Efficient Nonlinear Optical Materials Research Articles

Remarkably enhanced first hyperpolarizability and nonlinear refractive index of novel graphdiyne-based materials for promising optoelectronic applications: A first-principles study

A new functionalized graphdiyne-based structure was designed by adsorbing single and double AM3O (AM = Li, Na, K) on graphdiyne (GDY) surface, namely (AM3O)n@GDY (AM = Li, Na, K; n = 1, 2). Density-functional theory calculations have been used to unravel the relations between the geometric structure and nonlinear optical (NLO) properties, e.g., Hyper-Rayleigh Scattering coefficient (βHRS) and nonlinear refractive index (n2). The frequency-dependent electro-optic Pockel's effect (EOPE) and second-harmonic generation (SHG) were explored to design the efficient NLO materials. Our calculations reveal that the AM3O molecule has the strong interactions with the GDY unit, and the intramolecular charge transfer is significant for determining the NLO properties. Large first hyperpolarizabilities (βtot) for single-adsorbed GDY have been found, especially for K3O@GDY (∼3.06 × 105 a.u.), rather than double-adsorbed GDY. Moreover, the small transition energies with large oscillator strength are a decisive factor for enhancing the βtot values. In the dynamic NLO process, the EOPE and SHG resonances can be enhanced at ω = 0.10 a.u., while single-adsorbed GDY clusters have large nonlinear refractive index and improved Hyper-Rayleigh Scattering response. All of these results will inevitably stimulate further synthesis of GDY-based optoelectronic materials with high NLO properties for future applications.

Exploring the potential of novel transition metal complexes derived from ONO donor type ligand: a quantum chemical study.

In the present quantum chemical investigation, we predict several novel transition metal complexes which are designed using tridentate ONO donor type Schiff base ligand (2-((E)-((Z)-4-hydroxypent-3-en-2-ylidene) amino) phenol). The stable molecular geometries of newly designed metal complexes are obtained using density functional theory (DFT) methods. Several properties including geometrical parameters, energies of frontier molecular orbitals (FMOs), and interaction energies are calculated for optimized metal complexes. The more negative interaction energies illustrate more susceptibilities of the reaction of metal cations with ligand. The charge transfers from ligand to metals are observed in the d7 and d8 metal complexes while it is seen as backdonation of charge from metal to ligand in the d10 complexes. The quantum chemical characterizations are performed for calculating UV-visible spectra and IR frequencies for all the designed metal complexes. All designed metal complexes show multiple absorption peaks in UV region ranging from 184 to 376nm, which are related to metal to ligand and ligand to metal charge transfer processes. The IR frequency analysis shows that the -C=N- stretching frequency of ligand in the region of 1650-1580cm-1 is decreased by between 50 and 100cm-1, which may assign the coordination of ligand with metal via nitrogen. Moreover, the investigations of nonlinear optical (NLO) polarizabilities among selected complexes show that these complexes may possess good potential for NLO applications. The most interesting results are found about the third-order NLO polarizabilities (γ||) where the γ|| amplitudes are found to be 60.01 × 10-36, 56.48 × 10-36, 90.04 × 10-36, and 64.57 × 10-36esu for complexes 1, 2, 9, and 10, respectively. Thus, we believe that the present investigation may bring the newly designed metal complexes in the limelight of scientific interest for their practical realization in optical and nonlinear optical applications. Graphical abstract Several novel transition metal complexes are designed using tridentate ONO donor type Schiff base ligand as efficient NLO materials.

Donor-π-Acceptor-π-Donor class of 2,5-dibenzylidenecyclopentan-1-one analogues as efficient third order nonlinear optical and photoluminescent materials – An experimental investigation

In the present work, nonlinear optical (NLO) and optoelectronic investigations of four 2,5-dibenzylidenecyclopentan-1-one (bischalcone) analogues 1 (4-F), 2(4-Cl), 3(4-Br) and 4(3-NO2) with push-pull substituents (Donor-π-Acceptor-π-Donor) are studied. The third-order nonlinear optical measurements of bischalcone analogues carried out by Z-scan technique, which revealed that these compounds possess strong third-order nonlinear absorption (NLA), negative nonlinear refraction (NLR) and optical limiting behaviour under the illumination at 532 nm continuous wave laser beam (200 mW). The magnitude of third order NLA coefficient β, NLR index n2, and effective susceptibility χ(3) are found to be in the order of 10−5 cm/W, 10−12 cm2/W, and 10−7 e.s.u respectively. The β value varied with substitution at the phenyl ring which contributed immensely on the variation. Even though the deactivating effect of 4-F, 4-Cl, 4-Br and 3-NO2 groups contributed on polarization, the presence of electron rich cyclopentanone ring ameliorated the effect of deactivation. Hence these molecules are found to possess moderate NLA and NLR properties. In addition, photoluminescence activity of these flourophores(1–4) is observed as emission spectra in the range of 307–554 nm on shining at 279 nm with relative quantum yield of 1.81%, 3.8%, 1.62% and 0.89% respectively with reference to tryptophan. The HOMO-LUMO analysis for optical band gap ranged between 2.89 eV and 3.13 eV indicating polarizing nature varied with substituents.

Exploring the functional properties of Trimethoxy-Phenylpyridine as efficient optical and nonlinear optical material: A quantum chemical approach

In the current study, the 2,6-diphenyl-4-(3,4,5-trimethoxyphenyl)pyridine (compound 1) has been investigated as proficient material for optoelectronic and nonlinear optical (NLO) applications. In order to highlight the potential at both solid-state (bulk) and molecular levels, different electronic and optical parameters were investigated. The optical and electronic parameters such as refractive index, reflectivity, dielectric function, extinction coefficient, conductivity, electronic band structure, density of states (DOS) of newly reported trimethoxy-phenylpyridine at bulk (solid-state) level have been studied. The band gap is found to be 2.817 eV, which revealed the photon absorption competency has been improved in compound 1 due to narrow band gap and has the capability of containing the absorbed energy. Other calculated optoelectronic properties also revealed that the compound 1 might be better for semiconductor applications. Additionally, the geometric parameters, polarizability (isotropic and anisotropic) and third-order NLO polarizability have been computed at molecular level. For compound 1, its isotropic and anisotropic values are found to be 63.41 × 10−24 esu and 46.22 × 10−24 esu, respectively. The calculated γ amplitude for studied material has been computed as 187.53 × 10−36 esu that is about 25 times bigger than that of the γ amplitude for pNA (a prototype NLO molecule). The third order NLO response for compound 1 has been further tuned through the designing of its further derivatives in the form of compounds 1a, 1b and 1c. Thus, the present study highlights the important optoelectronic and NLO properties of compound 1 and its derivatives.

Zinc oxide encapsulated poly (vinyl alcohol) nanocomposite films as an efficient third-order nonlinear optical material: Structure, microstructure, emission and intense low threshold optical limiting properties

Keeping in view the significant facts on Zinc Oxide (ZnO) and Poly (Vinyl Alcohol) (PVA), we developed nanocomposite films comprising small weight percentage of ZnO content in host polymer PVA, choosing a simple and cost-effective method based on solution-casting. The investigations of its structure, microstructure, linear/luminescence and nonlinear optical properties are presented. This article mainly discusses the intense low threshold nonlinear absorption (NLA) behaviour displayed by the samples, as studied using the standard Z-scan technique. On either increasing the intensity or ZnO content, the samples exhibited a switchover from saturable to reverse saturable absorption, which is rarely observed under 442 nm continuous wave (CW) laser light excitation. The effective values of nonlinear absorption coefficient and imaginary part of third-order nonlinear susceptibility are higher than the recently reported results. The limiting threshold values (obtained from optical limiting curves) are also found to be much better than other reported ones.

A dual approach to study the key features of nickel (II) and copper (II) coordination complexes: Synthesis, crystal structure, optical and nonlinear properties

In the present study, we use a dual approach comprising of experimental and computational techniques to report the syntheses and characterizations of two novel nickel (II) [Ni(L)2] (1) and copper (II) [Cu(L)2] (2) coordination complexes, which are made through the coordination of 1-(E-(2, 4-dibromophenylimino) methyl) naphthalene-2-ol (HL) ligand. Several modern techniques including experimental electronic spectroscopy, single crystal X-ray crystallography and quantum computational methods are used to characterize the isolated coordination compounds. Both the complexes display a square planar trans-[MN2O2] coordination geometry, whose central M (II) atoms lie on the centre of symmetry. Complexes [Ni(L)2] (1) and [Cu(L)2] (2) crystallize in the monoclinic system of the space groups P21/c with a = 9.307(4)Å, b = 12.242(4)Å, c = 13.823(4)Å, α = 90°, β = 105.262(10)°, γ = 90° and Z = 2 for complex (1), a = 9.171(5) Å, b = 12.507(8) Å, c = 13.666(8) Å, α = 90°, β = 103.823(15)°, γ = 90°, and Z = 2 for complex (2). The ligand (HL) is coordinated as monobasic bidentate with N and O donor groups suitably oriented for forming two six membered chelate rings. State of the art quantum computations are performed at molecular and bulk levels to get structure-property relationships from molecule to materials. The molecular nonlinear optical (NLO) response properties including third-order polarizability (γ) are calculated using density functional theory (DFT) methods. The calculated γ amplitudes for the synthesized [Ni(L)2] (1) and [Cu(L)2] (2) complexes are found to be 444.09 × 10−36 and 567.03 × 10−36 esu, respectively. These γ amplitudes of [Ni(L)2] (1) and [Cu(L)2] (2) complexes are about 21 and 27 times larger than that of standard para-nitroaniline (PNA, a prototype NLO molecule), respectively, which show the potential of these complexes as efficient NLO materials. Additionally, several important optical parameters including dielectric function, reflective index, reflectivity, conductivity and loss function are calculated at bulk level using ab initio methods within periodic boundary conditions (PBC). The obtained results indicate that both coordination complexes has good optical and NLO properties, which may render the above entitled complexes as efficient candidates for optoelectronic and NLO device fabrications.

Quantum chemical design of triple hybrid organic, inorganic and organometallic materials: An efficient two-dimensional second-order nonlinear optical material

In the present report, a quantum chemical study is presented through the designing of triple hybrid nonlinear optical (NLO) materials comprising of organic, inorganic and organometallic moieties. The designed compounds possess two-dimensional (2-D) NLO properties with significantly larger values of their nonlinear anisotropy, which is due to their unique V-shaped configurations. Interestingly, the incorporation of ferrocenyl moieties causes remarkable enhancements in the NLO response properties of designed compounds. For instance, the ferrocenyl containing compounds IA3 [2,4-diido, 6,9-di-(1-ethynyl-4-methylbenzene ferrocenyl) decaborane and IA4 [2,4-diido, 6,9-di-(1-methyl-4-((4-(prop-1-yn-1-yl)phenyl)ethynyl)benzene ferrocenyl) decaborane are found to possess notably larger amplitudes of their first hyperpolarizabilities mounting to 34.95 × 103 and 331.50 × 103 a.u., respectively. The additional substitutions of diiodo groups at 2, 4 positions of decaborane basket not only improves the NLO response but also causes further stability as indicated by vertical ionization potentials (VIPs) of all the systems in group-A. Furthermore, a structure-NLO property relation is established using TD-DFT calculations along with frontier molecular orbital (FMOs) diagrams as well as total and partial density of states (TDOS and PDOS). It is expected from the results of the present investigation that these triple-hybrid compounds can be potential candidates for NLO applications possessing additional advantages of their 2-D NLO characters and better thermal stabilities.

Nonlinear optical responses of carbon quantum dots anchored on graphene oxide hybrid in solid-state transparent monolithic silica gel glasses

Exploring the nonlinear optical (NLO) response of graphene-based hybrids in solid-state three-dimensional macrostructures is vital to promote the practical development of graphene-based photonic and optoelectronic devices. Here, a solid-state hybrid of ultrafine and well-dispersed carbon quantum dots (CQDs) supported on graphene oxide (GO) was chosen as representative of such materials. The hybrid was introduced into organically modified silica gel glasses using a facile sol-gel wet chemical technique to obtain stable transparent monolithic nanocomposites, and their practical application in nonlinear optics was explored. The NLO performances were investigated by the open-aperture (OA) and closed-aperture (CA) Z-scan techniques in the nanosecond regime using a laser with a wavelength of 532 nm. The as-prepared CQD/GO SiO2 gel glasses displayed completely different NLO behavior from that of a CQD/GO suspension. The NLO performance of CQD/GO significantly improved after incorporation into SiO2 gel glasses because of the more graphitized structure of the CQD/GO hybrid. Both the OA and CA Z-scan patterns suggested that the NLO properties of the CQD/GO suspension combined nonlinear absorption and nonlinear scattering, while the NLO response of the CQD/GO SiO2 gel glasses stemmed primarily from nonlinear absorption and nonlinear refraction. In addition, this is the first report of the third-order nonlinear susceptibility χ(3) of a CQD/GO hybrid doped in solid-state gel glasses. The present results therefore demonstrate the feasibility and versatility of CQD/GO silica gel glasses, a promising new class of highly efficient NLO materials that can be applied in optical communications, radiofrequency optoelectronics, and all-optical signal processing.

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

In the present investigation, we employ a dual approach consisting of experimental and computational techniques to synthesise and characterise the Schiff-base including the moieties of nitrophenyl (3), nitrothiazole (5) and nitrobenzothiazole (7). The synthesised Schiff bases are confirmed by FT-IR, 1H-NMR and UV-visible spectroscopic techniques. The experimental UV-visible spectroscopic results are compared to the theoretically calculated TD-DFT results. There is a reasonably good agreement between the experimental and the theoretically calculated spectroscopic results. We also calculate the third-order nonlinear optical (NLO) polarizability (γ) of above entitled derivatives using finite field (FF) approach and DFT methods. The compound 7 shows an amplitude of γ as large as 124.15×104 a. u., which is found to be several times larger than that of para-nitroaniline. Moreover, the partial and total density of states (PDOS and TDOS) along with electrostatic potential maps are calculated to get more physical insights into the structure-property relationship and electronic communications between terminal donor and central core acceptor moieties in the synthesised compounds. The present investigation highlights the significance of indigenously synthesised nitrothiazole and nitrobenzothiazole compounds as efficient NLO materials, which may evoke the interest of scientific community in such efficient NLO materials for their potential utilization in device applications.

Exploring the novel donor-nanotube archetype as an efficient third-order nonlinear optical material: asymmetric open-shell carbon nanotubes.

Contrary to the enormous number of previous studies on carbon nanotubes (CNTs), herein, we realized the origin of the intrinsic open-shell diradical character and second hyperpolarizability γ using a broken symmetry approach. This study was inspired by our recent findings (S. Muhammad, et al., Nanoscale, 2016, 8, 17998 and Nakano, et al., J. Phys. Chem. C, 2016, 120, 1193). We performed structural modifications through a unique asymmetric donor-nanotube framework, which led to a novel paradigm of modified CNTs with tunable open-shell diradical character and remarkably superior NLO response properties. Interestingly, asymmetry and diradical character were found to be the crucial factors to modulate the second hyperpolarizability γ. We initially performed a comparative analysis of the diradical characters and γ amplitudes of boron nitride nanotubes (BNNTs) and CNTs possessing significant ionic characters and covalent characters, respectively. The basic findings for these simple configurations were further extended to the donor-acceptor CNT paradigm, which finally led to excellent asymmetric donor-CNT configurations with remarkably larger γ amplitudes. Furthermore, among the CNTs, finite length zigzag CNT(6,0)3 were modified with different donor-acceptor configurations. Interestingly, for the first time, unique donor-nanotube configurations [1,4-(NH2)2CNT-(6,0)3 and 1,4-(NH2)2CNT-(6,0)5] were found; they showed significantly robust γ amplitudes as large as 2519 × 103 and 4090 × 103 a.u. at the LC-UBLYP(μ = 0.33)/6-31G* level of theory. Additionally, several molecular level insights have been obtained for these novel donor-nanotube configurations using their odd electron densities, molecular electrostatic maps, densities of states and γ density analyses to highlight the realization of these novel materials for highly efficient optical and NLO applications.

Triphenylamine Derived 3-Acetyl and 3-Benzothiazolyl Bis and Tris Coumarins: Synthesis, Photophysical and DFT Assisted Hyperpolarizability Study

Triphenylamine derived bis- and tris-branched donor-pi-acceptor coumarins with acetyl and benzothiazolyl acceptors are studied for their linear and nonlinear optical properties that originate from their photophysical and molecular structure. Plots of solvent polarities versus the Stokes shift, frontier molecular orbital analysis and Generalised Mulliken Hush analysis have established their strong charge transfer character supported by the strong emission solvatochromism of these chromophores. On the basis of excited state intramolecular charge transfer, the first-, second- and third-order polarizability of these dyes are determined by a solvatochromic method and supported by density functional theory calculations using CAM-B3LYP/6-31g(d). Compared to the acetyl group, the benzothiazolyl group is a strong acceptor, and its corresponding derivatives show enhanced absorption, emission maxima and non-linear optical response. Bond length alternation and bond order alternation analysis reveals that these chromophores approach the cyanine-like framework which is responsible for maximum perturbation to produce high nonlinear optical response. Third order nonlinear susceptibility for dyes 1 and 2 is determined by Z-scan measurement. All of these methods are used to determine the nonlinear optical properties, and thermogravimetric analysis suggests that these chromophores are thermally robust and efficient nonlinear optical materials.

Strong optical nonlinearities of self-assembled polymorphic microstructures of phenylethynyl functionalized fluorenones

Highly efficient nonlinear optical (NLO) materials with well-defined architectures in the wavelength and subwavelength length scales are of particular importance for next generation of integrated photonic circuits. Fluorenone analogues have been demonstrated to be promising candidates as building blocks for assembly of organic NLO materials thanks to their synergistic supramolecular interactions and brilliant optical properties. Here we have studied the polymorphs of a phenylethynyl functionalized fluorenone derivative, and their controlled self-assembly for microstructures with different morphologies. These polymorphic microcrystals exhibit very distinctive NLO properties, highly related to their supramolecular and electronic structures.

Growth, structural, thermal, dielectric and optical studies on HBST crystal: A potential THz emitter

The efficient organic nonlinear optical material 4-hydroxy benzaldehyde-N-methyl 4-stilbazolium tosylate (HBST) was grown from methanol by slope nucleation method combined with slow cooling (SNM-SC) for the first time. The optimum growth conditions based on the cooling rate was further investigated. The single crystal X-ray diffraction (XRD) revealed that the chromophores of HBST crystal make an angle of about 33° with respect to the a-axis, which is close to the optimum of Terahertz (THz)-wave generation and electro-optics applications. NMR and FT-IR spectral studies have been performed to ascertain various functional groups present in the sample. Futhermore, the thermal stability and decomposition stages were analyzed through TG-DTA and DSC techniques. The dielectric constant and dielectric loss of HBST crystal have been studied. Critical optical properties like the absorption coefficient, refractive index, cut-off wavelength and band gap energy were calculated. Photoluminescence (PL) exication studies indicated green emission occured at 507nm. All the results of HBST crystal make it a promising candidate in the fields of optoelectronic and the generation of THz.

Growth and characterization of nonlinear optical crystal – Semicarbazide Picrate

Good-optical-quality single crystals of Semicarbazide Picrate (SP), a new organic charge transfer molecular complex salt, were successfully synthesized and grown by the slow evaporation solution growth technique. The grown crystal is analyzed by various instrumentation techniques. The structure of the grown crystal as determined by single crystal XRD diffraction analysis. The presence of functional groups in the SP crystals is confirmed by FT-IR vibrational analysis. The optical transparency has been studied using UV–vis spectrophotometer. The relative second harmonic generation (SHG) efficiency measurements reveal that the SP crystals is a efficient nonlinear optical (NLO) material having an activity 1.4 times as that of the reference material potassium dihydrogen phosphate. The TG/DTA thermal analyses reveal the purity of the sample and no decomposition is observed up to the melting point. The mechanical properties of the crystal are examined by Vicker's microhardness test. The dielectric permittivity, dielectric loss and AC conductivity of the crystal are measured at various temperatures.

Exploring the potential of boron-doped nanographene as efficient charge transport and nonlinear optical material: A first-principles study

Owing to their excellent electrochemical properties, graphenes found applications in several fields ranging from semiconductors, solar cells, field effect transistors, and nanoscale electronic devices as well as in nonlinear optical (NLO) applications. The structural features, electro-optical, charge transport and nonlinear optical properties of the boron-doped graphene (BG) compound 1 were studied using density functional theory methods The BG compound comprises a central electron deficient site of boron atoms, which can serve as electron acceptor while terminal alkoxy groups as donors leading to powerful donor-π-acceptor (D-π-A) configuration. The experimental crystal structure was successfully reproduced by optimized ground state geometry at PBE0/6-311G* level of theory for isolated molecule. The experimental lattice parameters, geometries, crystal presentation and alignment of molecules in the unit cells as well as their packing orientation of BG compound 1 was also efficiently reproduced by applying periodic boundary conditions (PBC) at PBE level. The comprehensive intramolecular charge transfer (CT) was realized from terminal rings of the HOMO to the electron deficient sites of boron atoms of the LUMO. The nature of BG compound 1 might be more towards hole transport even though its hole reorganization energy is twice than that of the electron one due to the significant higher hole transfer integral values. The superior hole transfer integrals and intrinsic mobility values of the BG compound 1 might lead remarkable hole transport contender as compared to many other organic materials. The narrow band gap, density of states profile, dielectric function, uniform conductivity functions and noteworthy electronic as well as CT properties revealed that the BG compound 1 might be proficient optoelectronic contestant having intermolecular CT as well as intramolecular CT with optimal stability. A comparison of static third-order polarizability <γ> of BG compound 1, as calculated in present investigation, was also performed with some standard NLO molecules as well as graphene nanoflakes. Moreover, longitudinal component γzzzz of parent compound has been found 12 and 4 times larger than those of previously reported open-shell poly aromatic hydrocarbons (PAH). Interestingly, by increasing the donor ability, i.e., introduction of C2H2PhNH2 groups in place of OC4H9 groups (BG compound 3) at terminal positions boosts the <γ> amplitude∼8 times than that of its parent BG compound 1.

Studies on growth and characterization of nicotinium tartrate single crystal: An efficient organic nonlinear optical material

Organic single crystal of nicotinium tartrate (NT), an efficient nonlinear optical (NLO) material for frequency conversion, has been grown at a constant temperature at 40[Formula: see text]C within a period of 20 days by slow evaporation solution technique (SEST). Structural information and lattice dimensions were determined using powder X-ray diffractometer (PXRD) analysis. The functional groups and vibrational frequencies were identified using FTIR spectrum analysis with the range of 4000–450[Formula: see text]cm[Formula: see text]. Mechanical properties of the grown crystal were studied using Vickers microhardness tester. The optical properties of grown crystal were investigated using UV–Vis NIR spectrum analysis and it is confirmed that the crystal has very low absorption in the entire visible region. The dislocations and defects were studied by photoluminescence spectrum. The crystal has single stage melting, which was observed at 180[Formula: see text]C and there was no decomposition before its melting point. Piezoelectric, photoconductivity and chemical etching analysis have also been performed on the grown NT single crystals and the observed results were discussed. Nonlinear optical property of the material was measured using the powder Kurtz–Perry technique.

Synthesis, crystal structure, growth, optical and third order nonlinear optical studies of 8HQ2C5N single crystal - An efficient third-order nonlinear optical material

A neoteric organic third order nonlinear optical material 8-hydroxyquinolinium 2-chloro-5-nitrobenzoate dihydrate (8HQ2C5N) was grown by slow cooling technique using ethanol: water (1:1) mixed solvent. The calculated low value of average etch pit solidity (4.12 × 103 cm−2) indicated that the title crystal contain less defects. From the single crystal X-ray diffraction data, it was endowed that 8HQ2C5N crystal belongs to the monoclinic system with centrosymmetric space group P21/c and the cell parameters values, a = 9.6546 (4) Ǻ, b = 7.1637(3) Ǻ, c = 24.3606 (12) Ǻ, α = γ = 90°, β = 92.458(2)° and volume = 1683.29(13) Ǻ3. The FT-IR and FT-Raman spectrum were used to affirm the functional group of the title compound. The chemical structure of 8HQ2C5N was scrutinized by 13C and 1H NMR spectral analysis and thermal stability through the differential scanning calorimetry study. Using optical studies the lower cut-off wavelength and optical band gap of 8HQ2C5N were found to be 364 nm and 3.17 eV respectively. Using the single oscillator model suggested by Wemple – Didomenico, the oscillator energy (Eo), the dispersion energy (Ed) and static dielectric constant (εo) were estimated. The third-order susceptibility were determined as Im χ(3) = 2.51 × 10−5 esu and Re χ(3) = 4.46 × 10−7 esu. The theoretical third-order nonlinear optical susceptibility χ(3) was calculated and the results were compared with experimental value. Photoluminescence spectrum of 8HQ2C5N crystal showed the yellow emission. The crystal had the single shot laser damage threshold of 5.562 GW/cm2. Microhardness measurement showed that 8HQ2C5N belongs to a soft material category.

Growth, spectral, linear and nonlinear optical characteristics of an efficient semiorganic acentric crystal: L-valinium L-valine chloride

An efficient nonlinear optical semiorganic material L-valinium L-valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P21. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59GW/cm2. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics.

First-principles study of nitrogen-doped nanographene as an efficient charge transport and nonlinear optical material

The prospective of nitrogen doped graphene (NDG) as useful nonlinear optical (NLO) and charge transport materials is explored using first principles methods.

Theoretical investigation on the photoswitchable second-order nonlinear optical properties of a series of B(C6F5)2-coordinated dithienylethene derivatives

The photoswitchable second-order nonlinear optical (NLO) properties of a series of B(C6F5)2-coordinated dithienylethene derivatives have been investigated by density functional theory (DFT) method. The calculations showed that static first hyperpolarizabilities (βtot) of ring-opening and ring-closed systems dramatically increased by introducing the appropriate substituents. Moreover, the calculated βtot values of ring-closed systems were larger than those of the corresponding ring-opening systems, it is mainly attributed to the forming of a larger π-conjugation in the ring-closed systems. The ring-closed form 5c owned the largest βtot values (7361.4 × 10−30 esu), which are 29.8 times larger than that of the corresponding ring-opening form 5o. Besides, to better describe the NLO behaviors of the studied dithienylethene derivatives, the absorption spectra and relative frontier molecular orbitals were calculated by time-dependent density functional theory (TDDFT) method. At last, we also demonstrated that the dispersions have barely influence on the frequency-dependent first hyperpolarizabilities (βtot (ω)) at the low-frequency region ω (0.000–0.030 a.u.). Thus, these theoretical calculations predicted the possible role of the studied systems as effective photoswitchable second-order NLO materials. We hope that this current work will pave the way for further theoretical and experimental design of efficient NLO materials.