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Synthetic Metals (v.162, #3-4)

Editorial Board (pp. iii).

Synthesis and characteristics of novel benzothiazoyl-pyrazoline derivatives containing carbazole by Hai-Ying Wang; Jing-Jing Shi; Gang Chen; Xiao-Ping Xu; Shun-Jun Ji (pp. 241-246).
► Benzothiazoyl pyrazoline compounds containing carbazole have been synthesized. ► Compounds exhibited efficient emission from blue to green with high quantum yields. ► HOMO/LUMO energy levels were obtained by CV and theoretical calculation. ► All of the compounds possess of suited HOMO ranges (−5.78 to −5.55eV). ► Compounds might be used as hole-transporting materials for OLEDs.Novel optical materials of trichromophore carbazole-pyrazoline have been synthesized and fully characterized by means of1H,13C NMR, and HRMS. The optical, electrochemical properties were also investigated. As expected, these compounds exhibited efficient emission from blue to green with high quantum yields. The solvent effect on the fluorescence characteristics of the four compounds indicates that the emission wavelength was red-shifted with the increase of solvent polarity. Quantum chemical calculations were used to obtain optimized ground-state geometry by hybrid density functional theory (B3LYP) with 6-31G* basis set, spatial distributions of the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) levels of the compounds.

Keywords: Synthesis; Optical; Electrochemical; Pyrazoline; Benzothiazoyl; Carbazole


Synthesis, crystal structure and luminescent properties of transition metals complexes based on imidazole derivatives by Shumei Yue; Na Li; Jiangyu Bian; Tingting Hou; Jianfang Ma (pp. 247-256).
► SCN as ligand in the complexes. ► The crystal structures of complexes13 are good. ► Luminescent properties of these complexes are good.In this paper, we synthesized complexes of imidazole derivatives. The structures of complexesNi(L1)2(CNS)2 (complex1),Zn(L2)2(CNS)2 (complex2) andMnL3Cl2 (complex3) were determined by X-ray diffraction in those complexes. The space groups of complex1,2 and3 are C2c/c, P-1 and P21/n, respectively. Ni (II), Zn (II) ions are coordinated by four nitrogen atoms of ligands and two nitrogen atoms of thiocyanate. Mn(II) ion is coordinated by three nitrogen atoms of ligand and two chlorine atoms. Single crystal X-ray studies on complex2 and complex3 indicate that the molecules of the complexes2 and3 link together through intermolecular NH⋯S hydrogen bonds and NH⋯Cl hydrogen bonds, respectively. The DFT (Density Functional Theory) and luminescent properties of these complexes are discussed. The calculated results are in good agreement with the experimental data.

Keywords: Imidazole derivatives; Crystal structure; Uv–vis spectrum; Fluorescence spectrum; DFT


Study of the magnetic field effects on carriers’ mobility in polymer based light-emitting diodes by Jixiang Sun; Qiming Peng; Xianjie Li; Mingliang Li; Feng Li (pp. 257-260).
► Studying of the magnetic field effects on PLEDs. ► Research methods: the transient EL method and a phenomenological model. ► The rising edges overlap closely with and without the magnetic field. ► MFEs exist in the quasisteady state period and the turn-off period. ► No MFEs on the mobility of carries but the recombination process.The magnetic field effects on the carriers’ mobility have been investigated for poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonat) (PFO) based light emitting diodes by the transient electroluminescence (EL) method. The EL pulses can be divided into the following six regions: (a) a delay region; (b) a fast initial rising edge; (c) a second slower rising edge; (d) a quasisteady state; (e) a fast falling edge; and (f) a slow decay region. The effect of the external magnetic field on the different regions can be obtained by measuring the EL pulses both with and without a magnetic field. It is found that the external magnetic field has no effect on both the electron and hole mobility in PFO based light-emitting diodes when the driving voltage is above the onset of the electroluminescence.

Keywords: Electroluminescence (EL); Polymer light-emitting diodes (PLEDs); Mobility; Magnetic field effects (MFEs)


3D metal–organic frameworks polymers of Pr(III) and Eu(III) with pyridine-2,6-dicarboxylic acid: Synthesis, structure and luminescent properties by Li-rong Yang; Shuang Song; Huai-min Zhang; Wu Zhang; Lan-zhi Wu; Zhan-wei Bu; Tie-gang Ren (pp. 261-267).
► Two MOFs polymers {[Ln2(PDA)3(H2O)3]·H2O} n (Ln=Pr(1) and Eu(2)) were synthesized and characterized. ► Both the 3D frameworks are assembled from the structure units containing three types of rings via hydrogen bond and OCO bridges. ► The thermal decompositions of1 have been predicted with the help of thermal analyses and emission spectra of2 have been identified.Pyridine-2,6-dicarboxylic acid (H2PDA) was used for the synthesis of two MOFs polymers {[Ln2(PDA)3(H2O)3]·H2O} n (Ln=Pr(1) and Eu(2)) with Pr(NO3)3·6H2O and Eu(NO3)3·6H2O under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. Both compounds crystallize in monoclinic system, space group P 21/ c. Both of the two compounds are isomorphous and isostructural. Different rings exist in the title compounds and form the 2D metal–organic framework. The 3D structures are constructed through covalent bonds and hydrogen bonds. The thermal decompositions have been predicted with the help of thermal analyses (TG and DTG). Furthermore, the luminescent properties of2 were studied in the solution of DMF at room temperature.

Keywords: Metal–organic frameworks; Hydrothermal synthesis; Structure; Luminescent properties; Pyridine-2,6-dicarboxylic acid


Effect of self-assembly supramolecules on the electrical properties of polyaniline based hole transport layer by Tae Hwan Lim; Kyung Wha Oh; Seong Hun Kim (pp. 268-275).
Display Omitted► Polyaniline based film was used as a hole transport layer of organic solar cells. ► It is cost effective photovoltaic device compared with conventional one. ► Self assembly supramolecule was prepared to improve electrical property. ► Grafting polymerization with polystyrenesulfonic acid enables water dispersity. ► The efficiency of organic solar cells adapted our layer is measured at 3.4%.To increase the power conversion efficiency of organic solar cells (OSCs), polyaniline (PANI) based film was introduced to the hole transport layer (HTL) of OSCs in this study. Two steps were applied to obtain high conductivity and water solubility of PANI. First, self-assembly supramolecules (SAS) were blended with PANI to improve crystallinity. Second, poly(styrenesulfonic acid) (PSSA), hydrophilic polymer, was grafted on the PANI surface to improve dispersion in aqueous solutions and to increase the conductivity of PANI through a self-doping system. As a result, the conductivity of PANI based film (PANI/SAS16-gr-PSSA) could be improved and reached to 0.81S/cm in a nano layer state, since this innovative method prevents the polymer chains from the recoiling of PANI. The conductivity of PANI/SAS16-gr-PSSA is higher than that of poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) (0.01S/cm) and PANI-gr-PSSA (0.17S/cm). The energy level of the prepared PANI/SAS16-gr-PSSA nano layer is approximately 4.83eV, indicating that it is suitable for a hole transport layer between the ITO electrode and photoactive layer. The OSCs device made of PANI based HTL prepared in this study shows a high power conversion efficiency of approximately 3.4%, which is higher than that of OSCs with PEDOT:PSS (2.8%) and PANI-gr-PSSA (3.0%) layer.

Keywords: Organic solar cells; Polyaniline; Self assembly; Conductivity; Water solubility


Spectral analysis of near threshold random lasers by Randall C. Polson; Zeev V. Vardeny (pp. 276-280).
► Near threshold random lasing spectra are based on circles or spheres. ► The Fourier transform provides information to assign the emission peaks. ► The same analysis works for multiple random lasing systems.Emission spectra from random lasing systems typically have numerous narrow resonant lines. When excited very near to the laser threshold there are fewer resonant lines which clarify the emission spectrum analysis. We studied three different random lasing systems including π-conjugated polymer films, zinc oxide and TiO2 scatterers in dye solution. Fourier transform analysis of the laser emission spectra near threshold of each system shows that all the sharp lines are highly correlated, indicating that they originate from a single high symmetry resonant structure. The naturally formed microresonators have a circular geometry in the two-dimensional films, and transient spherical geometry in the scatterers/dye suspension.

Keywords: Random lasing; Fourier transform; Microresonator


Bi-functional electroluminescent and photovoltaic devices based on rubrene-doped poly(3-hexylthiophene):1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 blends by Yanhui Lou; Zhaokui Wang; Shigeki Naka; Hiroyuki Okada (pp. 281-284).
A schematic illustrating of the device and material structures upon investigation.Display Omitted► A light-emitting organic photovoltaic bi-functional device is successfully fabricated. ► The device performance is optimized by adjusting the rubrene doping ratio in P3HT:PCBM blend. ► 1.05% power convention efficiency and 65cd/m2 electroluminescence properties are obtained. ► Light-emitting organic photovoltaic is expected to provide useful information on the film defect in organic blends.Electroluminescence and photovoltaic properties were observed simultaneously in a small molecular rubrene-doped poly(3-hexylthiophene):1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 blends based organic solar cells (OSCs). With optimized rubrene doping ratio, the device showed photovoltaic (PV) property with a power convention efficiency 1.05% under illumination and electroluminescence (EL) characteristics with a maximum luminance 65cd/m2 at higher bias, respectively. It provides a new route to realize the PV and EL bi-functional organic devices. In addition, the EL imaging in OSCs is expected to provide valuable information in the film defect conditions for understanding the blends internal conditions, meliorating the film quality, and further improving the device performance.

Keywords: Organic solar cells; P3HT:PCBM blends; Rubrene doping; Bi-functional device


Vibrational investigations of new functionalized fullerenes by Bolesław Barszcz; Kornelia Lewandowska; Andrzej Graja; Sin-Tae Kim; Tae-Dong Kim; Kwang-Sup Lee (pp. 285-290).
► Two new functionalized fullerenes has been investigated. ► Vibrational spectra (Raman scattering and IR absorption) has been recorded. ► DFT calculations of the equilibrium geometry and normal modes frequencies have been performed. ► Influence of the bromine atom presence on the vibrational behaviour of the molecule has been discussed.The vibrational properties of two fullerene derivatives: C60-fused N-methylpyrrolidine-5-(12-bromododecyl)thiophenyl (C60TH-DcB) and its modification (C60TH-Dc) has been studied. The vibrational properties were determined using the Raman scattering and infrared absorption spectroscopies supported by the quantum chemical calculations. The difference between two investigated molecules is very subtle. In the C60TH-DcB there is a terminal bromine atom attached to the end of the alkyl chain, while in C60TH-Dc this one atom is absent. The differences in the experimental spectra of both molecules are rather small but clear and they correspond quite well with the calculation results. The quantum chemical calculations of the normal modes of vibration let us describe these fingerprints and assign them to the specific vibrations of various functional groups of the molecule.

Keywords: IR spectroscopy; Raman spectroscopy; DFT


Octupolar organoboron chromophores derived from terthienobenzene by Ying Chen; Guo-qun Liu; Yuan-yuan Wang; Ping Yu; Zhiqiang Liu; Qi Fang (pp. 291-295).
Two newTTB derived octupolar organo borane exhibited strong blue-green emission in common solvents under single or two-photon excitation ( Φfl>30%), as well as good thermal stability ( Tg>150°C).Display Omitted► Two new octupolar terthienobenzene (TTB) derivatives with dimesitylboryl as terminal acceptors were synthesized. ► These compounds show high fluorescence quantum yields and good thermal stabilities. ►TTB will allow enhanced π-electron delocalization, but may not be suitable for two-photon absorptions materials.Two novel octupolar organoboron compounds, namely 1,3,5-tris[5-(dimesitylboryl)thiophen-2-yl]terthienobenzene and 1,3,5-tris[4-(dimesitylboryl)phenyl]terthienobenzene, symmetrically extended from terthienobenzene (TTB) with dimesitylboryl groups as electron acceptors have been synthesized. TheseTTB derivatives exhibited strong blue-green emission in common solvents under single or two-photon excitation ( Φfl>30%), as well as good thermal stability ( Tg>150°C).

Keywords: Organoborane; Terthienobenzene; Two-photon excited fluorescence


Synthesis and photocatalytic activity of poly- o-phenylenediamine (PoPD)/TiO2 composite under VIS-light irradiation by Hui-Long Wang; De-Ying Zhao; Wen-Feng Jiang (pp. 296-302).
Display Omitted► The PoPD/TiO2 photocatalyst was prepared using UV light photoinitiating method. ► The photocatalyst had a high catalytic activity for methylene blue degradation. ► The photocatalyst exhibited easy separation and good reusable ability.Poly- o-phenylenediamine (PoPD)/TiO2 composite photocatalyst with high activity and easy separation was facilely synthesized using ultraviolet light photoinitiating method. In this method, hydroxyl radicals produced by TiO2 under the ultraviolet light irradiation replaced conventional oxidant such as ammonium persulfate (APS) to induce polymerization of o-phenylenediamine (oPD) monomer on the surface of TiO2. The factors that influence the synthesis of PoPD/TiO2 composite photocatalyst and the optimum reaction conditions were studied thoroughly. The as prepared PoPD/TiO2 composite photocatalyst was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and UV–vis absorption spectra. The results showed that a dense conductive PoPD layer with moderate thickness was formed on the surface of TiO2, which can favor adsorption of organic pollutants and make full use of visible light. The novel PoPD/TiO2 composite catalyst was evaluated for their photocatalytic activity towards the degradation of methylene blue (MB) under visible light irradiation. The results were compared with synthesized pure TiO2 nanoparticles and the enhanced degradation was obtained with PoPD/TiO2 composite photocatalyst. More significantly, the PoPD/TiO2 composite photocatalyst exhibited easy separation and less deactivation after several runs. The advantages of the prepared PoPD/TiO2 composite photocatalysts revealed its great practical potential in photocatalytic reactions.

Keywords: PoPD/TiO; 2; composite photocatalyst; Methylene blue (MB); Wastewater treatment; Visible light irradiation


Small molecular host based on carbazole and m-terphenyl derivatives for efficient solution processed organic light-emitting diodes by Xu Lin; Shiki Yagai; Akihide Kitamura; Dong Ryeol Hwang; Soo Young Park; Young-Seo Park; Jang-Joo Kim; Takashi Karatsu (pp. 303-308).
Display Omitted► Soluble phosphorescent hosts derived form carbazole and m-terphenyl were synthesized. ► Two hosts exhibit good solubility in common organic solvents. ► They have high glass transition temperatures ( Tg>160°C) and thermal stabilities. ► Phosphorescent organic light emitting diode Ir(ppy)3 was fabricated by spin coating. ► The device showed a luminance of 21,100cd/m2 and an efficiency of 15.0cd/A.Two soluble phosphorescent host materials, 1,4-bis(3,6-di([1,1′:3′,1″:3″,1‴:3‴,1⁗-quinquephenyl]-5″-yl)-9 H-carbazol-9-yl)benzene (P-mPCCP) and 1,4-bis(3,6-bis(4,4″-di-tert-butyl-[1,1′:3′,1″-terphenyl]-5′-yl)-9 H-carbazol-9-yl) benzene (T-mPCCP) derived form carbazole and m-terphenyl derivatives were designed and synthesized. These two hosts exhibit good solubility in common organic solvents and possess high glass transition temperature ( Tg>160°C) and thermal stability. P-mPCCP and T-mPCCP as the host materials doped with the guest of fac-Ir(ppy)3, we fabricated phosphorescent organic light emitting diodes (PHOLED) by spin coating process. The turn-on voltage of P-mPCCP and T-mPCCP composing device was 4.0 and 7.0eV and showed a maximum luminance of 21,100 and 3290cd/m2 and a maximum luminance efficiency of 15.0 and 7.6cd/A, respectively.

Keywords: Organic light emitting diode; Small molecular host materials; Carbazole; m; -Terphenyl


Fabrication and characterization of high solid content Co0.8Ni0.2Fe2O4/PVP composite nanofibers by direct-dispersed electrospinning by Ya Tang; Xinwei Wang; Qinghong Zhang; Yaogang Li; Hongzhi Wang (pp. 309-313).
► Composite nanofibers with high Co0.8Ni0.2Fe2O4 NPs contents were prepared by ES. ► Composite nanofibers have a narrow size distribution and evenly particles dispersion. ► Composite nanofibers demonstrated a superparamagnetic behavior.Composite nanofibers with a high Co0.8Ni0.2Fe2O4 nano-particulate content were fabricated by electrospinning. Silane coupling agent modified magnetic nanoparticles were directly dispersed in polyvinylpyrrolidone (PVP) solution at a mass ratio of 3:1. The surface morphologies and structures of the resulting nanofibers were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). FESEM and TEM results showed that the average diameter of the composite nanofibers was 350±30nm and the modified magnetic nanoparticles were evenly dispersed in polymer matrix. VSM results showed that the saturation magnetization of the composite nanofibers was up to 29.8emu/g and that the fibers also demonstrated superparamagnetic behavior.

Keywords: Modified nanoparticles; Magnetic materials; Polymers; Composite nanofibers


Heat capacity and phonon dispersion in polyselenophene in relation to the spectra of oligoselenophenes by Archana Gupta; Neetu Choudhary; Parag Agarwal; Poonam Tandon; V.D. Gupta (pp. 314-325).
Dispersion curves, heat capacity of polyselenophene and molecular electrostatic potential surfaces of octaselenophene and octatellurophene.Display Omitted► Phonon dispersion is obtained for polyselenophene in first Brillouin zone. ► Features of dispersion curves repulsion and exchange of character, van Hove singularities are discussed. ► Calculated heat capacity using Debye relation shows inflexion around 100K. ► The dispersion curves are found to observe the vibrational relationship of the spectra of the oligomers and the polymer. ► Molecular electrostatic potential surfaces of 8Se and 8Te differ significantly.Normal modes and their dispersion have been obtained for polyselenophene (PSe) in the reduced zone scheme using Wilson's GF matrix method as modified by Higg's for an infinite polymeric chain. The Urey Bradley potential field is obtained by least square fitting to the observed infrared and Raman bands. The results thus obtained agree well with the experimental IR and Raman values. The characteristic features of dispersion curves such as repulsion and exchange of character, crossing, van Hove type singularities have been discussed and possible explanation has been given. Heat capacity has been calculated via density-of-states using Debye relation in the temperature range 0–450K. Possible explanation for the inflexion region in the heat capacity variation is given. The spectra of the oligomers are checked with the finite–infinite spectral relationship and are found to be in agreement.

Keywords: Density-of-states; Phonon dispersion; Heat capacity; Vibrational dynamics; Polyselenophene


Constructions of polyaniline nanofiber-based electrochemical sensor for specific detection of nitrite and sensitive monitoring of ascorbic acid scavenging nitrite by Hui Wang; Pei-Hui Yang; Huai-Hong Cai; Jiye Cai (pp. 326-331).
Display Omitted► A novel polyaniline nanofiber (PANI-NF)-based electrochemical sensor was constructed. ► PANI-NF-based sensor sensitively detected nitrite with a detection limit of 0.05μM. ► PANI-NF-based sensor provided a strategy for monitoring of ascorbic acid scavenging nitrite.A novel polyaniline nanofiber (PANI-NF)-based electrochemical sensor was constructed for specific detection of nitrite and sensitive monitoring of ascorbic acid scavenging nitrite. The electrochemical behaviors of PANI-NF were studied by cyclic voltammetry and amperometry in the presence of nitrite. Results showed that nitrite reduction was enhanced by the nanostructure of PANI-NF film. Under low potential difference and acid medium, PANI-NF catalyzed the conversion of nitrite ion to nitric oxide, and then realized the reduction of nitrite ion. Under optimal experimental conditions, PANI-NF-based sensor demonstrated a fast response time of 5s and a detection limit of 0.05μM nitrite (signal-to-noise ratio, S/N=3), a linear range from 0.2μM to 35mM. This electrochemical sensor has been successfully applied to sensitively monitor ascorbic acid scavenging nitrite, and it has the potential of being used in nitrite detection.

Keywords: Polyaniline nanofiber; Electrochemical sensor; Nitrite detection; Ascorbic acid


Photoresponsive ambipolar transport characteristics of organic thin film transistors using soluble HB-ant-THT and PCBM composites by Seung Ho Yang; Mi Yeon Cho; Seong Gi Jo; Jin Sun Jung; Ki Hwa Jung; Suk Young Bae; Dong Hoon Choi; Sangsig Kim; Jinsoo Joo (pp. 332-336).
► Fabrication of organic thin film transistors (OTFTs) using composites of soluble p-type and n-type molecules. ► Observation of photoresponsive ambipolar transport property of OTFTs using Au–Au electrode. ► A weak photovoltaic effect of ambipolar OTFTs with Au–Al electrodes.We report on the photoresponsive ambipolar transport characteristics of organic thin film transistors (OTFTs) with two different types of electrodes using composites of soluble p-type x-shaped small molecules, 5,5′-(9,10-bis((4-hexylphenyl)ethynyl) anthracene-2,6-diyl)bis(ethyne-2,1-diyl)bis(2-hexylthiophene) (HB-ant-THT) and n-type molecules, (6,6)-phenyl-C61-butyric acid methyl ester (PCBM). Composites of HB-ant-THT and PCBM with varying concentration ratios were spin-coated as an active layer and thermal annealing was performed to increase the crystallinity of the active layer. The ambipolar transport characteristics were observed by applying the gate bias in OTFTs with a Au–Au electrode. With increasing the concentration of n-type PCBM, the hole mobility decreased while the electron mobility increased. We observed that the photocurrent in the OTFTs increased upon light irradiation. Ambipolar OTFTs prepared with Au–Al electrodes showed weak photovoltaic effect, and the power conversion efficiency of the devices increased with increasing the PCBM concentration.

Keywords: Ambipolar transistor; Organic thin film transistor; Photoresponse electrical characteristics; Photovoltaic effect; HB-ant-THT; PCBM


Synthesis of hollow poly(aniline- co-pyrrole)–Fe3O4 composite nanospheres and their microwave absorption behavior by Yao-Feng Zhu; Li Zhang; Toshiaki Natsuki; Ya-Qin Fu; Qing-Qing Ni (pp. 337-343).
► HPAP–Fe3O4 nanosphere is synthesized by in situ polymerization. ► HPAP–Fe3O4 nanosphere synthesized with hollow structure. ► HPAP–Fe3O4 nanosphere is microwave absorbing material. ► Increasing magnetite in nanospheres will increase absorbing properties.Hollow poly(aniline- co-pyrrole)–Fe3O4 (HPAP–Fe3O4) nanospheres with significant electromagnetic properties were successfully prepared via the oxidative polymerization of a mixture of aniline and pyrrole in the presence of a magnetic fluid, using a non-ionic surfactant as a template. The products were characterized by field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, thermogravimetric analysis and X-ray photoelectron spectroscopy. The electromagnetic (EM) and microwave absorbing properties of the nanocomposites were also investigated. The HPAP–Fe3O4 nanospheres exhibit superparamagnetic properties, and the conductivity increases with Fe3O4 content. The reflection loss evaluation based on the absorbing wall theory at 2mm thickness shows that the reflection loss is reinforced in the frequency range of 0.5–10GHz by the presence of Fe3O4 nanoparticles, and the frequency of minimum reflection loss shifts to a higher value with increasing Fe3O4 content. HPAP–Fe06 exhibits the best microwave absorbing property between 0.5 and 10GHz.

Keywords: Copolymer; Magnetite; Nanospheres; Hollow structures; Microwave absorbing property


Improving polyaniline processability by grafting acrylic copolymer by Elçin Coşkun; Shaida Marisol Martínez-Ramírez; Wilber Antunez-Flores; Claudia Alejandra Hernández-Escobar; Erasto Armando Zaragoza-Contreras (pp. 344-351).
Display Omitted► Grafting of acrylic copolymers on polyaniline–styrenesulfonate were synthesized via polymerization in dispersed medium. ► Styrenesulfonate was used as the doping agent and as the link between the polyaniline and the acrylic copolymers. ► Butyl acrylate presence in the copolymers improved adhesion and film properties. ► Electrical properties were dependent on the film properties.In this study styrenesulfonate of polyaniline/acrylic copolymers were synthesized via free radical polymerization through polymerization in dispersed medium. The resulting materials were applied onto glass-ITO slides using the air-brushing technique to obtain PAni based thin films. Analyses by scanning electron microscopy in TEM mode (STEM) indicated that depending on the acrylic monomer combination (methyl methacrylate, methacrylic acid or butyl acrylate) the adhesion on the substrate was better than styrenesulfonate of polyaniline (PAni–SSA) homopolymer. The effect of the combination of the acrylic monomers on the electrical properties was determined by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Results indicated that the electrical properties of the acrylic copolymer could be enhanced by varying the glass transition temperature. From these findings it was concluded that the inclusion of butyl acrylate in the copolymer was the critical condition to improve adhesion and electrical properties.

Keywords: Conducting polymer; Copolymer; Polyaniline; Styrenesulfonate


Blue organic light-emitting diodes based on pyrazoline phenyl derivative by P. Stakhira; S. Khomyak; V. Cherpak; D. Volyniuk; J. Simokaitiene; A. Tomkeviciene; N.A. Kukhta; J.V. Grazulevicius; A.V. Kukhta; X.W. Sun; H.V. Demir; Z. Hotra; L. Voznyak (pp. 352-355).
► The blue OLED based on pyrazoline phenyl derivative was fabricated. ► We conclude that TCz1 layer can be used as the electron transporting layer. ► We find that HPhP molecule is non-planar and possible to form stable amorphous films.The results of an experimental study of the electroluminescent device made of ITO/CuI/2,6-di-tert.-butyl-4-(2,5-diphenyl-3,4-dihydro-2H-pyrazol-3-yl)-phenol (HPhP)/3,6-Di(9-carbazolyl)-9-(2-ethylhexyl) carbazole (TCz1)/Ca:Al with efficacy up to 10.63cd/A are presented. HPhP provides blue emission with a peak wavelength at 445nm. The layer of TCz1 acts as an electron-transporting layer. In the framework of density functional theory (DFT) approach the geometry configuration and energy levels of HPhP are found being in a good agreement with spectral and cyclic voltammogram data.

Keywords: Organic light emitting diode; Blue emitting; Vacuum deposition; Pyrazoline derivative; Carbazole derivates


A systematic study of the electrochemical synthesis and spectroelectrochemical characterization of poly( o-chloroaniline) and poly( o-chloroaniline-co- o-toluidine) by Anwar-ul-Haq Ali Shah; Salma Bilal; Rudolf Holze (pp. 356-363).
► Electroactive polymers and copolymers of o-chloroaniline (OC) and o-toluidine (OT) were prepared by electrode potential cycling. ► Cyclic voltammetry and in situ UV–vis measurements suggest formation of poly( o-toluidine) (POT) based copolymers. ► In situ conductivities of the copolymers were lower by 1–3 orders of magnitude than those of POT. ► A claimed greatly increased conductivity of chemically synthesized copolymers of OT and OC could not be reproduced.Electroactive polymers and copolymers of o-chloroaniline (OC) and o-toluidine (OT) were prepared in aqueous acidic solution by electrode potential cycling. The resulting polymers and copolymers were subsequently characterized with cyclic voltammetry, in situ UV–vis spectroelectrochemical and in situ resistance measurements. Homopolymerization and copolymerization were carried out on a gold electrode with different feed concentrations of OC and OT. Poly( o-chloroaniline) (POC) showed conventional polyaniline-like cyclic voltammetry characteristics. However, the growth of POC was found to be dependent on OC concentration. An enhanced and maximum film growth of POC was observed at a concentration of 0.03M of OC. Above this concentration the polymer growth shows saturation. In case of copolymerization the polymer growth was decreased with increasing OC concentration in the feed. Cyclic voltammetry and in situ UV–vis measurements suggest formation of poly( o-toluidine) (POT) based copolymers. In situ conductivities of the copolymers were lower by 1–3 orders of magnitude than those of POT, which strongly denies the claim made in the literature about an increase of five orders of magnitude in conductivities of chemically synthesized copolymers of OT and OC.

Keywords: Poly(; o; -toluidine); Poly(; o; -chloroaniline); Copolymers; Cyclic voltammetry; In situ; conductivity; In situ; UV–Vis spectroelectrochemistry


Synthesis and electrochemical properties of a silyl-substituted tetrathiafulvalene derivative by Hongqi Li; Yaping Wang; Zhongbao Zhang; Lin Li; Jiajian Peng (pp. 364-367).
A new tetrathiafulvalene (TTF) derivative and the related silyl-substituted 1,3-dithiole-2-(thi)one were synthesized and characterized by1H NMR,13C NMR,29Si NMR, MS and IR spectra. Single crystal structure of the 1,3-dithiole-2-thione compound revealed the high degree of conjugation of the five-membered ring moiety in the DMIT compound. The electrochemical property of the new TTF derivative was studied by cyclic voltammetry. Formation of charge-transfer complex between the new donor and DDQ was demonstrated.Display Omitted► A silyl-substituted TTF and 1,3-dithiole-2-(thi)one were synthesized. ► Their structures were confirmed by NMR, MS and IR. ► Cyclic voltammetry of the new TTF derivative was determined. ► The formation of CT complex between the donor and DDQ was demonstrated.A new tetrathiafulvalene (TTF) derivative 2,3;6,7-bis[(2,2-dimethyl-2-silapropylene)dithio]-1,4,5,8-tetrathiafulvalene and the related silyl-substituted 1,3-dithiole-2-(thi)one were synthesized. Their structures were characterized by1H NMR,13C NMR,29Si NMR, MS and IR spectra. Single crystal structure of the 1,3-dithiole-2-thione compound revealed the high degree of conjugation of the five-membered ring moiety in the DMIT compound. The electrochemical properties of the new TTF derivative were studied by cyclic voltammetry. The formation of charge-transfer complex between the new donor and acceptor DDQ was demonstrated.

Keywords: Tetrathiafulvalene; Silyl; Electrochemistry; Crystal structure; Charge-transfer complex


Fabrication of solid aluminum electrolytic capacitors utilizing conductive polyaniline solutions by Ye Song; Longfei Jiang; Weixing Qi; Chao Lu; Xufei Zhu (pp. 368-374).
► We synthesize polyaniline solutions by direct and inverse emulsion polymerizations. ► We develop a solid aluminum electrolytic capacitor using polyaniline solutions. ► We offer a simple and cost-effective fabrication method of polyaniline capacitors. ► The performance of the capacitors can be further improved by secondary doping. ► The capacitors have very low impedances and excellent high-temperature durability.To overcome the risk of electrolyte leakage and the shortcoming of higher impedance at high frequencies for the conventional aluminum electrolytic capacitors impregnated with electrolyte solutions, solid aluminum electrolytic capacitors employing conducting polyaniline (PANI) as a counter electrode were developed. The dodecylbenzenesulfonic acid (DBSA) doped PANI/chloroform solution, camphorsulfonic acid (CSA)–DBSA co-doped PANI/chloroform solution and DBSA doped PANI/toluene solution were synthesized by direct and inverse emulsion polymerization pathway. The capacitors using the solution of CSA–DBSA co-doped PANI/chloroform showed the best electrical properties. The performances of the PANI capacitors can be remarkably improved after secondary doping with m-cresol. The as-fabricated solid capacitors have very low impedances at high frequencies and excellent temperature characteristics as well as long shelf-life. The results can be ascribed to high conductivity and superior thermal stability for the CSA–DBSA co-doped PANI. Our strategy of using conductive PANI solution to fabricate the solid capacitors is not only compatible with the existing fabrication procedure for the conventional capacitor but also suitable for commercial mass production of low cost PANI.

Keywords: Aluminum electrolytic capacitor; Solid capacitor; Conductive polyaniline solution; Low impedance; Long life


Preparation and characterization of multiwalled carbon nanotube/poly(3-hexylthiophene) thermoelectric composite materials by Y. Du; S.Z. Shen; W.D. Yang; K.F. Cai; P.S. Casey (pp. 375-380).
► MWCNT/P3HT thermoelectric composites were prepared. ► The TE properties of the prepared composites were measured. ► A maximum power factor of ∼1.56×10−3μWm−1K−2 was obtained.Multiwalled carbon nanotube/poly(3-hexylthiophene) (MWCNT/P3HT) composites were prepared by oxidative polymerization of 3-hexylthiophene in a MWCNTs dispersed chloroform solution. The phase composition of the composite materials was analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The thermoelectric properties of the composite powders, after cold pressing into pellets, were measured at temperatures between 293 and 423K. The electrical conductivity of samples containing 30wt% MWCNT displayed a gradual decrease in conductivity from 0.13 to 0.11S/cm across this temperature range and was accompanied by an increased in the Seebeck coefficient from 9.7 to 11.3μV/K.

Keywords: Poly(3-hexylthiophene); Multiwalled carbon nanotube; Thermoelectric properties; Composite


Switchable surfaces of electroactive polymer brushes grafted from polythiophene ATRP-macroinitiator by Lisa Strover; Clément Roux; Jenny Malmström; Yiwen Pei; David E. Williams; Jadranka Travas-Sejdic (pp. 381-390).
Display Omitted► A novel conducting polymer ATRP macroinitiator is described and used to graft PS- b-PAA branches.► Electroactive polymer brushes described can be reversibly oxidized and reduced. ► A dramatic change in morphology is observed between the oxidized and reduced polymer brushes.Brush copolymers based on polyterthiophene have been synthesized with the aim of using them as electrically responsive layers in smart surfaces. A novel terthiophene monomer, which is polymerizable both chemically and electrochemically, was used to polymerize polyterthiophene backbones as precursors for grafting of sidechains. The precursor polymer is equipped with a bromoester, making it suitable for use as a macroinitiator for Atom Transfer Radical Polymerization (ATRP) of polystyrene- b-polyacrylate branches. In this paper we present the synthesis and characterization of this conductive poly(3′-(ethyl-2-bromopropionate)-2,2′:5′,2″-terthiophene)- g-(polystyrene- b-poly acrylic acid) (PBrTTh- g-(PS- b-PAA)) brush copolymer and demonstrate its reversible switching between conducting and insulating states, with accompanying changes in physical properties. We characterize morphological changes driven by the electrochemical switch with scanning electron microscopy and observe a microscale wetting–dewetting transition of brush copolymer films on the electrode.

Keywords: Conducting polymer; Polymer brush; Smart surface; ATRP


A new bulky trymethylsilylxylene substituted iridium(III) complex with picolinic acid as ancillary ligand: Synthesis; characterization and applications for efficient yellow-green emitting phosphorescent organic light emitting diodes by Moon Chan Hwang; K. Thangaraju; Ki Ho So; Sung-Chul Shin; Soon-Ki Kwon; Yun-Hi Kim (pp. 391-397).
► New Ir(dmtppy)2pic shows the PL emission at 520nm in solution. ► Ir(dmtppy)2pic has high thermal stability (Δ T5%: 356°C and Tg: 198°C). ► Ir(dmtppy)2pic in phosphorescent OLED emits the yellow-green emission. ► The higher device efficiencies of 10.2%, 30.2cd/A and 10.1lm/W were observed.We designed and synthesized a new bulky trimethylsilylxylene substituted iridium(III) complex with picolinic acid as ancillary ligand, bis(5-(2,5-dimethyl-4-(trimethylsilyl)phenyl)-2-phenylpyridine)-iridium(III) picolinate [Ir(dmtppy)2pic], by Suzuki coupling reaction and confirmed using various spectroscopic studies. The Thermogravimetric analysis shows the 5% weight loss (Δ T5%) at 356°C with the glass transition temperature ( Tg) of 198°C from differential scanning calorimetry studies. The photophysical and electrochemical studies show the photoluminescence emission at 520nm (in solution) with the band gap energy of 2.59eV. Ir(dmtppy)2pic dopant in phosphorescent organic light emitting diodes exhibits the yellow-green emission at 528nm with CIE color coordinates of (0.37, 0.58) with higher device current efficiency of 30.2cd/A, the external quantum efficiency of 10.2% and the power efficiency of 10.1lm/W.

Keywords: Phosphorescent organic light emitting diodes; Iridium(III) complex; Bulky trimethylsilyl xylene; Picolinic acid–ancillary ligand; Yellow-green emission; High efficiency


Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime by Qian Yang; Yuying Hao; Zhenguo Wang; Yunfei Li; Hua Wang; Bingshe Xu (pp. 398-401).
► LiF-doped TPBi as electron transport layer. ► Electrophosphorescent organic light-emitting diodes based on double-emitting layers. ► The efficiency and operational lifetime are remarkably improved. ► The device shows better stability at high current density.We demonstrate an excellent electrophosphorescent organic light-emitting diodes (PHOLEDs) with double-emitting layers (D-EML) and LiF-doped TPBi as electron transport layer (ETL), which has the structure of ITO/NPB (30nm)/CBP:Ir(ppy)3 (20nm)/TPBi:Ir(ppy)3 (10nm)/TPBi (10nm)/TPBi:LiF (40nm)/LiF (1.2nm)/Al (150nm). A peak current efficiency of 40.5cd/A and a maximum power efficiency of 23.7lm/W have been achieved, 1.99 and 2.95 times of those of the reference device [ITO/NPB (30nm)/CBP:Ir(ppy)3 (30nm)/TPBi (10nm)/Alq3 (40nm)/LiF (1.2nm)/Al (150nm)], respectively. And the device shows better stability than reference device at high current density. Moreover, the operational lifetime is improved, nearly 35 times of that of the reference device. We attribute mainly these improvement to the carriers’ self-balancing character of D-EML OLEDs, less numbers of heterojunction interface and better electron transport property of TPBi:LiF.

Keywords: Phosphorescent OLED; Double emission layers; Doped charge transport layers; High efficiency; Long lifetime


Low voltage top-emitting organic light emitting devices by using 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile by Sang Hee Cho; Sang Woo Pyo; Min Chul Suh (pp. 402-405).
Display Omitted► The method to decrease operating voltage of OLED devices by using HAT-CN molecules. ► Comparison of OLED devices with HAT-CN interlayer inside HTL and HAT-CN doped HTL. ► Effect of operating voltage by HAT-CN doping ratio. ► Thick top-emitting OLED devices with very low efficiency roll-off behavior.Two different types of hole transport layers are applied to the standard top-emitting green organic light emitting diodes (OLEDs) with relatively thick microcavity structure for a low voltage operation. An 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN), a well-known electron accepting material, was utilized as an interlayer which induces an interfacial charge transfer. The position of an interlayer was determined by investigation of device characteristics of four different types of hole only devices. The optimized device with very thin HAT-CN layer (∼5nm) sandwiched between N, N′-diphenyl- N, N′-bis-[4-(phenyl- m-tolylamino)-phenyl]-biphenyl-4,4′-diamine (DNTPD) layers showed very stable current efficiency and power efficiency behavior with low roll-off characteristic. The performances of the device with interlayer were compared to those of p-doped device (3%). Very interestingly, the device with HAT-CN interlayer showed very similar operating voltage behavior as well as current/power efficiency behavior compared to that prepared with p-doped hole transport layer (HTL).

Keywords: Low-voltage; Top-emitting, Interlayer; Charge transfer; Thick hole transport layer; Microcavity structure


Photocurrent stability and responsivity in the n-type Si/ZnO-doped conducting polymer photovoltaic device by Yow-Jon Lin; Ting-Hong Su; Jung-Chung Lin; Yu-Chao Su (pp. 406-409).
► The effect of ZnO doping on a performance of the PEDOT:PSS/Si device was researched. ► ZnO doping led to reductions in resistivity and charge-trap density in PEDOT:PSS. ► The improved photocurrent stability was observed by incorporating ZnO into PEDOT:PSS. ► The enhanced responsivity is interpreted by the device rectifying performance.In this study, the effect of the incorporation of ZnO nanoparticles into poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) on the photovoltaic property and photoresponse in the n-type Si/PEDOT:PSS device was examined. The enhanced responsivity by ZnO doping can be interpreted by the external light injection and the device rectifying performance. The improved photocurrent stability by incorporation of ZnO nanoparticles into PEDOT:PSS can be explained by the reduced charge-trap density in the ZnO-doped PEDOT:PSS film.

Keywords: Polymer; Photoresponse; ZnO; Si; Conductivity; Defect


Synthesis and supercapacitive properties of electrodeposited polyaniline composite electrode on acrylonitrile-butadiene rubber as a flexible current collector by Hyeon Woo Cho; Lovely Rose Hepowit; Ho-Seong Nam; Sang Hern Kim; Yong Min Lee; Jong Huy Kim; Kwang Man Kim; Jang Myoun Ko (pp. 410-413).
► Acrylonitrile-butadiene rubber (NBR) is newly used as a flexible current collector to prepare a conductive composite sheet with vapor-grown carbon fiber. ► The as-prepared VGCF/NBR composite sheet is electrodeposited by aniline monomer to yield a polyaniline (PANI)/VGCF/NBR composite electrode for supercapacitors. ► The PANI/VGCF/NBR electrode shows a maximum specific capacitance of 271Fg−1.Flexible sheets consisting of acrylonitrile-butadiene rubber (NBR) and vapor-grown carbon fiber (VGCF) are newly prepared varying the composition (VGCF 20–30wt.%) for use as a current collector of supercapacitor electrodes. The as-prepared VGCF/NBR is then electrodeposited by aniline using a potentiodynamic cyclic voltammetry to yield a polyaniline (PANI)/VGCF/NBR composite electrode. It is confirmed that the electrical conductivity of VGCF/NBR current collector can be enhanced as the content of VGCF increases. Cyclic voltammetry result for the PANI/VGCF/NBR composites shows that the sample with 30wt.% VGCF achieves a maximum specific capacitance (271.8Fg−1) at 5mVs−1 and also reaches a superior specific capacitance at high scan rates. Such supercapacitor performance is possibly originated from the synergistic effect consisting of higher polarity of nitrile groups in NBR, conducting pathway of VGCF, and electroactive property of PANI.

Keywords: Acrylonitrile-butadiene rubber; Vapor-grown carbon fiber; Polyaniline; Flexible current collector; Supercapacitor

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