Synthesis, characterisation, optical and nonlinear optical properties of thiazole and benzothiazole derivatives: a dual approach

Polaronic state of conducting oligomer as a new approach to design non-lieaner optical materials: A case study of oligofurans

The geometric, electronic and nonlinear optical properties of neutral and polaron based oligofurans are studied comparatively. We have reported the role of polaron to trigger the nonlinear optical response of oligofurans (nFu). The polaron based oligomers show excellent opto-electronic properties. The effect of polaron on nFu* chains is measured by electronic properties i.e (ionization energy, electron affinity, band gap) and global reactivity descriptors like softness, hardness and chemical potential than their neutral counterpart. An interesting trends of reactivity descriptors have been observed. Lower band gaps (EH-L = 4.66 and 4.41 eV) are observed for polaronic systems as compared to their neutral counterpart. On the other hand, the TD-DFT study further demonstrated that, as the size of chain increases, the absorption maxima (λmax) also increases with significant reduction in excitation energies (ΔE). Furthermore, the nonlinear optical response is confirmed through the linear polarizability (αo), static first order hyperpolarizability (βo) and dynamic (frequency denepndent) hyperpolarizability. Electric filed induced second harmonic generation (EFISHG) and electro-optic pockle effect (EOPE) at 532 nm and 1064 nm, commonly used lasers frequencies have also been employed. Our results showed that the maximum hyperpolarizabilities are observed for polaron based 7Fu* and 9Fu* i.e 1.3 × 104, and 3.1 × 104 au. This study concluded that these polaron based organic polymers (nFu*) are useful as an efficient NLO material with vast applications in different fields.

Influence of acceptors on the optical nonlinearity of 5H-4-oxa-1,6,9-trithia-cyclopenta[b]-as-indacene-based chromophores with a push-pull assembly: a DFT approach

Herein, a series of compounds (TPD1-TPD6) having a D-π-A architecture was quantum chemically designed via the structural modulation of TPR. Quantum chemical calculations were employed to gain a comprehensive insight into the structural and optoelectronic properties of the designed molecules at the M06/6-311G(d,p) level. Interestingly, all the designed chromophores displayed narrow energy gaps (2.123-1.788 eV) and wider absorption spectra (λmax = 833.619-719.709 nm) with a bathochromic shift in comparison to the reference compound (λmax = 749.602 nm and Egap = 3.177 eV). Further, Egap values were utilized to evaluate global reactivity parameters (GRPs), which indicate that all the chromophores expressed higher softness (σ = 0.134-0.559 eV-1) and lower hardness (η = 4.155-4.543 eV) values than the reference chromophore. Efficient charge transfer from donors towards acceptors was noted through FMOs, which was also supported by DOS and TDM analyses. Overall, the TPD3 derivative exhibited a remarkable reduction in the HOMO-LUMO band gap (1.788 eV) with a red shift as λmax = 833.619 nm. Furthermore, it exhibited prominent linear and non-linear characteristics such as μtotal = 24.1731 D, 〈α〉 = 2.89 × 10-22 esu, and βtotal = 7.24 × 10-27 esu, among all derivatives. The above findings revealed that significant non-linear optical materials could be achieved through structural tailoring with studied efficient acceptors.

Investigation of photophysical and electronic properties of aurone derivatives: Insights from spectroscopic techniques and density functional theory calculations

This paper reports on a study of the photophysical properties, density functional theory (DFT) calculations, infrared (IR), ultraviolet (UV) and nuclear magnetic resonance (NMR) spectroscopic techniques of a series of aurone compounds. The photophysical properties were investigated using UV absorption and fluorescence spectroscopy in a dimethyl sulfoxide (DMSO) solution. Furthermore, the fluorescence quantum yields of the target compounds (1-24) were also investigated. Remarkably, these compounds revealed high quantum yields (Φ = 0.001-0.729) as compared to the already existing aurones in literature. The DFT calculations were performed to elucidate the electronic structure, energy levels and draw a comparison between experimental and theoretical findings. The simulated properties such as molecular frontier orbitals, the density of states, reactivity descriptors (GCRD), electrostatic potential distribution, transition density matrix, electron localization function (ELF) and localized orbital locator (LOL) have been calculated using DFT. The DFT calculations provided insight into the electronic structure and energy levels of the aurone compounds, while the IR and UV spectroscopy results shed light on their functional groups and electronic transitions, respectively. The results of this study contribute to a better understanding of the photophysical properties of aurone compounds and suggest their potential use in technological applications.

Unusual reaction of (E)-2-[(benzo[d]thia-zol-2-yl-imino)-meth-yl]-5-(di-ethyl-amino)-phenol with tri-phenyl-borane: crystal structures and optical properties

The mol-ecular and crystal structure of (E)-2-[(benzo[d]thia-zol-2-yl-imino)-meth-yl]-5-(di-ethyl-amino)-phenol (C18H19N3O2S, Et2N-Bz) and its unexpected reaction product with tri-phenyl-borane, 2,2-diphenyl-1,3-dioxa-2-borata-1,2-di-hydro-naphthalene [systematic name: N,N-diethyl-2,2-diphenyl-2H-1,3λ3,2λ4-ben-zodioxaborinin-7-amine, C23H24BNO2, (I)] are described. For Et2N-Bz, the hydroxyl group is involved in an intra-molecular hydrogen bond with the imino nitro-gen atom and the C=N bond displays an E configuration. The crystal packing is characterized by layers of inversion dimers parallel to the (10) plane and chains of mol-ecule in the a-axis direction formed through C-H⋯O inter-actions. Complex (I) crystallizes with two mol-ecules (A and B) in the asymmetric unit, which differ in the orientation of the ethyl groups. The 1,3-dioxa-2-borata-1,2,3,4-tetra-hydro-naphthalene ring displays a slight envelope conformation with the boron atom as the flap. In the crystal packing, chains of alternating A and B mol-ecules formed by C-H⋯O hydrogen bonds run in the b-axis direction. The UV-vis absorption and emission properties of the compounds are discussed and their aggregation-induced emission properties are further investigated.

Ab-initio and density functional theory (DFT) computational study of the effect of fluorine on the electronic, optical, thermodynamic, hole and electron transport properties of the circumanthracene molecule

In this paper, a systematic study of the electronic, optical, thermodynamic, optoelectronic, and nonlinear optical properties with RHF, B3LYP, wB97XD and BPBE methods using the cc-pVDZ basis set have been described to investigate the influence of fluorine (F) atom, which is an electron donor, on the circumanthracene (C40H16). Global reactivity descriptors, hole and electron transport properties were also calculated and compared with other studies on the same molecule. DFT/B3LYP results show that the undoped C40H16 molecule (Egap = 2.135 eV) and its fluorine-doped derivatives (C40F16 and C40H10F6) are semiconducting materials. However, doping the C40H16 molecule with the fluorine atom, partially or totally, favors the creation of a strong donor-acceptor system by considerably reducing its energy gap (Egap). The energy gap values of molecules doped using DFT/B3LYP method are 2.020 eV and 2.081 eV for the C40F16 and C40H10F6 molecules, respectively. These gap energies are below 3 eV, which favours the electronic properties of these molecules. They can be used to design organic solar cells. The nonlinear optical parameters were calculated and compared with those of urea. The values of βmol and μ calculated for C40F16 and C40H10F6 are higher than those of urea; this shows that these two materials have good nonlinear optical properties and therefore, are very good candidates for the design of optoelectronics and photonics devices. Futhermore, our results show that the perfluorination effect on the circumanthracene molecule increases the hole and electron reorganization energies, the vertical and adiabatic electron affinities and ionization energies, the optoelectronic and nonlinear optical properties, the transition excitation energy and the reactivity indices. The reorganization energies values suggest that these materials have promising transport properties. The natural bond orbital (NBO) analysis was also performed to determine the stability energy and charge delocalization in molecules. The theoretical results of the compounds studied in our work are in agreement with the experimental results. This confirms their molecular structures.

Quantum Chemical Exploration of A-π1-D1-π2-D2-Type Compounds for the Exploration of Chemical Reactivity, Optoelectronic, and Third-order Nonlinear Optical Properties

Organic compounds exhibit significant nonlinear optical (NLO) properties and can be utilized in various areas like optical parameters, fiber optics, and optical communication. Herein, a series of chromophores (DBTD1-DBTD6) with an A-π₁-D₁-π₂-D₂ framework was derived from a prepared compound (DBTR) by varying the structure of π-spacer and terminal acceptor. The DBTR and its investigated compounds were optimized at the M06/6-311G(d,p) level of theory. Frontier molecular orbitals (FMOs), nonlinear optical (NLO) properties, global reactivity parameters (GRPs), natural bonding orbital (NBO), transition density matrix (TDM), molecular electrostatic potential (MEP), and natural population analysis (NPA) were accomplished at the abovementioned level to describe the NLO findings. DBTD6 has the lowermost band gap (2.131 eV) among all of the derived compounds. The decreasing order of highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap values was DBTR > DBTD1 > DBTD2 > DBTD3 > DBTD4 > DBTD5 > DBTD6. The NBO analysis was carried out to describe noncovalent interactions such as conjugative interactions and electron delocalization. From all of the examined substances, DBTD5 showed the highest λ_max value at 593.425 nm (in the gaseous phase) and 630.578 nm (in chloroform solvent). Moreover, the β_tot and ⟨γ⟩ amplitudes of DBTD5 were noticed to be relatively greater at 1.140 × 10^-27 and 1.331 × 10^-32 esu, respectively. So, these outcomes disclosed that DBTD5 depicted the highest linear and nonlinear properties in comparison to the other designed compounds, which underlines that it could make a significant contribution to hi-tech NLO devices.

Efficient Synthesis, Spectroscopic Characterization, and Nonlinear Optical Properties of Novel Salicylaldehyde-Based Thiosemicarbazones: Experimental and Theoretical Studies

Currently, we reported the synthesis of six novel salicylaldehyde-based thiosemicarbazones (BHCT1-HBCT6) via condensation of salicylaldehyde with respective thiosemicarbazide. Through various spectroscopic methods, UV-visible and NMR, the chemical structures of BHCT1-HBCT6 compounds were determined. Along with synthesis, a computational study was also performed at the M06/6-31G(d,p) functional. Various analyses such as natural bond orbital (NBO) analysis, natural population analysis, frontier molecular orbital (FMO) analysis, and molecular electrostatic potential surfaces were carried out to understand the nonlinear optical (NLO) characteristics of the synthesized compounds. Additionally, a comparative study was carried out between DFT and experimental results (UV-vis study), and a good agreement was observed in the results. The energy gap calculated through FMOs was found to be in decreasing order as 4.505 (FHCT2) > 4.499 (HBCT6) > 4.497 (BHCT1) = 4.497(HMCT5) > 4.386 (CHCT3) > 4.241(AHCT4) in eV. The global reactivity parameters (GRPs) were attained through E _HOMO and E _LUMO, which described the stability and hardness of novel compounds. The NBO approach confirmed the charge delocalization and stability of the molecules. Among all the investigated compounds, a larger value (557.085 a.u.) of first hyperpolarizability (β_tot) was possessed by CHCT3. The NLO response (β_tot) of BHCT1-HBCT6 was found to be 9.145, 9.33, 13.33, 5.43, 5.68, and 10.13 a.u. times larger than that of the standard para-nitroaniline molecule. These findings ascertained the potential of entitled ligands as best NLO materials for a variety of applications in modern technology.

In silico screening of ethyl 4-[(E)-(2-hydroxy-4-methoxyphenyl)methyleneamino]benzoate and some of its derivatives for their NLO activities using DFT

The nonlinear optical (NLO) properties of ethyl 4-[(E)-(2-hydroxy-4-methoxyphenyl)methyleneamino]benzoate (EMAB) and some of its derivatives are investigated herein using the density functional theory (DFT) and time-dependent (TD)-DFT methods. The density functionals B3LYP, CAM-B3LYP, M06-2X and ωB97XD, and basis sets 6-31 + G**, 6-311 + + G** and Def2-TZVPP have been used. From the results, EMAB and its substituted derivatives studied are promising candidates for NLO materials. In all cases, the static first and second hyperpolarizabilities (31.7-86.5 × 10^-30 and 84.4-273 × 10^-36 electrostatic units (esu), respectively) and the frequency-dependent NLO properties are found to be significantly larger (about 43-103 and 28-76 times greater) than those of the NLO prototypical molecule, para-nitroaniline. Furthermore, the maximum absorption wavelengths of the molecules fall within the UV region of the electromagnetic spectrum. Relative to EMAB, the derivatives have shown improved transparency-nonlinearity trade-offs. Natural bond orbital (NBO) and density of states (DOS) analyses herein revealed effective charge transfer within the molecules studied, especially those with stronger electron donors than that in EMAB (methoxy group). Among the molecules studied, the derivative obtained by substituting EMAB's methoxy group with the pyrrolyl group was found to exhibit the best NLO properties. Conclusively, the NLO activities of EMAB can be significantly improved through the substitution of its methoxy group with stronger electron donors.

Two state "ON-OFF" NLO switch based on coordination complexes of iron and cobalt containing isomeric ligand: a DFT study

Coordination complexes are interesting materials for nonlinear optical (NLO) applications due to their large hyperpolarizability values. Moreover, switchable NLO response is also important in coordination complexes. Herein, we report two state ON-OFF switchable NLO contrast of coordination complexes of Fe and Co containing isomeric ligands. The optical, UV-visible, and electronic properties besides the "ON-OFF" switching effect are calculated using the CAM-B3LYP/6-31+G (d) method. The NLO responses of ligand-metal isomers are qualitatively evaluated through variation in charge transference (CT) style through TD-DFT. The higher β o in each isomeric pair is strongly dependent on the HOMO-LUMO gap. The isomer 4b with lowest HOMO-LUMO gap shows the highest NLO response. The charge transfer pattern in these complexes results in variation of their β o values. The notable β o contrast of 21.15 in isomeric pairs 3a and 3b makes these complexes a favorable material for genuine NLO switches. Hence, the outcome of the current investigation reveals that these ligand-metal isomeric complexes exhibit a two-state switch "ON-OFF" effect.

Influence of Peripheral Modification of Electron Acceptors in Nonfullerene (O-IDTBR1)-Based Derivatives on Nonlinear Optical Response: DFT/TDDFT Study

Fullerene-based organic compounds have been reported as useful materials with some limitations; nonetheless, fullerene-free compounds are primarily considered to be the most substantial materials for the development of modern technology. Therefore, in this study, a series of compounds (NFBC2-NFBC7) having an A-π-D architecture were designed for the first time from a synthesized nonfullerene (O-IDTBR) compound by changing different acceptor groups. The synthesized nonfullerene (O-IDTBR1) compound and its designed derivatives were optimized with frequency analyses at the M06/6-311G(d,p) level. These optimized structures were further characterized by different quantum chemical approaches. The study required that the designed compounds possess a low energy gap in comparison to that of O-IDTBR1 (2.385 eV). Moreover, density of state (DOS) calculations supported the FMO analysis and displayed charge transfers from the HOMO to the LUMO in an effective manner. The λ_max values of the investigated chromophores were observed to be greater than that of the reference compound. Amazingly, the highest amplitude of linear polarizability ⟨α⟩ and first (β_tot) and second hyperpolarizability values were achieved by NFBC6 at 1956.433, 2155888.013, and 7.868 × 10⁸ au, respectively, among all other derivatives. Effective NLO findings revealed that nonfullerene-based derivatives may contribute significantly to NLO technology.

Molecular modeling and nonlinear optical properties of new isostructural halogenated dihydroquinolinones

Two new isostructural halogenated dihydroquinolinones were synthesized and characterized by single crystal X-ray diffraction.

N-Arylation of Protected and Unprotected 5-Bromo-2-aminobenzimidazole as Organic Material: Non-Linear Optical (NLO) Properties and Structural Feature Determination through Computational Approach

The interest in the NLO response of organic compounds is growing rapidly, due to the ease of synthesis, availability, and low loss. Here, in this study, Cu(II)-catalyzed selective N-arylation of 2-aminobenzimidazoles derivatives were achieved in the presence of different bases Et₃N/TMEDA, solvents DCM/MeOH/H₂O, and various aryl boronic acids under open atmospheric conditions. Two different copper-catalyzed pathways were selected for N-arylation in the presence of active nucleophilic sites, providing a unique tool for the preparation of NLO materials, C-NH (aryl) derivatives of 2-aminobenzimidazoles with protection and without protection of NH₂ group. In addition to NMR analysis, all synthesized derivatives (1a–1f and 2a–2f) of 5-bromo-2-aminobenzimidazole (1) were computed for their non-linear optical (NLO) properties and reactivity descriptor parameters. Frontier molecular orbital (FMO) analysis was performed to get information about the electronic properties and reactivity of synthesized compounds.

Experimental and computational study of naphthalimide derivatives: Synthesis, optical, nonlinear optical and antiviral properties

The nonlinear optical (NLO) and antiviral properties of naphthalimide Schiff base compounds (5a-c) were experimentally and computationally investigated. The synthesized compounds (5a-c) were successfully characterized via UV-Vis, FTIR, ¹H NMR, fluorescence spectroscopy, and elemental analysis. The calculated average third-order NLO polarizabilities (˂γ˃) of 5a, 5b, and 5c were found to be 5, 9, and 21 times greater than the ˂γ˃ amplitude of p-NA, respectively. The computed results revealed the potential of the synthesized compounds for NLO applications. Additionally, molecular docking studies of the synthesized compounds with two crucial SARS-CoV-2 proteins were performed to examine their biochemical properties. Compound 5c exhibited a higher binding affinity with the spike protein compared to that with Mᴾᴿᴼ. The results obtained herein indicate the potential of the synthesized naphthalimide derivatives for optoelectronic and drug design applications.

de la Torre A, Khan MU, Raza AR, Kamal GM, Rehman MF, Alam MM, Imran M, Braga AA, Pertino MW. Facile Synthesis of Diversely Functionalized Peptoids, Spectroscopic Characterization, and DFT-Based Nonlinear Optical Exploration

Compounds having nonlinear optical (NLO) characteristics have been proved to have a significant role in many academic and industrial areas; particularly, their leading role in surface interfaces, solid physics, materials, medicine, chemical dynamics, nuclear science, and biophysics is worth mentioning. In the present study, novel peptoids (1-4) were prepared in good yields via Ugi four-component reaction (Ugi-4CR). In addition to synthetic studies, computational calculations were executed to estimate the molecular electrostatic potential, natural bond orbital (NBO), frontier molecular orbital analysis, and NLO properties. The NBO analysis confirmed the stability of studied systems owing to containing intramolecular hydrogen bonding and hyperconjugative interactions. NLO analysis showed that investigated molecules hold noteworthy NLO response as compared to standard compounds that show potential for technology-related applications.

Tuning the optoelectronic properties of superalkali doped phosphorene

In this study, the nonlinear optical (NLO) properties of pristine phosphorene and superalkali (Li₃O) doped phosphorene are estimated through the density functional theory (DFT) method to investigate the optical properties. The geometries of complexes have been optimized using the B3LYP/6-31G (d, p) level of theory. The effects of doping on phosphorene have been thoroughly explained by vertical ionization energy (VIE), interaction energies (E_int), and natural bond orbitals (NBO), Moreover, the density of states (DOS), electron density difference map (EDDM) analysis, the frontier molecular orbitals (FMO) plots are also given out to find more physical divination into the electronic communication and structure property relationship. The doping of superalkali conclusively has reduced the HOMO-LUMO energy gap of M1 3.28 eV-1.25 eV for M2 making it the n-type semiconductor. The higher values of E_int,E_fm and VIE obtained for M2 has indicated that this complex has higher stability and stronger interaction between superalkalis and phosphorene. More interestingly, there has been a gradual increase in the first static hyperpolarizability (β_static) values for M1, M2 and M3 are 115.75 au, 4118.6 au, and 659.30 au respectively. The Static second hyperpolarizability (γ_static) of the doped complexes has also been calculated from which the M2 has the highest value of 1382.5 ҳ 10³ au. The TD-DFT exploration has exhibited that the doped molecules are adequately transparent in the UV region. Some selected systems are also compared with the p-NA reference molecule which is a familiar external reference molecule for NLO applications. From UV absorption analysis, it can be found that these doped complexes of phosphorene may be contemplated as a new applicant for intense ultraviolet NLO materials. Computational studies have revealed the stability of M2 and M3 making them feasible as NLO materials in optoelectronic applications.

Second-order NLO properties and two-state switching effects of transition metal redox complexes of iron and cobalt: A DFT study

Designing switchable materials with large contrasts of nonlinear optical properties has been the focus of research in recent decades because of their widespread applications. Redox-active metal complexes due to charge transfer excitation are suitable to produce switchable nonlinear optical (NLO) material. In this regard, we present here the redox switchable NLO response of active metal complexes of iron and cobalt. The geometric, electronic, molecular absorption, nonlinear optical properties, and switch "ON/OFF" style of these metal complexes are studied at the CAM-B3LYP/6-31 + G(d) level of theory. NLO responses of these redox metal complexes are described in terms of change in the charge transfer (CT) patterns by time dependent density functional theory (TD-DFT). The highest β_o value of 301534 × 10^-30 esu is noticed in [Fe-ethynyl-ZnP]¹⁺ complex, because of obvious charge transfer transition from metal to ligand i.e meatal-ligand charge transfer (MLCT) in redox metal complex. In each redox metal isomeric pair, the greater hyperpolarizability value of individual isomer is quite consistent with its smaller energy gap (H-Lgap) between highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), low crucial excitation energy, and bathochromic shift of λ_max. The remarkable β_o contrasts of these isomeric redox complexes illustrate that they can be appropriate for effective redox-triggered NLO switches. Thus, the results reveal that these redox pair complexes show two-state switching "ON/OFF" effect.

Static- and frequency-dependent NLO properties of dithienothiophene and thienothiophene bridges — A computational investigation

We have explored detailed linear and nonlinear optical properties of push-pull systems bearing thienothiophene and dithienothiophene spacers. By using density functional theory (DFT), frequency-dependent strategies were applied to examine the polarizability ([Formula: see text] and hyperpolarizability ([Formula: see text] and [Formula: see text]. The set of global and range-separated hybrid functionals with different Hartree–Fock (HF) exchange percentage at two basis sets cc-pVDZ and cc-pVTZ were used to evaluate the nonlinear optical (NLO) properties. The observed trends in the absorption maxima supported by perturbation potential analysis; as the absorption maxima increases, the respective amplitude potential decreases. For the investigated compounds, [Formula: see text]-conjugation along with the type of substituted acceptor plays a crucial role in the enhancement of NLO properties. The presence of acceptor group and length of conjugation increase between the D and A group; the first- and second-order intrinsic hyperpolarizability increases, leads to enhanced first- as well as second-order hyperpolarizability. Bond length alternation (BLA)/bond order alteration (BOA) exploration suggested that compounds attain cyanine limit. The trends in NLO properties for investigated compounds are supported by chemical reactivity descriptors, hardness and hyperhardness analysis. The polarizability is linearly correlated with the hyperpolarizability parameters ([Formula: see text] and [Formula: see text] and shows a good regression coefficient by figures of merit analysis.

Efficient Synthesis, SC-XRD, and Theoretical Studies of O-Benzenesulfonylated Pyrimidines: Role of Noncovalent Interaction Influence in Their Supramolecular Network

Crystalline organic compounds, 2-amino-6-methylpyrimidin-4-yl benzenesulfonate (AMPBS) and 2,6-diaminopyrimidin-4-yl benzenesulfonate (DAPBS), were prepared via O-benzenesulfonylation of 2-amino-6-methylpyrimidin-4-ol 1 and 2,6-diaminopyrimidin-4-ol 2, respectively. The structural interpretations were achieved unambiguously by single-crystal X-ray diffraction (SC-XRD) analysis. The Hirshfeld surface study showed that C-H···O, N-H···N, and especially C-H···C hydrogen bond interactions are the key contributors to the intermolecular stabilization in the crystal. Density functional theory (DFT) studies were used to obtain a better understanding of natural bond orbitals (NBOs) and nonlinear optical (NLO) analysis for AMPBS and DAPBS at the B3LYP/6-311G(d,p) level. The time-dependent density functional theory (TD-DFT)/CAM-B3LYP/6-311G(d,p) level was employed for frontier molecular orbital analysis of both compounds. DFT-based vibrations for C-H, C=N, N-H, and stretching for C-C were found to be in good agreement with the experimental data. Overall, the theoretical findings were acquired in correspondence to the SC-XRD-based parameters. Intracharge transfer occurred in AMPBS and DAPBS compounds, which was evaluated through FMO activity. Global reactivity indices had been acquired utilizing energies of HOMO-LUMO orbitals. Overall, the theoretical findings related to AMPBS and DAPBS consist of promising correspondence to experimental findings. The theoretical-based study also exhibited that both AMPBS and DAPBS compounds contain promising NLO features.

Insight into the optoelectronic characteristics of diimide-based acceptors in organic solar cells by performing DFT calculation and molecular dynamics simulation

In order to compare the main difference of two diimide derivatives on the modulation of electronic and optical properties of P3HT-based organic solar cell, the density functional theory and molecular dynamics simulations were implemented to achieve elementary data on geometrical structure, molecular orbital, open-circuit voltage, absorption spectra, energetic driving force, and interface parameter of P3HT/D1 and P3HT/D2 systems. According to the investigation, P3HT/D1 system not only exhibits higher open circuit voltage and enough energetic driving force than P3HT/D2 system, but also possesses low-lying LUMO +1 orbital which can favor the exciton separation efficiency. Moreover, on the basis of some typical interface models choose from MD simulation, the estimation of the interface rate manifests that the P3HT/D1 interface possesses the smaller charge recombination rates and larger charge separation rates than those of the P3HT/D2 interface. It is expect that this work can provide certain guidelines for the further develop the performance of organic solar cell. We hope this work can further study on non-fullerene acceptor materials as a certain guides.

A systematic study of the effects of thionation in naphthalene dimide derivatives to tune their nonlinear optical properties

In the present study, the number and position of sulfur atoms on naphthalene diimide (NDI) is systematically investigated to tune its nonlinear optical (NLO) response properties. Our DFT calculations for third-order polarizability (γ) show that the thionation significantly influences the nonlinear optical property of NDI as it is seen among its several designed derivatives (NDI-1 to NDI-10). The smallest and the largest γ_zzzz amplitudes are 503.49 × 10^-36 and 1299.5 × 10^-36 esu for NDI-1 (having tetraone group) and NDI-10 (having tetrathione group), respectively. The increase in γ_zzzz amplitude for NDI-10 is 796 × 10^-36 esu, which is ∼150% from the γ_zzzz amplitude of NDI-1. A comparison of the γ_zzzz amplitudes of our designed derivatives are made with para-nitroaniline i.e. a prototype NLO molecule. The γ_zzzz amplitude of pNA is found to be 42.64 × 10^-36 esu at the same B3LYP/DZVP2 level of theory. Using two-level model, the origin of larger γ_zzzz amplitudes is traced in lower transition energy of NDI-10. Furthermore, the calculation of vertical ionization potentials (VIPs) shows that the thionation does not affect the stability of designed derivatives, where a slight difference of 0.06 eV is seen between the VIPs of NDI-1 (6.63 eV) and NDI-10 (6.57 eV). Thus, a systematic comparison of the third-order polarizability and other electro-optical properties of our designed derivatives shows that our derivative systems possess good potential for their practical realization in the field of optical and NLO materials.