Structural, dielectric and electrical properties of Pb(SnTi)O3 ferroelectric system

We have synthesized (PST) with x=0.45, 0.55, 0.65 ferroelectric ceramics by a solid-state reaction technique and performed preliminary X-ray diffraction (XRD) analysis and the temperature and frequency dependence dielectric measurements on them. The a.c. and d.c. conductivities have been investigated over a wide range of temperature and the activation energy have also been calculated. It is observed that: (i) the relative dielectric permittivity () and loss tangent (tan ) are dependent on frequency, (ii) the temperature of dielectric permittivity maximum shifts toward lower temperature side, (iii) permittivity maximum decreases with the increase of Sn content in the (PST) compounds and (iv) no frequency dispersion of the dielectric permittivity reveals the no-relaxor behavior of the materials.     

Synthesis, characterization and electrical properties of poly(dibromoaniline-co-aniline)s

The chemical copolymerization of aniline and 2,5-dibromoaniline or 2,6-dibromoaniline by oxidation with K₂Cr₂O₇ in H₂SO₄/acetonitrile media has been carried out. Copolymer composition can be effectively controlled varying the monomer feed ratio. When substituted aniline fraction is increased in the copolymer, the electrical conductivity () decreases; this effect is more important when 2,6-dibromoaniline is used. Thus, the conductivity can be controlled in a broad range, from 1.2 to 10^–6–10^–11 S·cm^–1 depending on the substituted aniline and the feed ratio. The relations between copolymer compositions and comonomer feed molar ratios shows that the aniline is slightly more reactive than dibromoanilines during the copolymerization process. All the copolymers were shown to be more processable than polyaniline.     

Structural, dielectric and electrical properties of Sm-modified Pb(SnTi)O3 ferroelectric system

We have synthesized (Pb_1-xSm_x)(Sn_yTi_1-y)_1-x/4O₃ (PSmST) polycrystalline ferroelectric ceramics with x = 005, 007, 01 and y = 0.45 by a solid-state reaction technique and performed preliminary X-ray diffraction (XRD) analysis, detailed temperature and frequency dependence dielectric measurements on them. The a.c. conductivity has been investigated over a wide range of temperature and the activation energy (E _a.c) has also been calculated. It is observed that (i) the dielectric permittivity (e) and loss tangent (tan °) are dependent on frequency, (ii) the temperature of dielectric permittivity maximum shifts toward lower temperature side with the increase of samarium ion (Sm₃) concentration at the Pb sites, and (iii) observed and calculated d-values of XRD patterns show that the compounds have been formed in orthorhombic single phase.     

Structural and optical properties of both pure poly(3-octylthiophene) (P3OT) and P3OT/fullerene films

We have investigated the structural and optical properties of P3OT and P3OT/fullerene thin films in view of their application as active layer in plastic solar cells. Films of these materials were prepared by spin coating from toluene solutions onto silicon substrates. Their optical properties were studied by spectroscopic ellipsometry, which provides the anisotropic dielectric function of the films. Moreover, structural properties were studied using X-ray diffraction. A close correlation between the results obtained by both methods could be found. Especially, the strong optical anisotropy of the films can be explained in terms of a preferable orientation of the polymer chains parallel to the substrate. The effect of the optical anisotropy on the performance of optoelectronic devices is discussed.     

Optical and electrical properties of soluble copolymers of pyrrole-thiophene-3-decylthiophene

Three novel soluble copolymers of pyrrole(P)-thiophene(T)-3-decylthiophene (D) at different molar ratio of comonomers 4 : 1 : 5, 1 : 4 : 5 and 1 : 1 : 2 have been synthesized. NMR, FTIR, UV, emission spectroscopy, GPC, DSC, TGA and conductivity measurements were used to characterize these copolymers. The dark electrical conductivity increases from 3–7 × 10^–6 S/m for undoped samples to 10^–1–10^–2 S/m for samples doped with 4% of iodine, and to 10–10² S/m for 16% of iodine in a form of I₃^–.     

导电聚(3,4-二氧乙基噻吩)应用研究进展

聚(3,4-二氧乙基噻吩)(PEDOT)是目前发现的导电态最稳定的导电高分子之一,在抗静电、塑料内存、电解电容器、有机太阳能电池、有机电致发光显示器件等领域得到了广泛研究和应用.本文简要综述PEDOT在这些领域的应用进展情况.     

Structural and electrical properties of Al doped ZnO thin films deposited at room temperature on poly(vinilidene fluoride) substrates

Transparent, conducting, Al-doped ZnO films have been deposited, by dc and pulsed dc magnetron sputtering, on glass and electroactive polymer (poly(vinylidene fluoride)–PVDF) substrates. Samples have been prepared at room temperature varying the argon sputtering pressure, after optimizing other processing conditions. All ZnO:Al films are polycrystalline and preferentially oriented along the [002] axis. Electrical resistivity around 3.3 × 10^− 3 Ω cm and optical transmittance of ~ 85% at 550 nm have been obtained for AZOY films deposited on glass, while a resistivity of 1.7 × 10^− 2 Ω cm and transmittance of ~ 70% at 550 nm have been attained in similar coatings on PVDF. One of the main parameters affecting film resistivity seems to be the roughness of the substrate.     

Structural and electrical properties of Gd3+ ion substituted CoGdxFe(2-x)O4 nano-ferrites

Nano particles of CoGdxFe(2-x)O4, with x = 0.0, 0.1, 0.3, 0.5 have been prepared by chemical co-precipitation method. The as synthesized particles are annealed at 300 degrees C for two hours to improve crystallinity. The X-ray diffraction patterns reveal the single cobalt ferrite phase formation and the average crystallite size decreases to 7 nm in the Gd3+ ion doped sample (with x = 0.5) compared to 27 nm in case of un-doped cobalt ferrite sample. The electrical properties for the different compositions of Gd3+ ion substituted cobalt ferrite material were studied in the frequency range 100 Hz to 10 MHz at room temperature using WK impedance analyzer. It is found that the electrical conductivity of the samples increases with increasing Gd3+ ion concentration. The results of our investigations reveal a strong dependence of material properties on Gd3+ ion doping.     

Synthesis and properties of diblock copolymers containing poly(3-hexylthiophene) and poly(fluorooctyl methacrylate)

This study reports the synthesis of regioregular poly(3-hexylthiophene)-b-poly(1H,1H-dihydro perfluorooctyl methacrylate) (P3HT-b-PFOMA) block copolymers by atom transfer radical polymerization of FOMA using P3HT macroinitiators. The P3HT macroinitiator was previously prepared by chemical modification of hydroxy terminated P3HT The block copolymers were characterized by 1H-NMR, 13C-NMR, GPC, DSC, TGA and TEM. The block copolymers are able to self-assemble into phase separated micellar thin film morphology from chloroform.     

Synthesis and characterization of conducting poly (1-aminonaphthalene), poly (2-aminonaphthalene) and poly (aniline-co-1-aminonaphthalene)

Poly (1&2)-aminonaphthalene and poly (aniline-co-1-aminonaphthalene) have been synthesized in high yields by chemical oxidative polymerization method. The polymers are soluble in polar solvents such as DMSO, NMP etc. In PNA-2 as head-to-tail coupling cannot occur, the electrical conductivity is lower than PNA-1. The copolymer exhibits distinct morphology, higher viscosity, characteristic exciton peak, appreciable thermal stability and electrical conductivity compared to PNA-1.     

Enhanced Electrical Properties in Carbon Nanotube/Poly （3-hexylthiophene） Nanocomposites Formed Through Non-Covalent Functionalization

Poly(3-hexylthiophene) (P3HT) has received much attention as a good candidate to replace inorganic semiconductors for flexible electronics due to its solution-processability. However, the low charge mobility of P3HT is an obstacle to its commercialization. To overcome this problem, we propose a new non-covalent functionalization method for carbon nanotubes (CNTs) for use in CNT/P3HT nanocomposites. By using modified pyrene molecules with hydrophobic long alkyl chains, the non-covalently functionalized CNTs can become well dispersed in hydrophobic solutions and organic semiconductor matrices. Fabrication of organic thin-film transistors (OTFTs) from the non-covalently functionalized CNT/organic semiconductor nanocomposites shows that our non-covalent functionalization method significantly reduces damage to CNTs during functionalization when compared with covalent functionalization by treatment with acids. The OTFTs show 15 times enhancement of field effect mobility (1.5 × 10⁻² cm²/(V·s)) compared to the mobility of OTFTs made from pure P3HT. This enhancement is achieved by addition of only 0.25 wt% of CNTs to P3HT.      

Characterization and magnetic properties of conducting poly(N-vinylcarbazole)-capped magnetite nanocomposite Langmuir-Schaefer films

Functionalized poly(N-vinylcarbazole) (PVK) has been synthesized by an oxidative polymerization with capped magnetite nanoparticles (CMPs, 10, 20, and 30%) for the preparation of conducting polymer composites that possess both electrical and magnetic properties. Spectroscopic studies reveal the successful functionalization of the nanoparticles into the PVK matrix. I-V characteristics of the composite films show an increase in the conductivity of the PVK film due to the presence of CMPs. The magnetization data exhibit an appreciable hysteresis loop at room temperature. The composite samples reveal an ordered semi-conducting behavior.     

Microdisk laser emission and electrical properties of composite films based on poly(3-hexylthiophene)s with different stereoregularity

The optical and electrical properties of composite thin films of poly(3-hexylthiophene)s (PAT6s), processing different stereo-regularity originating from side-chain regio orders have been studied. The laser emission properties of PAT6 composite thin films in microdisk structure have been observed by pulsed photopumping. From the electrical and optical measurements, the electrical conductivity and the quantum efficiency of the PAT6 composite films were estimated. The emission and conductivity depending on the mixture ratios were discussed by taking the stereo-regularity of the molecular structure into consideration.