, Coulomb-attenuating-method-B3LYP (CAM-B3LYP), and Grimme's D2 dispersion model (ωB97XD) in combination with four different basis sets of Pople's 6-31G(d), 6-31+G(d), 6-311G(d), and 6-311+G(d) have been assessed for the prediction of Frontier Molecular Orbitals (FMOs) and the maximum of absorption spectra in comparison with available experimental data. Computed results reveal that the most stable conformer in the solvent is favored by the sulfur–nitrogen (S–N) non-covalent interaction and the orientation of thiophene. Besides, it has been revealed that the anchoring group stabilizes the conformer when sulfur and oxygen of the phosphoryl group (P＝O) are in transposition. Regarding the available electronics experimental data of the studied dye, calculations showed that the B3PW91/6-311G(d) method was the right choice to obtain FMO energies, while the TD-BHandH/6-311G(d) method was suitable for simulating the spectral absorption for the studied dye. Using BHandH functional and (6-311G(d), LANL2DZ) basis sets, the adsorption energy on titania anatase 101 with a (TiO2)9 slab and the photovoltaic performance of studied dyes have been reported. The calculated cell performance was very close to the experimental value. This indicates that the calculation schema is consistent. [ABSTRACT FROM AUTHOR]

In this study, the photovoltaic properties and the effects of modifying phosphonic acid‐based dye‐sensitized solar cell (DSSC) via an electron‐withdrawing moiety were theoretically investigated using density functional theory methodology. According to the results, the inclusion of the CC and the electron‐withdrawing CN moieties exhibits a decrease in the highest occupied molecular orbital (HOMO)‐lowest unoccupied molecular orbital (LUMO) gap and a redshift in the absorption spectra. The photoelectric conversion efficiency (PCE) for the T4BTD‐A dye was estimated to be about 6.57% under the standard AM 1.5G solar radiation, which is in excellent agreement with its measured value of 6.40%, suggesting that the calculation scheme is consistent. In addition, the predicted PCE value after elongation of T4BTD‐A by CC and cyanure (CN) has increased to 7.11% and (7.82%, 8.09%), respectively. The addition of CN electron‐withdrawing moiety also enhances the PCE of the studied dyes, while the position of CN moiety has a slight effect on the PCE of the studied dyes. Finally, the calculation suggests that the CCCN1 and CCCN2 are good candidates as efficient sensitizers for DSSC applications. [ABSTRACT FROM AUTHOR]

The dye-sensitized solar cells containing a triphenylamine unit as the electron donor connected with a terminal cyanoacrylic acid electron acceptor by 2,2′-bithiophene as π-bridged (D-π-A) has been investigated by density functional theory (DFT) at the B3LYP/6-31G(d) level to shed light on the bridged effect on geometric and electronic properties of the designed dyes. Also, time-dependent DFT (TD-DFT) at a TD-BH and H/6-31+G(d)//BH and H/6-31G(d) level of theory was selected to modulate the electronic absorption spectra and charge-transfer properties of studied dyes. The calculated results show that the strong electron-withdrawing groups bridged the 2,2′-bithiophene efficiently, reduce the energy gaps and provide a red shift of the absorption spectra. The calculated absorption spectra in tetrahydrofuran (THF) are in good agreement with available experimental value for dye D1. Generally, the fundamental parameters, such as vertical and adiabatic ionization potentials (IPa/IPv), vertical and adiabatic electron affinities (EAa/EAv), electron extraction potentials and hole extraction potentials, including hole/electron reorganization energies (λ+/λ−), of studied dyes have been discussed. The improved electronic coupling constant (VRP), electron injection force (ΔGinject) and light-harvesting efficiency of dye D5 revealed that this dye can be used as a potential sensitizer for TiO2 nanocrystalline solar cells. [ABSTRACT FROM AUTHOR]

The efficiency of the designed dye-sensitized solar cells (DSSCs) containing phenothiazine phenoxazine, and 5,10-dimethylphenazine as donors and triazine, phenyl with D-A'-(π-A) 2 architecture has been examined utilizing Time-dependent (TD-DFT) and Density Functional Theory (DFT) techniques. The geometrical structures, electrical characteristics, absorption, and photovoltaic characteristics were studied using these techniques. Additionally, the computed findings show that various layouts can alter the HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) energy levels and reduce the energy gap between 1.63 and 2.30 eV. The absorption undergoes a redshift displacement. These bands are between 300 and 400 nm. This work aims at calculating the structural geometries and the electronic and optical properties of the designed dyes. In order to shed light on the bridging influence on geometric and TD-BHandH/6-31G(d) for optoelectronic properties, the density functional theory (DFT) and time-dependent TD-DFT at the B3LYP/6-31G(d) level were examined. Additionally, the complex dye@TiO2 cluster's binding energies have been investigated. [ABSTRACT FROM AUTHOR]

In this work, we study eight novel organic donor-π-acceptor dyes (Pi (i=1-8)), used for dye sensitized solar cells (DSSCs). The designed dyes are differentiated by the nature of the π-bridge linked the electron donor group N,Ndiethylaniline and the acceptor cyanoacrylic acid group. In this study Density Functional Theory (DFT) and its extensible Time Dependent DFT (TDDFT) approaches have been used to shed light on how the π-conjugation order influence the performance of the dyes in the DSSCs. The HOMO, LUMO and Gap energy of these compounds have been calculated and reported in this paper. Our aim is to explore their electronic and optoelectronic properties based on the DFT quantum chemical calculations. Also, we were interested to elucidate the parameters that influence the photovoltaic efficiency toward better understanding of the structure-property relationships. The study of the electronic and optical properties of these compounds could help design more efficient organic photovoltaic functional materials. [ABSTRACT FROM AUTHOR]

A variety of organic donor-acceptor-donor materials based on thienylbenzothiadiazole (BTD-5) combined with different -conjugated systems are studied by density functional theory (DFT) and time-dependent DFT (TD-DFT) for the ground- and excited-state properties, respectively, using B3LYP and the 6-31G(d, p) basis set. The effect of different electron-donor groups on the structural, electronic and optoelectronic properties is studied. To provide for the bandgap and to guide the synthesis of novel low bandgap materials, we applied quantum chemistry techniques to calculate the difference in the highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital LUMO energies. However, we have studied the effect of the reduction and oxidation properties on the electronic excitation transitions for all compounds. The emission energies have been obtained from TD-DFT calculations performed on the excited-state optimized S1 geometries. The theoretical results suggest that both the introduction of electron-donor groups and the doping process contribute significantly to the electronic and optoelectronic properties of the alternating donor-acceptor-donor conjugated systems studied. • Density functional theory used to examine the effect of different electron-donor groups on the structural, electronic and optoelectronic properties of thienylbenzothiadiazole. • The results suggest that both the introduction of electron-donor groups and the doping process contribute significantly to the electronic and optoelectronic properties of the alternating donoracceptor-donor conjugated systems. • To provide for the ban gap and to guide the synthesis of novel low band gap materials. [ABSTRACT FROM AUTHOR]

Polythiophene (PTh) and its derivatives are polymer-based materials with a π-conjugation framework. PTh is a useful photoelectric material and can be used in organic semiconductor devices, such as PLED, OLED, and solar cells. Their properties are based on molecular structure; the derivatives contain different substitutes in the 3 and 5 positions, such as electron-donating or electron-withdrawing groups. All molecular geometries were optimized at B3LYP/6-31G(d,p) level of theory. The energy gap (Egap) between the HOMO and LUMO levels is related to the π-conjugation in the PTh polymer backbone. In this study, the DFT calculations were performed for the nonsubstituted and 3,5-substituted variants to investigate the stability geometries and electrical properties. The theoretical calculations show that the substituted forms are stable, have low Egap, and are in good agreement with the experimental observations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The detailed DFT and TD-DFT calculations have been performed on novel D-π-A'-π-A phosphonic acid based dyes. • The studied dyes differ in the auxiliary acceptor moiety. • The electronic, optical and photovoltaic properties were studied. • BIA, BSD, BSED, and BTED dyes showed better optical and photovoltaic properties than the other dyes. Dye-Sensitized Solar Cells (DSSCs) that are based on a donor-bridge-acceptor-bridge-donor (D-π-A'-π-A) oligothiophene dye-containing benzothiadiazole mono-functionalized by a phosphonic acid were theoretically studied during the changing of the auxiliary acceptor (A') by six other auxiliary acceptors. To further understand the molecular structure of these series of dyes, a density functional theory (DFT) calculation was performed to study the molecular geometries, frontier molecular orbitals (FMO) by employing the method B3PW91 with the basis set 6-311G(d) for the soft atoms (H, C, N, O, P, Si, S) and LANL2DZ for the heavy atoms (Se, Te). The optical properties of the free and the adsorbed dyes were modelled using TD-DFT simulations employing the functional BHandH. The calculated absorption spectra of the designed dyes indicate that the change of electron-withdrawing groups increases the absorption wavelength significantly. Our results showed that the BTD, BXD, BTED, BSED, BIA, and BSD dyes exhibit a narrower HOMO–LUMO energy gap than BTZ dye. This led to a broader optical absorption and lower oscillator strength in dyes containing Benzimidazole, Benzosiladiazole, Benzoselenodiazole, and Benzotellurodiazole moieties that were verified to be better auxiliary acceptor units. The simulated absorption spectra of the adsorbed dyes on (TiO 2) 9 are red-shifted compared to the free dye. The adsorption energies of all dyes are similar which reveals that the adsorption energy is not depending on the auxiliary moiety but rather on the anchor group. Therefore, it is expected that the results obtained from this investigation will have a substantial impact on the development of DSSC of phosphonic acid-based dyes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel organic dyes bearing 2,3-diphenylquioxaline as an auxiliary acceptor and thiophene as π-spacers were efficiently synthesized. • PTZ, POZ, and CZ, the main electron donors linked with the tolyl unit as an auxiliary donor, constructed QX-D1 , QX-D2 , and QX-D3 , respectively. • The absorption spectra showed a redshift of the ICT band in the order QX-D2 > QX-D3 > QX-D1. • The overall data suggest that these dyes are suitable photosensitizers for DSSCs. Three novel D-D-π-A-π-A types of metal-free organic dyes, QX-D1 , QX-D2 , and QX-D3 , were designed and synthesized in excellent yields (94–99 %). An auxiliary acceptor of 2,3-diphenylquinoxaline was incorporated between two units of thiophene as π-spacers so that one ring is connected with cyanoacrylic acid as an anchoring electron acceptor, and the other one lies between the quinoxaline moiety and an electron donor to build the π-A-π-A part. The other D-D part of the dye skeleton was made using donors-based phenothiazine (PTZ), phenoxazine (POZ), and carbazole (CZ) containing a tolyl moiety as an auxiliary donor. For this purpose, an efficient multistep synthetic approach for the synthesis of the dyes was investigated. The chemical structures of all compounds were confirmed by spectral data (FTIR, 1H NMR, 13C NMR, and HRMS). The QX-D1 , QX-D2 , and QX-D3 dyes showed ICT bands in THF solution at 511, 542, and 526 nm, respectively and high molar absorptivity of 23434, 29825, and 23214 M−1 cm−1, respectively. Among the donor, QX-D2- based POZ revealed bathochromic and hyperchromic shifts in the absorption due to the influence of the oxygen atom in POZ compared with the sulfur atom and non in PTZ and CZ, respectively. The cyclic voltammetry data revealed that the HOMO and LUMO energy levels for QX-D1, QX-D2, and QX-D3 dyes were found to be (−5.07, −2.86 eV), (−4.90, −2.72 eV), and (−5.13, −3.04 eV), respectively. Furthermore, the density functional theory (DFT) and time-dependent TD-DFT at the B3LYP/6-31G(d) level were investigated to shed light on the bridged effect on geometric and TD-BH and H/6-31G(d) for optoelectronic properties. The binding energies of the complex dye@TiO2 cluster have also been explored. A good agreement between theoretical and experimental data was obtained. Thus, the dyes successfully achieved the desired outcomes, qualifying them for later use in photovoltaic applications such as sensitizers in dye-sensitized solar cells (DSSCs). [ABSTRACT FROM AUTHOR]

[Display omitted] • Carboxylic indolenine-based cyanine dyes with different donors were efficiently synthesized. • Three donors, dimethylaniline, carbazole and indole derivatives, were used to assemble novel D-π-A dyes. • The bathochromic shift was in the order D1 (dimethylaniline) > (D3) (indole) > D2 (carbazole). • The solvatochromic effect revealed a noticeable n-π* character overlapped with the ICT band in all dyes. • The optoelectronic and TD-DFT studies of D1-3 confirmed their validity as sensitizers in DSSCs. Three novel cyanine-based dyes (D1 - D3) were obtained by the carboxylic indolium salt the condensation reaction with three different donors, N, N -dimethylaniline, carbazole and indole derivatives. The chemical structures of these dyes were confirmed and fully characterized by IR, NMR, and HRMS. The UV–vis, fluorescence spectra, and cyclic voltammetry were conducted to give a preliminary insight into their optoelectronic properties. Generally, all synthesized dyes exhibited well-defined absorption in the visible region with high absorptivity and low band gap, giving λ Ex. max (516–564 nm), ε (45279–141011 M−1cm−1) and E 0-0 (2.11–2.21 eV). Distinctive stokes shifts were observed for all dyes, with the highest value for the dimethine cyanine containing carbazole donor, D2 , (2752 cm−1). The solvatochromic study showed hypsochromic effects and increased Stokes shifts with increasing solvent polarity. The electrochemical study on the other hand revealed having HOMO and LUMO energy levels, <-5.46, and > -3.58 eV, respectively, indicating their suitability as sensitizers in dye sensitized solar cells. The impact of different donors on the geometrical, photophysical, charge transfer and reorganization energy on the designed dyes has been investigated using Density Functional Theory (DFT) and time-dependent (TD-DFT). The theoretical and experimental results are in good agreement. The results indicate that the D1-D3 dyes have a small energy gap (2.50–2.77 eV) and their cationic counterpart absorption in the visible (480–576 nm). The modification of the donor suggests that these dyes would be suitable for dye-sensitized solar cells (DSCCs). [ABSTRACT FROM AUTHOR]

• Imidazole-phenothiazine dyes with different π-linkers were efficiently synthesized. • Benzene, furan, and thiophene were used as the π-linkers to construct novel d - d -π-A 6a-c dyes. • Furan revealed the highest redshift of absorption, followed by thiophene and benzene. • The photophysical, electrochemical, and TD-DFT studies of 6a-c dyes suggest their suitability in DSSCs application. Three newly designed phenothiazine-based dyes 6a-c were synthesized in good yield by introducing 1, 4, 5-triphenyl imidazole to phenothiazine skeleton linked to benzene, furan or thiophene π-linkers and connected with cyanoacrylic acid acceptor as the anchoring, respectively. UV–vis absorption and fluorescence properties of 6a-c were studied in different solvents. Among π-linkers, furan revealed the highest redshift of absorption, followed by thiophene and benzene. The dyes show intense visible absorption with high molar absorptivity; hence good light-harvesting dyes when used as sensitizers. The cyclic voltammetry data revealed that the HOMO energy levels of 6a-c were 5.36 eV for dye 6a and 5.42 eV for dyes 6b and 6c. Also, the energy LUMO levels of 6a-c were -3.10, -3.21, and -3.26 eV for dye 6a-c, respectively. Such well-matched energy levels of these dyes with those reported sensitizers would pave the way for their use in photovoltaic devices. Furthermore, these dyes were investigated by Density Functional Theory (DFT) and time-dependent TD-DFT to explore their potential as efficient dyes in photovoltaic devices. The geometrical structures, optoelectronic properties and charge transfer of these dyes were investigated. The results indicate that the 6a-c dyes have a small energy gap, absorption in the visible and higher oscillator strength. The modification of phenyl, furan and thiophene suggests that these dyes could be effective for dye-sensitized solar cells (DSSCs). [Display omitted] [ABSTRACT FROM AUTHOR]

In this article, we present the quantum result of six dyes based on thienopyrazine (D1–D6) with donor–π–acceptor structure (D–π–A) using DFT/B3LYP/6-31G(d,p) and TD-DFT/CAM-B3LYP/6-31G(d,p) levels. The donor unit varied and the influence was investigated. The study of structural, electronic, and optical properties of these dyes could help design more efficient functional photovoltaic organic materials. Key parameters in close connection with the short-circuit current density ( J sc ) including light harvesting efficiency, injection driving force (Δ G inject ), and total reorganization energy ( λ total ) are discussed in this work. [ABSTRACT FROM AUTHOR]