Study on nonlinear optical,dielectric and pyroelectric properties of novel organic–inorganic hybrid material

A novel organic and inorganic hybrid material was prepared from a nonlinear, optically active imidazole derivative, 4-(nitrophenyl)-2,4-bis-(4,4′-[N,N-bis-(2-hydroxyethyl)aminophen-yl])imidazole (NPAH4), and metal alkoxide of Ta(V) via sol–gel process. The second-order nonlinear and pyroelectric properties of the hybrid film were investigated in terms of the second harmonic generation (SHG) and pyroelectric coefficient measurement. The SHG coefficient d₃₃ was found to be 28.6 pm/V at the fundamental wavelength of 1064 nm and the pyroelectric coefficient P was found to be 1.6×10⁻⁶ C/cm² K.     

Synthesis and non linear optical properties of new inorganic–organic hybrid material: 4-Benzylpiperidinium sulfate monohydrate

Single crystals of 4-benzyl-piperidine sulfate monohydrate were grown by slow evaporation method at room temperature. The synthesized compound was characterized by means of single-crystal X-ray diffraction, FT-IR and Raman spectroscopy, UV–visible and photoluminescence studies. The title compound crystallises at room temperature in the non centrosymmetric space group P2₁2₁2₁.The recorded UV–visible spectrum show good transparency in the visible region and indicates a non-zero value of the first Hyperpolarizability. Photoluminescence spectrum shows a broad and intense band at 440 nm and indicates that the crystal emits blue fluorescence. We also report DFT calculations of the electric dipole moments (μ), Polarizability (α), the static first Hyperpolarizability (β) and HOMO–LUMO analysis of the title compound was theoretically investigated by GAUSSIAN 03 package. The calculated static first Hyperpolarizability is equal to 6.4022 × 10⁻³¹ esu. The results show that 4-benzyl-piperidine sulfate monohydrate crystal might have important non linear optical behavior and can be a potential non linear optical material of interest.     

Morphology and thermal properties of organic–inorganic hybrid material involving monofunctional-anhydride POSS and epoxy resin

Monofunctional-anhydride polyhedral oligomeric silsesquioxane (i-C₄H₉)₇Si₈O₁₂OSi(CH₃)₂(C₈H₉O₃) (AH-POSS) was synthesized and characterized by FTIR, NMR, element analysis. Then AH-POSS was incorporated into epoxy system either pre-reacted or non-reacted using hexahydrophthalic anhydride (HHPA) as curing agent. Pre-reacted system hybrid materials were obtained by two-step preparation. First, AH-POSS reacted with part of diglycidyl ether of bisphenol A (DGEBA) to form AH-POSS-epoxy precursor in DGEBA, then cured with HHPA. Non-reacted POSS/epoxy hybrid materials were prepared by directly mixing AH-POSS, HHPA and DGEBA together and cured afterwards. The GPC and FTIR spectra suggested successful bonding of AH-POSS and epoxy resin. Morphologies of hybrid materials were characterized by SEM and TEM. Non-reacted system led to a dispersion of spherical particles with sizes in the range of micrometers. For pre-reacted system, polymerization-induced phase separation took place with POSS content lower than 30 wt% and also some “vesicle” structure was formed after curing. A typical macro-phase separation happened with POSS content up to 40 wt% before and after curing. The glass transition temperatures (T_g's) and the storage modulus were measured by dynamic mechanical analysis (DMA). T_g's and modulus displayed irregularly decrease. The initial thermal decomposition temperatures (T_d's) characterized by TGA were also irregularly decreasing for both systems. However, they were higher than those of epoxy composites when using amine as the curing agent.     

Design and synthesis of inorganic–organic hybrid microstructures

Vanadium oxide–polypyrrole (V₂O₅–PPy) hybrid aerogels were prepared using three different strategies. These approaches were focused on either sequential or consecutive polymerization of the inorganic and organic networks. The hybrid microstructure differed greatly depending on which synthesis approach was used. Microcomposite aerogels were synthesized by encapsulating a dispersion of preformed PPy in a V₂O₅ gel. In the second approach, pyrrole was polymerized and doped within the pore volume of a preformed V₂O₅ gel. The hybrid microstructure of these materials was nanometer scaled but inhomogeneous. When the inorganic and organic precursors were allowed to polymerize simultaneously, the resulting gels exhibited a nanometer-scaled microstructure with a homogeneous distribution of the PPy and the V₂O₅. Through this route, a suitable microstructure and composition for a lithium secondary battery cathode were obtained. Undoped material with a composition of [PPy]_0.8V₂O₅ exhibited a lithium intercalation capacity comparable to that of V₂O₅ aerogel. For the full benefit of the PPy phase to be achieved, a suitable doping procedure is still required to oxidize the PPy into its high conductivity state while preserving the inorganic structure.     

Adsorptive properties of sol–gel derived hybrid organic/inorganic coatings

Hybrid organic-inorganic sol–gel derived coatings have been prepared by dip coating on glass substrates from alcoholic solutions of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), 3-aminopropyltriethoxysilane (APTES), 3-glycidoxypropyltrimethoxysilane (GPTMS) and phenyltriethoxysilane (PhTES). The hybrid materials have been fully characterized by means of solid state NMR spectroscopy and X-ray diffraction. The degree of cross-linking and the extent of interaction between silica and silsesquioxane phases appear dependent on the ratio between TEOS and organotrialkoxysilane and on the chemical features of the organic function linked to silicon, and influence the sorption ability towards aromatic compounds of hybrid films. The hybrid coatings have been put into an optical-grade quartz chamber placed into a UV–VIS–NIR spectrophotometer and the organic compounds have been allowed flowing through the chamber recording of molecule absorption spectra vs. time. Absorbance curves vs. time have also been collected at a fixed wavelength for different molecule-coating couples and simple kinetic models have been used for comparing the adsorption capability of the different films, which has been related to the chemical interactions between molecules and coatings.     

Structural,optical, electrical properties of new hybrid organic–inorganic NLO single crystal: bis(1H-benzotriazole) hexaaqua-zinc bis(sulfate) tetrahydrate (BZS)

A new hybrid organic–inorganic nonlinear (NLO) single crystal, Bis(1H-benzotriazole) hexaaqua-zinc bis(sulfate) tetrahydrate (BZS), has been successfully synthesized and the single crystals were grown by slow evaporation solution growth technique (SESG) using Millipore water as a solvent. The structure of the BZS crystal was solved and refined by single-crystal X-ray diffraction and demonstrates that the grown crystals belong to a triclinic system with the space group P-1. The asymmetric part of the titled compound contains isolated organic cation (C₆H₆N₃)₂, metallic cation [Zn(H₂O)₆]²⁺, sulfate anion (SO₄)^2? and free H₂O molecules. The interplay between the wide number of intermolecular interaction such as O–H···O, N–H···O, C–H···O and π–π stacking interactions were discussed. The optical transmittance spectrum shows that the crystal is excellent transmittance in the entire Vis–NIR region with the cutoff wavelength at 345 nm. The presences of expected functional groups were identified by Fourier transform infrared spectroscopy. The dielectric measurements were carried out at different temperature in the frequency range 100 Hz–5MHz. Furthermore, the studies of its third-order NLO properties using a Z-scan technique demonstrate that the BZS crystal possesses a strong reverse saturable absorption (RSA) and the self-focusing (SF) nature with large second order hyperpolarizability (γ?=?6.24?×?10^?34 esu). All the results indicate that BZS crystal might be the potential candidate for the third-order NLO applications.     

Keggin type inorganic–organic hybrid material containing Mn(II) monosubstituted phosphotungstate and S-(+)-sec-butyl amine: Synthesis and characterization

A new inorganic–organic POM-based hybrid material comprising Keggin type mono manganese substituted phosphotungstate and enantiopure S-(+)-sec-butyl amine was synthesized in an aqueous media by simple ligand substitution method. The synthesized hybrid material was systematically characterized in solid as well as solution by various physicochemical techniques such as elemental analysis, TGA, UV–vis, FT-IR, ESR and multinuclear solution NMR (³¹P, ¹H, ¹³C). The presence of chirality in the synthesized material was confirmed by CD spectroscopy and polarimeter. The above study reveals the attachment of S-(+)-sec-butyl amine to Keggin type mono manganese substituted phosphotungstate through N → Mn bond. It also indicates the retainment of Keggin unit and presence of chirality in the synthesized material. An attempt was made to use the synthesized material as a heterogeneous catalyst for carrying out aerobic asymmetric oxidation of styrene using molecular oxygen. The catalyst shows the potential of being used as a stable recyclable catalytic material after simple regeneration without significant loss in conversion.     

Preparation and properties of an organic–inorganic hybrid materials based on fluorinated block copolymer

The block copolymers of poly 2,2,3,4,4,4-hexafluorobutyl methacrylate-block-poly[3-(trimethyoxysilyl)propyl methacrylate] (PHFMA-b-PTMSPMA) were synthesized via atom transfer radical polymerization and used for the preparation of organic/inorganic hybrid materials by the sol–gel approach. The polymers were characterized by gel permeation chromatography, Fourier transform infrared and ¹H nuclear magnetic resonance. The properties of the hybrid materials were investigated by Scanning electronic microscopy, contact angle, Scotch tape test, transmittances measurement, differential scanning calorimetry, and thermogravimetric analysis. The results were as follows: First, the hybrid materials had surface roughness, good hydrophobicity (>95° in contact angle with water), and could improve the contact angle of glass from 65.2° to 99.9° (the content of TMSPMA was 4.9 wt% in its polymer). Second, the adhesion of the hybrid materials to glass were enhanced by incorporating TMSPMA. Third, light transmittances of all the hybrid materials were above 90% in the visible range. Finally, the thermal stability of the hybrid materials were enhanced by incorporating silica moiety.     

Morphological investigation of ternary and semicrystalline organic–inorganic hybrid nanocomposite

Journal of Materials Science - Organic–inorganic (O–I) hybrid nanocomposites have already been widely investigated in the optoelectronic industry and are emerging in the biomedical...     

Direct deposition of inorganic–organic hybrid semiconductors and their template-assisted microstructures

A straight-forward method is developed to deposit a new class of self-organized inorganic–organic (IO) hybrid, (C₁₂H₂₅NH₃)₂PbI₄. These IO hybrid structures are stacked-up as natural multiple quantum well structures and exhibit strong room-temperature exciton emission and other multifunctional features. Here it is successfully demonstrated that these materials can be directly carved into 2D photonic structures from the inexpensive template-assisted electrochemical deposition followed by solution processing. The applicability of this method for many such varieties of IO-hybrids is also explored. By appropriately controlling the deposition conditions and the self-assembly templates, target structures are developed for new-generation low-cost photonic devices.     

Enhanced visible-light-driven photocatalytic and dielectric properties of inorganic–organic hybrid (NiO-g-C3N4) nanocomposite for degradation of rhodamine blue

In this work, NiO NP’s was synthesized by the hydrothermal method and g-C₃N₄ nanosheets prepared via thermal treatment method, then NiO/g-C₃N₄ (80:20 wt%) was successfully achieved by a simple mixing method. The optimized NiO/g-C₃N₄ hybrid nanocomposite was acting as an efficient photocatalyst for degradation of rhodamine blue (RhB) under visible light irradiation. As prepared pristine (NiO and g-C₃N₄) and inorganic–organic hybrid nanocomposite (NiO/g-C₃N₄) materials were characterized by various spectral techniques. From XRD and TEM results, the NiO nanoparticles before and after loading on g-C₃N₄ surface retained the crystalline phase(fcc) and spherical structure, indicating the synthesis strategy is promising which does not alter its composition and morphology. The adsorption edge of NiO/g-C₃N₄ was shifted towards lower energy region when compared with pure NiO and g-C₃N₄ alone reflects that the resulting nanocomposite has larger adsorption efficiency under visible light and thus increases the charge separation efficiency during degradation process. The percentage of degration of RhB for NiO, g-C₃N₄ and NiO/g-C₃N₄ hybrid is calculated to be 81, 89 and 94% indicates the effective degradation illuminated under visible light. The enhanced photocatalytic activity of NiO/g-C₃N₄ photocatalyst probably recognized for the successful interfacial charge separation between NiO and g-C₃N₄ thus avoids recombination of photoexcited electron–hole pair.

     

Structural,optical and photoluminescence properties of hybrid metal–organic halide perovskite thin films prepared by a single step solution method

We report an inexpensive single step solution method to produce hybrid organic–inorganic lead iodide perovskite thin films for their application to photovoltaic devices. Using PbI₂ and CH₃NH₃Cl (MACl) as precursors for this single step solution method, CH₃NH₃PbI₃ (MAPbI₃) mixed with a small amount of CH₃NH₃PbCl₃ (MAPbCl₃) can be obtained after an annealing process at temperatures around 100 °C for 2 h. The synthesis of the obtained hybrid halide perovskites yields uniform films with reproducible properties. The films were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV–Vis spectroscopy and photoluminescence (PL). The XRD measurements confirm the presence of cubic CH₃NH₃PbCl₃ perovskite crystallites mixed with tetragonal perovskite crystallites of CH₃NH₃PbI₃ in the films with crystallite sizes for the latter around 34.8 nm. Texture analysis indicates that these crystallites have a preferential orientation at the (002) plane. Raman characterization shows the presence of PbI₂ and MAPbI₃ vibrational modes. Photoluminescence at room temperature shows an intense emission peak at 1.61 eV associated to the excitonic transition energy of the hybrid lead iodide perovskites. From optical transmittance measurements we notice that the absorption edge is around 1.61 eV, in good agreement with the photoluminescence results. This effective band gap energy is associated with a small amount of CH₃NH₃PbCl₃ (around 6%) mixed with CH₃NH₃PbI₃ crystallites. We are in the process of optimizing the photoelectronic and structural properties of the films for their application as inexpensive absorbing layers in solar cells.     

Structural and optical properties of In doped Se–Te phase-change thin films: A material for optical data storage

Se_75−xTe₂₅In_x (x = 0, 3, 6, & 9) bulk glasses were obtained by melt quench technique. Thin films of thickness 400 nm were prepared by thermal evaporation technique at a base pressure of 10⁻⁶ Torr onto well cleaned glass substrate. a-Se_75−xTe₂₅In_x thin films were annealed at different temperatures for 2 h. As prepared and annealed films were characterized by X-ray diffraction and UV–Vis spectroscopy. The X-ray diffraction results show that the as-prepared films are of amorphous nature while it shows some poly-crystalline structure in amorphous phases after annealing. The optical absorption spectra of these films were measured in the wavelength range 400–1100 nm in order to derive the extinction and absorption coefficient of these films. It was found that the mechanism of optical absorption follows the rule of allowed non-direct transition. The optical band gap of as prepared and annealed films as a function of photon energy has been studied. The optical band gap is found to decrease with increase in annealing temperature in the present glassy system. It happens due to crystallization of amorphous films. The decrease in optical band gap due to annealing is an interesting behavior for a material to be used in optical storage. The optical band gap has been observed to decrease with the increase of In content in Se–Te glassy system.     

Structural characterizations and optical properties of new Li–Sr–Nb-phosphate glasses

A new Li₂O–SrO–Nb₂O₅–P₂O₅ glass system was prepared by a high-temperature alumina crucible, and structural characterization and optical properties were investigated. Proper content of Li₂O and Nb₂O₅ was employed to replace partial SrO and P₂O₅ to improve the optical properties. It was observed that the enhancement of the refractive index from 1.75 to 1.85 is mainly due to the Nb₂O₅ content. An addition of Li₂O significantly increases the optical transmittance; optical transparency can be enhanced from 60% to higher than 85% in the UV–visible region with addition of 20–40 mol% Li₂O species. However, optical transmittance is monotonically decreased from about 90% to 80% under 10–30 mol% Nb₂O₅ addition. The 40P₂O₅–20Nb₂O₅–20SrO–20Li₂O glasses demonstrate the optimum refractive index (n > 1.75) and high optical transparency (>80%) in the UV–visible region.     

Manufacture of photovoltaic cells with hybrid organic–inorganic bulk heterojunction

The aim of this paper is to present the influences of material composition and production conditions of the photovoltaic cells on its parameters as well as the active layer properties. The layers were made of organic compounds: metal phthalocyanine/perylene derivatives. In addition, the effects of TiO₂ and SiO₂ nanoadditives were investigated. The materials used are selected so as to allow P–N junction creation. Deposition technique allows at simultaneous applying the materials leads to obtaining homogeneous dispersion of one material in the other, which determines the formation of bulk P–N junctions. Research includes the estimate of share of individual components in the active layer, then determination of the morphology of surface and optical properties of the same layer and its implementation in photovoltaic structures. The structural researches and morphology of surface investigation were made using transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The optical properties were researched with the use of UV–Visible spectroscope. The parameters of cells have been determined on the basis of current–voltage characteristics. The work undertaken within the framework of article allowed to linking properties of active layers with the parameters of the same cells.     

Isomerization and optical bistability of DR1 doped organic–inorganic sol–gel thin film

To investigate the isomerization process of the disperse red 1 (DR1) doped TiO₂/ormosil thin film, both the photo-isomerization and the thermal isomerization of the thin films were observed as a change of the absorption spectrum. Under a real-time heat treatment, the change of the linear refractive index shows a thermal stable working temperature range below T_g. The optical bistability (OB) effect of the DR1 doped thin films based on different matrices was studied and measured at a wavelength of 532 nm. Results indicate that the TiO₂/ormosils based thin film presents a better OB-gain than that of the poly (methyl methacrylate) (PMMA) based thin film due to its more rigid network structure. Moreover, it is also noted that higher titanium content is helpful for enhancing the OB-gain of the as-prepared hybrid thin films.     

Compressive properties of a new metal–polymer hybrid material

Compressive properties of a new hybrid material, fabricated through filling of an aluminum foam with a thermoplastic polymer, are investigated. Static (0.01 s⁻¹) and dynamic (100 s⁻¹) compression testing has been carried out to study the behavior of the hybrid material in comparison with its parent foam and polymer materials. Considering the behavior of metal foams, the point on a compressive stress–strain curve corresponding to the minimum cushion factor is defined as the “densification” point. The analysis of the stress–strain curves provides insight into the load carrying and energy absorption characteristics of the hybrid material. At both strain rates, the hybrid is found to carry higher stresses and absorb more energy at “densification” than the foam or polymer.     

Preparation and performance of organic–inorganic halide perovskites

Layered organic–inorganic perovskites have potential application in solar cells because of their unique electrical and optical properties. These materials can also overcome the instability of organic sensitizers and the disorder of metal oxides. A preliminary study on the preparation of organic–inorganic halide perovskites (CH₃NH₃PbI _x Cl_3?x ) was conducted in this paper. The synthesis temperature and thermal stability in air were analyzed by thermogravimetric analysis and differential scanning calorimetry. The structure and morphology of the products were investigated by X-ray diffraction and scanning electron microscopy. UV–visible spectroscopy revealed that the material had good absorption within the range of 350–750 nm and can be used as the active light-absorbing layer of solar cells. Hybrid solar cells of FTO/TiO₂–CH₃NH₃PbI _x Cl_3?x /Spiro-MeOTAD/Ag were found to have a high fill factor of 0.5 but low power conversion efficiency of 0.28 %.     

Development of strong and bioactive calcium phosphate cement as a light-cure organic–inorganic hybrid

In this research, light cured calcium phosphate cements (LCCPCs) were developed by mixing a powder phase (P) consisting of tetracalcium phosphate and dicalcium phosphate and a photo-curable resin phase (L), mixture of hydroxyethylmethacrylate (HEMA)/poly acrylic-maleic acid at various P/L ratios of 2.0, 2.4 and 2.8?g/mL. Mechanical strength, phase composition, chemical groups and microstructure of the cured cements were evaluated at pre-set times, i.e. before and after soaking in simulated body fluid (SBF). The proliferation of Rat-derived osteoblastic cells onto the LCCPCs as well as cytotoxicity of cement extracts were determined by cell counting and 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H-tetrazolium bromide assay after different culture times. It was estimated from Fourier transforming infrared spectra of cured cements that the setting process is ruled by polymerization of HEMA monomers as well as formation of calcium poly-carboxylate salts. Microstructure of the cured cements consisted of calcium phosphate particles surrounded by polymerized resin phase. Formation of nano-sized needlelike calcium phosphate phase on surfaces of cements with P/L ratios of 2.4 and 2.8?g/mL was confirmed by scanning electron microscope images and X-ray diffractometry (XRD) of the cured specimen soaked in SBF for 21?days. Also, XRD patterns revealed that the formed calcium phosphate layer was apatite phase in a poor crystalline form. Biodegradation of the cements was confirmed by weight loss, change in molecular weight of polymer and morphology of the samples after different soaking periods. The maximum compressive strength of LCCPCs governed by resin polymerization and calcium polycarboxylate salts formation was about 80?MPa for cement with P/L ratio of 2.8?g/mL, after incubation for 24?h. The strength of all cements decreased by decreasing P/L ratio as well as increasing soaking time. The preliminary cell studies revealed that LCCPCs could support proliferation of osteoblasts cultured on their surfaces and no cytotoxic effect was observed for the extracts of them.