Preparation of poly(acrylic)/SiO2/EuL3 x 2H2O, hybrid thin films from monodispersed colloidal silica

In this study, poly(acrylic)/SiO2/EuL3 x 2H2O hybrid thin films were prepared from various acrylic monomers (MMA and EDMA/TMPTA), lanthanide metal complexes (EuL3 x 2H2O, L = pyridine carboxylic acid), and monodispersed colloidal silica with a coupling agent, 3-(trimethoxysilyl)propyl methacrylate (MSMA). It is a combination of the sol-gel reaction, thermal polymerization, and spin coating. The silica content in the hybrid thin films is fixed at 20 wt%, and the EuL3 x 2H2O content is varied from 0.01 g to 0.07 g. FTIR and EA analysis confirms the chemical structure of the prepared EuL3 x 2H2O and poly(acrylic)/SiO2/EuL3 x 2H2O hybrid thin films. UV-Vis spectra and n&k analysis shows that the hybrid thin film has good transparency in visible light. The refractive index of hybrid thin films can be effectively controlled through the EuL3 x 2H2O content. The PL spectra shows that the strongest emission peak occurs at 615 nm and the emission intensity increases to the peak maximum at an EuL3 x 2H2O content of 0.05 g. Both TGA and PL analysis show that the prepared hybrid thin films from the crosslinked acrylic polymer moiety have much better film uniformity, thermal stability, and fluorescence properties. The TEM diagram shows that the MSMA/SiO2/EuL3 x 2H2O particles with a size 15-20 nm are well dispersed in the reaction solution. The SEM diagram shows that the particle distribution in the prepared hybrid thin films is uniform and no phase separation is observed. Finally, AFM analysis indicates that the prepared hybrid thin films have an excellent surface planarity.     

Approach to a block polymer precursor from poly(3-hexylthiophene) nitroxide-mediated in situ polymerization for stabilization of poly(3-hexylthiophene)/ZnO hybrid solar cells

A cross-linked block copolymer poly(3-hexylthiophene)-b-poly(zinc dimethacrylate) (P3HT-b-PZn(MA)₂), which acted as precursor for the preparation of poly(3-hexylthiophene)/ZnO (P3HT/ZnO) hybrid film by in-situ hydrolysis, was rationally designed and synthesized via nitroxide-mediated in-situ polymerization of zinc methacrylate (Zn(MA)₂) using poly(3-hexylthiophene) alkoxyamine (P3HT-TIPNO) as macroinitiator for the purpose of stabilizing the P3HT/ZnO hybrid solar cells. The cross-linking was confirmed by the insolubility of the film in organic solvents and Fourier-transform infrared experiment. With the function of the cross-linked template, the diffusion of ZnO nanoparticles prepared by in-situ hydrolysis could be lowered to suppress the formation of large aggregations, which favored the formation of a better and more stable interpenetrating network and provided more heterojunction interfaces for exciton dissociation. As a result, the inverted device based on cross-linked P3HT/ZnO hybrid film obtained by in situ hydrolyzing P3HT-b-PZn(MA)₂ block copolymer yielded a power conversion efficiency of 0.45% under AM 1.5G illumination from a calibrated solar simulator with an intensity of 100 mW/cm², and the deterioration of the photoconversion performance was suppressed in the hybrid solar cells with the cross-linked P3HT/ZnO compared to cells with non-cross-linked P3HT/ZnO obtained by in situ hydrolyzing P3HT-TIPNO/Zn(MA)₂ blend film.     

Synthesis and characterization of electrochromic poly(amide–imide)s bearing methoxy-substituted triphenylamine units

New poly(amide–imide)s (PAIs) 3a–d and 3′a–d with methoxy-substituted triphenylamine (TPA) units were prepared by the direct polycondensation from various imide ring-preformed dicarboxylic acids 2a–d with 4,4′-diamino-2″,4″-dimethoxytriphenylamine (1) and 4,4′-diamino-4″-methoxytriphenylamine (1′), respectively, using triphenyl phosphite and pyridine as condensing agents. For the comparative study, the referenced PAIs 3″a–d without methoxy substituents on the TPA unit were also prepared from 2a–d with 4,4′-diaminotriphenylamine (1″). All the polymers were readily soluble in many organic solvents and could be solution-cast into tough and flexible polymer films. The glass-transition temperatures (T_gs) of these PAIs ranged from 196 to 298 °C and the 10% weight-loss temperatures were in excess of 445 °C in nitrogen. Cyclic voltammograms of the PAI films cast onto the indium–tin oxide (ITO)-coated glass substrate exhibit one reversible oxidation redox couples at 0.73–0.89 V vs. Ag/AgCl in an electrolyte/acetonitrile solution. The polymer films revealed good electrochemical and electrochromic stability, with coloration change from a pale yellow neutral form to a green oxidized form. After over 100 redox cycles, the polymer films still exhibited good redox and electrochromic reversibility. The 3 and 3′ series PAIs exhibited enhanced redox-stability and electrochromic performance as compared to the parent 3″ analogs without methoxy substituents on the TPA unit.     

Multilayer films consisted of azulene-based dye molecules and polyelectrolyte: Preparation, characterization and photoluminescent property

Ultrathin multilayer films of two azulene-based (Az-based) dye molecules (Az), 3-methylazulene-1-carboxylic acid hydrazide (Az-1) and 5-(4-phenylamine)-2-(3-methylazulene-1-yl)-1,3,4-oxadiazoles (Az-2), and poly(sodium 4-styrenesulfonate) (PSS) have been prepared by layer-by-layer self-assembly and characterized by UV-vis spectroscopy, fluorescence spectroscopy, small-angle X-ray reflectivity measurements and atomic force microscopy (AFM) imaging. UV-vis spectra show that the characteristic absorbance values of the multilayer films increase almost linearly with the number of PSS/Az bilayers, suggesting that the deposition process is regular and highly reproducible from layer to layer. Average thicknesses for the PSS/Az-1 and PSS/Az-2 bilayers of the multilayer films are ca. 0.9 and 1.4 nm, respectively. AFM images provide the surface morphology of the PSS/Az films, indicating that the film surface is relatively uniform and smooth. The occurrence of photoluminescent activity conforms the potential for creating luminescent multilayer films with Az-based dye molecules.     

Near-infrared luminescent polymer thin films containing Yb(III) complex and photosensitized dye

Polymethylmethacrylate (PMMA) thin films containing Yb(pms)₃(H₂O)₈ (pms: bis(perfluoromethanesulfonyl)imide) and dipyridophenazine with DMSO and DMSO-d₆ were fabricated on the glass substrates. The films show photosensitized near-IR luminescence under UV light irradiation of 370 nm in wavelength. The emission quantum yields of Yb(III) complex in PMMA (film 1), PMMA containing DMSO (film 2), and PMMA containing DMSO-d₆ (film 3) thin films are 0.18, 0.26, and 0.26%, respectively. The emission quantum yields of films 1 and 2 were considerably enhanced after the annealing at 80 °C.     

Role of chain length and spacers in the organization of long chain Schiff base compounds at air/water and solid/liquid interfaces

Langmuir films of long chain Schiff base compounds: N-(4-fluorobenzylidene)hexadecanamine (compound 1), N-(4-fluorobenzylidene)octadecanamine (compound 2) and 4-{[(4-fluorobenzylidene)amino]methyl}-N-hexadecylaniline (compound 3) have been studied at air/water interface using the characteristic surface pressure-molecular area (π-A) and surface potential-molecular area (ΔV-A) isotherms. Photoelastic modulated Fourier transform infrared spectroscopy has been used to analyze the films of the three compounds at air/water interface. The Langmuir-Blodgett films of these compounds have been characterized using X-ray diffraction that shows layered structures, with interlayer distances of up to 4.4 nm for compound 3. The results show that the layer-to-layer distance can be easily and rationally designed by choosing alkyl chains of different lengths and spacer. Compound 3 packs in an interdigitated bilayer structure with longer lamellar spacing whereas compounds 1 and 2 show a noninterdigitated monolayer structure. Atomistic model calculations have been carried out on the three compounds and the dipole moment values obtained agreed well with the experimental results of surface potential in Langmuir films. Among the three compounds, compound 3 forms stable vesicles spontaneously at room temperature.     

Optical and morphological characterization by atomic force microscopy of luminescent 2-styrylpyridine derivative compounds with Poly(N-vinylcarbazole) films

The present work addresses the optical and morphological properties of organic films based on low molecular weight dyes styrylpyridine derivatives 2-styrylpyridine (A), 4-chlorophenyl-2-vinylpyridine (B) and 4-fluorophenyl-2-vinylpyridine (C), embedded in a polymeric matrix poly(N-vinylcarbazole) (PVK). The films were prepared by a spin-coating technique from solutions with dye:PVK ratios of 0.25:1, 0.5:1 and 1:1. Solvents were chloroform and toluene. The molar absorption coefficient (ε) spectra for a dye:PVK mixture in solution were a combination of the absorptions of both components separately, but for the deposited films, the shape of the spectrum showed that the poly(N-vinylcarbazole) absorption dominated. However, when the same films were dissolved again in CHCl₃, their spectra showed an absorption shape similar to that of the solution mixture before the deposition. Solution viscosity measurements were carried out with an Ubbelohde glass capillary viscometer to corroborate the results that showed a better mixture of the dye with the host in chloroform. The morphology of the prepared films was analyzed by atomic force microscopy and exhibited a solvent effect, with a pinhole-free, smooth surface when toluene was used and a wavy surface with chloroform. The ratio dye:matrix was the principal parameter for obtaining optical quality films; for 0.25:1 and 0.5:1 ratios, the films were of good quality, but for 1:1, the dye was expelled from the PVK and a crystallization was present over the surface of the films. Film thickness was also measured and films deposited from toluene solutions gave an average thickness of 54 nm while films from chloroform solutions had an average thickness greater than 160 nm that increased depending on chromophore concentration.     

Photoinduced charge transfer through films containing poly(hexylthiophene), phthalocyanine, and porphyrin-fullerene layers

Efficient photoinduced interlayer electron transfer from a phthalocyanine derivative, ZnPH4, to porphyrin cation of a porphyrin-fullerene donor-acceptor dyad was demonstrated by using time-resolved photovoltage technique. Multicomponent thin films with desired layer arrangements were constructed by the Langmuir-Blodgett and spin-coating methods in order to study charge transfer in solid state. As a contradiction to the photovoltage experiments, the dyad monolayer in the film structure did not enhance the current amplitude in electrochemical photocurrent measurements. This is associated with a weak electronic interaction between fullerene and aqueous electrolyte, reducing the photocurrent generation. The use of poly(3-hexylthiophene) as a hole conducting layer was shown to improve photocurrent yield of the device by forming efficient heterojunction together with the ZnPH4 layer.     

Aragonite Nanorods in Calcium Carbonate/Polymer Hybrids Formed through Self‐Organization Processes from Amorphous Calcium Carbonate Solution

Nanostructured inorganic/polymer hybrid thin films comprising aragonite nanorods derived from aqueous suspensions of amorphous calcium carbonate (ACC) are prepared. For the formation of calcium carbonate (CaCO₃)/polymer hybrids, spincoated and annealed films of poly(vinyl alcohol) (PVA) that function as polymer matrices are soaked in aqueous colloidal solutions dispersing ACC stabilized by poly(acrylic acid) (PAA). In the initial stage, calcite thin films form on the surface. Subsequently, aragonite crystals start to form inside the PVA matrix that contains PVA crystallites which induce aragonite nucleation. Nanostructured hybrids composed of calcite thin films consisting of nanoparticles and assembled aragonite nanorods are formed in the matrices of PVA.     

High-permittivity and low-loss dielectric tunable pyrochlore thin films deposited by radio frequency magnetron sputtering from a lead zinc niobate target

Since Bi₂O₃-ZnO-Nb₂O₅ (BZN) pyrochlore thin films have been introduced as a tunable dielectric, the substitution of Bi with Pb could be a reasonable choice. The PbO-ZnO-Nb₂O₅ (PZN) cubic pyrochlore thin films were produced by radio frequency sputtering, and their dielectric properties, in terms of tunability, were measured. Up to 33.4% of tunability and comparable K factors with BZN films were obtained. The effects of film crystallization, along with substrate heating and post-annealing on the dielectric properties, were similar to those of BZN. However, strong texturing developed in the PbO-ZnO-Nb₂O₅ (PZN) films deposited at a high substrate temperature, which caused degradation of the loss tangent and K factor.     

Cationic triblock copolymer micelles deliver anionic spacer chains substituted aluminum phthalocyanine for enhancement intracellular photodynamic efficacy

A novel spacer chains substituted aluminum phthalocyanine (Pc), naming tetra-carboxylaminohexanoicsulfonyl aluminium phthalocyanine 4 was synthesized. Its structure was characterized by elemental analysis, IR, ¹H NMR and MS. Polyion complex micelle (PIC) between the 4 and amphiphilic triblock copolymer poly(L-lysin)-block-poly(ethylene glycol)-block-poly(L-lysin) (PLL-b-PEG-b-PLL) was formed via an electrostatic interaction between the positively charged poly(L-lysin)(PLL) segment and negatively charged periphery of the 4. Dynamic light scattering (DLS) and atom force microscopy (AFM) image showed that 4-loaded PIC formed a spherical nanocarrier micelle with approximately 85 nm in diameter. The fluorescence intensity and lifetime of 4-loaded PIC were significantly enhanced by the incorporation 4 into PIC nanocarrier. The time-dependent intracellular uptake amount and in vitro photodynamic photocytotoxicity of the 4 within the nanocarrier were drastically improved compared with the free 4.     

Chemosensory rhodamine-immobilized mesoporous silica material for extracting mercury ion in water with improved sensitivity

Mesoporous silica material, SBA-15, is an excellent support for constructing fluorescent surface sensor. In this paper, we reported a three-step surface reaction involved strategy to construct efficient fluorescent surface sensor for mercury ion by clicking rhodamine fluoroionophores onto APES-functionalized SBA-15, which is fully characterized by IR spectra, TGA analysis, elemental analysis, nitrogen adsorption experiment and TEM. Our experimental results indicated that such a strategy exhibits an obviously higher loading efficiency within SBA-15 than a previously reported strategy. The Hg²⁺ extracting efficiency for SBAIR was found to be enhanced (ca. 89%). In addition to the high selectivity, the current chemosensor shows improved sensitivity and can respond to Hg²⁺ as low as ppb level (1.0 × 10⁻⁸ M, 2 ppb) in water.     

Synthesis, photophysical, electrochemical and thermal studies on carbazole-based acceptor molecules for heterojunction solar cell

Five small molecules, 3-tricyanovinyl-N-alkylcarbazoles (6-10) have been synthesized in a cost-effective way and characterized. The molecules have high thermal stability, good thin film formation ability and are also air stable. The change of alkyl chain length altered the aggregation pattern in the thin film. Their photophysical and electrochemical studies promise a compatible highest occupied molecular orbital - lowest unoccupied molecular orbital energy level to be potentially useful as good electron acceptor materials in heterojunction solar cell in combination with copper(II)phthalocyanine or poly-3-hexylthiophene (P3HT) as donor. Significant photoluminescence quenching of P3HT in P3HT:6-10 blends were observed.     

Deposition of rod-shaped antimony sulfide thin films from single-source antimony thiosemicarbazone precursors

Antimony sulfide thin films were deposited on glass substrates by aerosol assisted chemical vapour deposition technique using single source precursors, namely, antimony(III) thiosemicarbazones, SbCl₃(L) (L = thiosemicarbazones of thiophene-2-carboxaldehyde (1) and cinnamaldehyde (2)). The deposited films were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and UV-visible spectroscopy in order to identify their phases, morphologies, compositions and optical properties respectively. These characterizations revealed that the films were comprised of rod-shaped particles of orthorhombic stibnite (Sb₂S₃) with a Sb:S stoichiometry of ∼ 1:1.3. The calculated optical band gap from UV-vis absorption spectrum is found to be 3.48 eV.     

Synthesis and properties of polycyclic quinones condensed with 1,6-methano[10]annulene

Two types of polycyclic quinones condensed with 1,6-methano[10]annulenes as type A: 1,6-methanonaphtho[2,3-c][10]annulene-7,12-dione 5a, and type B: 1,6-methanonaphtho[2,3-c][10]annulene-5,14-dione 18, bis(1,6-methano[10]annuleno[3,4-b; 3,4-g])anthracene-10,21-dione 20, 1,6-methanoanthraceno[2,3-c][10]annulene-5,16-dione 22, 1,6-methanotetraceno[2,3-c][10]annulene-6,17-dione 23, and 1,6-methano phenanthreno[2,3-c][10]annulene-5,6-dione 24 have been synthesized. The acene derivative 6 corresponding to that of 5a was synthesized by the reduction of quinone 5a. The physical, spectral, and chemical properties of these new compounds have been investigated.     

Optical constants of platinum octaethyl porphyrin in single-layer organic light emitting diode studied by spectroscopic ellipsometry

We studied the optical properties of platinum octaethyl porphyrin (PtOEP) emitting layer in single-layer organic light emitting diode (OLED) device and in thin film grown on quartz plate using a phase modulated spectroscopic ellipsometry. Spectra of optical constants (refractive index n and extinction coefficient k) were obtained for PtOEP in the visible-ultraviolet spectral range. Difference was observed in the n and k spectra between the thin film evaporated on quartz plate and the encapsulated OLED. Additionally, difference was found between the layer thickness estimated by quartz oscillator and thickness estimated from the ellipsometry measurement. Discussion is given on contamination by oxygen and moisture in the unsealed thin film.     

Efficient bulk heterojunction solar cells based on D–A copolymers as electron donors and PC70BM as electron acceptor

Two low band gap conjugated polymers P1 (alternating phenylenevinylene containing thiophene and pyrrole rings) and P2 (alternating phenylenevinylene with dithenyl (thienothiadiazole) segments) having optical band gap 1.65 eV and 1.74 eV, respectively, were used as electron donor along with the PC₇₀BM as electron acceptor for the fabrication of bulk heterojunction solar cells. The power conversion efficiency (PCE) of BHJ devices based on P1:PC₇₀BM and P2:PC₇₀BM cast from THF solvent is about 2.84% and 2.34%, respectively, which is higher than the BHJ based on PCBM as electron acceptor. We have investigated the effect of mixed (1-chloronaphthalene (CN)/THF) solvent, modification of PEDOT:PSS layer and inserting of TiO₂ layer, on the photovoltaic performance of polymer solar cell. We have achieved power conversion efficiency of 5.07% for the polymer solar cells having structure ITO/PEDOT:PSS (modified)/P1:PC₇₀BM (CN/THF cast)/TiO₂/Al. The effect of solvent used for spin coating, modification of PEDOT:PSS layer and inclusion of TiO₂ layer has been discussed in detail.     

Novel transparent ternary nanocomposite films of trialkoxysilane-capped poly(methyl methacrylate)/zirconia/titania with incorporating networks

Novel ternary nanocomposite trialkoxysilane-capped poly(methyl methacrylate)/zirconia/titania optical films were successfully prepared through a nonaqueous in situ sol–gel method. The acrylic monomers used were methyl methacrylate (MMA) and 3-(trimethoxysilyl)propyl methacrylate (MSMA). PMMA/ZrO₂–TiO₂ incorporating networks formed from alcoholysis of poly(MMA-co-MSMA), zirconium n-butoxide and titanium isoproproxide. The structure, morphology and property of the obtained nanocomposite films were investigated by X-ray photoelectron spectra, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, scanning probe microscopy, thermogravimetric analyses, UV–vis spectrum and spectro-ellipsometer. The nanoparticle size, roughness, thermal stability, UV-shielding property, and refractive index of nanocomposite films increase with the increasing of inorganic contents. The formation mechanism and reason of such improvements were examined and interpreted in a theoretical model. The nanocomposite films possess interesting properties in thermal stability and optical response due to the uniform incorporating networks between organic polymer chains and inorganic clusters.     

Electro-optical properties of poly[di(2-thiophenyl)carborane] and its opto-electronic application

Electrochemical and optical properties of a hybrid carborane based polymer called poly(di(2-thiophenyl)carborane) (P1) obtained electrochemically were reported as well as its electrochromic device application. Thiophene donor units and m-carborane acceptor unit were combined under the same umbrella via donor–acceptor–donor approach to obtain di(2-thiophenyl)carborane (1). Contrary to the literature, extreme conditions like highly dried solvent or inert atmosphere were not used for polymerization and characterization. Polymer P1 has an ambipolar character since it exhibited a reversible oxidation peak at a half wave potential (E_1/2) of 1.08 V and a quasi reversible reduction peak at E_1/2 = −1.82 V vs. Ag/AgCl. The polymer film has an optical band gap of 1.95 eV with a maximum absorption band centered at 488 nm. Also, it exhibited multicolor electrochromic behavior between its reduced and oxidized states changing from dark orange to light blue. Furthermore, the electrochromic device prepared based on P1 film was stable and robust.