Solid‐State Active Elements Based on Dyes and Prepared by a Sol‐Gel Method

A new method is suggested for producing the solgel matrices with the molecules of laser dyes introduced into them. The curves of tuning lasing in Rhodamine 6G, Rhodamine 4S, Rhodamine 101, and phenylamine 430 in these matrices are obtained. The total range of tuning is 550–650 nm at a pumping energy of 4 mJ. The halfwidth of the generation spectrum is independent of the pumping energy to 4 mJ and comprises 0.3 ± 0.1 nm. The main factors forming the generation spectrum are noted.     

Effect of Annealing on Microstructure and Electrical Characteristics of Doped Poly （3-Hexylthiophene） Films

The effect of annealing on the microstructure and electrical characteristics of poly （3-hexylthiophene） （P3HT） films doped with very small amounts of the electron acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane （F4-TCNQ） is studied. X-ray diffraction and UV-vis spectrum studies show that unlike the pure P3HT film, the thermal treatment on the doped fihns under an Ar atmosphere can effectively enhance the crystalline order of P3HT films, as well as successfully facilitate the orientation of the polymer chains. This improvement is attributed to the electrostatic force between P3HT and F4-TCNQ molecules. This force induces the polymer chains to crystallize and orient during the annealing process. As a result, annealing significantly improves performance, especially for the Ion/Ioff ratio of the TFTs based on the doped P3HT films.     

Electrochemical Synthesis and Structure of Poly(2‐methyl‐1‐naphthylamine) Films

A novel polymer, poly(2‐methyl‐1‐naphthylamine), which was synthesized electrochemically at various temperatures from a solution containing 2‐methyl‐1‐naphthylamine, acetic acid and sodium acetate, was characterized by IR spectroscopy. The structural conclusions were based on comparisons of polymer spectra with the IR‐spectrum of the monomer, 2‐methyl‐1‐naphthylamine. IR spectroscopy indicates that the electropolymerization proceeds via the –NH₂ groups and that the poly(2‐methyl‐1‐naphthylamine) structure consists of imine (–N?C) and amine (–NH–C) links between naphthalene rings as well as a free methyl groups in the chains. An analysis of the “substitution pattern” region in the polymer's spectra suggests that the polymer molecules were formed via mixed N–C(4), N–C(5) and N–C(7) linkages between repeated units. The ratio of between the 1645 and 1620 cm^? 1 peak areas decreases with increased temperature during synthesis, indicating that 25°C is the best temperature to obtain higher molecular weights.     

Optical Security System Based on the Biometrics Using Holographic Storage Technique with a Simple Data Format

We implement a first practical holographic security system using electrical biometrics that combines optical encryption and digital holographic memory technologies. Optical information for identification includes a picture of face, a name, and a fingerprint, which has been spatially multiplexed by random phase mask used for a decryption key. For decryption in our biometric security system, a bit-error-detection method that compares the digital bit of live fingerprint with of fingerprint information extracted from hologram is used.     

Effect of Non‐Ideal Mixed Solvents on Dimensions of Poly(N‐Vinylpyrrolidone) and Poly(Methyl Methacrylate) Coils

An addition of a small amount of non‐solvent tetrahydrofuran (THF) to good solvent water gave rise to a strong solvent power for poly(N‐vinylpyrrolidone) (PVP). It was found that PVP coils in mixtures of water and THF first swelled as the fraction of THF was increased, and then the coils contracted after a critical composition of the solvent mixture based on the measurement of dilute solution viscosities. It was reached that the power of the mixed solvents was not the simple average of the power of individual components. The influence of the non‐ideal mixing of water and THF on the power of these mixtures for PVP and the dimensions of PVP coils was taken into account. Especially the formation of pseudo‐clathrate hydrate structure with the composition φ _THF ≈ 0.44 was found to be an important factor to change the solvation and dimensions of PVP coils. Some other solvent mixtures for PVP and poly(methyl methacrylate) (PMMA) were also found to be non‐ideal mixtures. The viscosities of these solvent mixtures could show positive or negative deviation from the values obtained from the addition rule. It was shown again that the influence of the non‐ideality of these solvent mixtures on the dimensions of polymer coils was great. The action of mixed solvents changed the dimension of polymer coils, not only because of excluded volume effects but also because of the different molecular interactions present in these mixed solvents.     

Improved Carrier Transfer in Red Organic Light Emitting Diodes Doped with Rubrene

A red organic light emitting diode doped with rubrene is constructed with the configuration of ITO/NPB/Alq3:rub-rene:DCM/Alq3/LiF/Al.In the device,N,N‘-bid-(1-naphthl)-N,N‘-diphenyl-1,1‘-biphenyl-4,4‘-diamice (NPB) is used as the hole-transporting layer,tris(8-quinolinolato) aluminium (Alq3) as the electron-transporting layer and Alq3 doped with 5,6,11,12-tetraphenylnaphthacene (rubrene) and 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) as the emitting layer.When the doping concentration of rubrene is 6% and that of DCM is 4%,red purity of the device is improved effectively.The experimental phenomena are explained as the result of the improved carrier transfer from rubrene to DCM.     

Top-Emitting Organic Light-Emitting Devices Based on Silicon Substrate with High Luminance and Low Turn-on Voltage

We have fabricated a top-emitting organic light-emitting device on silicon substrate with high yellow luminance based on 5,6,11,12-tetraphenylnaphthacene sub-monolayer. It consists of a thin layer of highly conductive silver as the semitransparent cathode and surfaced-modified Ag as the anode. The device turns on at 3 V with the luminance of 8.4 cd/m^2. The maximum current efficiency is 1.3 cd/A at 6 V and the luminance reaches 14790 cd/m^2 at 14 V. The performance of the device is excellent in top-emitting organic light-emitting devices according to our knowledge.     

A Multi‐purpose Flow System Based on Multi‐commutation

A multi‐purpose flow system designed with solenoid valves and micropumps is proposed. The independent control of each active device was exploited to implement dilutions, calibration with a single solution, standard additions, titrations and strategies to increase sample residence time without changing the manifold hardware. Sample dispersion coefficients between 1 and 7800 were achieved by changing the sample volume and exploiting zone sampling, with coefficient of variation estimated as 6.5% for the highest dilution. Calibration curves obtained from a single standard showed slopes in agreement with those obtained by conventional batch dilutions with variations of lower than 2% between days. The possibility of implementing the standard addition method or the stopped‐flow approach at different points of the manifold was demonstrated for creatinine determination in urine by the Jaffe reaction. Analytical curves for different sample residence times can be obtained for detecting matrix effects or for the analysis of colored samples. Titrations by the continuous variation method or binary search, as well as other possible applications, are discussed.     

Hydrogen Bonding Interactions in Miscible Blends of Poly(hydroxyether ester)s with Poly(N‐vinyl pyrrolidone)

Studies on the miscibility and intermolecular specific interactions in the blends of two structurally similar poly(hydroxyether ester)s, poly(hydroxyether terephthalate ester) (PHETE), and poly(hydroxyether benzoate) (PHEB) with poly(4‐vinyl pyrrolidone) (PVPy) are reported. In the miscible blends there are intermolecular specific interactions between PHEEs and PVPy. It was found that intercomponent hydrogen‐bonding interactions in PHETE/PVPy blends are much stronger than those in PHEB/PVPy blends. It seems that the higher ratio of hydroxyl to carbonyl groups results in the stronger intermolecular hydrogen bonding interactions. The difference in intermolecular specific interactions between the two miscible systems is interpreted on the basis of the impact of macromolecular structures on intermolecular specific interactions. The structural characteristics of macromolecular chains, such as chain connectivity, accessibility (or screening effect), and rigidity of the macromolecular chains have a profound effect on the intermolecular interactions. These factors constitute steric hindrance and reduce the specific interactions among functional groups. These factors can become dominant in the blends of polymers.     

High Efficiency Red Organic Light-Emitting Diodes Based on Microcavity Structure

We demonstrate high efficiency red organic light-emitting diodes （OLEDs） based on a planar microcavity comprised of a dielectric mirror and a metal mirror. The microcavity devices emitted red light at a peak wavelength of 610nm with a full width at half maximum （FWHM） of 25nm in the forward direction, and an enhancement of about 1.3 factor in electroluminescent （EL） efficiency has been experimentally achieved with respect to the conventional noncavity devices. For microcavity devices with the structure of distributed Bragg reflectors （DBR ） /indium-tin-oxide（ITO） /V2O5 /N2N′-di（naphthalene-1-yl）-N2N′-diphenyl-benzidine（NPB ） / 4-（dicy-anomethylene）-2-t-butyl-6（1,1,7,7-tetrame-thyljulolidyl-9-enyl）-4H-pyran（DCJTB）：tris（8-hydroxyquinoline） aluminium （Alq3）/Alq3/LiF/Al, the maximum brightness arrived at 37000cd/m^2 at a current density of 460.0mA/cm^2, and the current efficiency and power efficiency reach 13.7cd/A at a current density of 0.23 mA/cm^2 and 13.31m/W at a current density of 0.04 mA/cm^2, respectively.     

An Electro—Optical Modulator Based on GeO2—Doped Silica Ridge Waveguides with Thermal Poling

A Mach-Zehnder electro-optic modulator is designed and fabricated based on upper-clad GeO2-doped silica ridge waveguides with thermal poling.The electro-optic coefficient obtained is about 0.05pm/V and is polarizationinsensitive.An extinction ratio of over 17dB is achieved.The transmission loss of the modulator for the TE mode is 2-3dB higher than that for the TM mode after the poling.     

IR Dichroism of Langmuir–Blodgett Films Based on Fatty Acids

We propose a method of measurement and quantitative estimation of dichroic ratios of submicron laminated Langmuir–Blodgett films by the IR spectra of multiple attenuated internal reflection. The method has been used in calculating the angles of orientation of molecular chains of stearic and palmitic acids in the process of their molecular deposition on an optical substrate. It has been found that in the process of structural self-organization of ensembles the degree of orientation of macromolecules is the higher, the greater the number of links entering into the aliphatic chain.     

Influence of Thermal Annealing and Deposition Conditions on the Structure and Optical Properties of GRS‐Active Substrates Based on Silver Films

Using the methods of atomicforce microscopy, xray diffractometry, and spectrophotometry, we have studied the morphological, structural, and optical characteristics of GRSactive substrates based on original and annealed silver films. We show that the backing temperature during deposition is the factor which exerts the most substantial effect on the morphological and optical properties of silver films and also on their stability with time. The coefficients of the correlation of the deposition rate with the characteristics of the optical density spectra of silver films are calculated. It is found that hightemperature (350°C) annealing of a silver film leads to the selforganization of its surface into a quasiperiodic structure with semiellipsoidal islets. The contribution of the processes of excitation of plasma resonances to the formation of the optical density spectra is discussed. It is shown that as a result of thermal modification the concentration of the crystalline phase of silver in a silver film increases 2–3 times and also the dispersion of the orientation of crystallites decreases.     

Red Light—Emitting—Diode Based on an Organic Salt

A novel organic salt trans-4-[P-(N-ethyl-N-(hydroxylethyl)-amino) styryl]-N-methylpyridinium tetraphenylborate (abbreviated as ASPT) has been employed as an active layer in an organic electroluminescent device. Bright red emission with high quantum efficiency has been obtained. The brightness of the ASPT device is one order magnitude higher than that of Alq3 devices at about 12V. The device shows high thermal stability because of the ionic interaction within the organic salt molecules. It is assumed that the high performance of such a device is related to the formation of dipole moments in the ASPT layer.     

Effect of Ag Nanoparticles on Optical Properties of R6G Doped PMMA Films

The composite PMMA films containing Ag nanoparticles and rhodamine 6G are prepared. We investigate the fluorescence properties and nonlinear optical properties of R6G/PMMA films influenced by Ag nanoparticles. The fluorescence enhancement factor is about 3.3. The corresponding nonlinear refractive index is measured to be -2.423 ×10^-8 esu using the Z-scan technique, which is much enhanced compared with the R6G/PMMA film. The results indicate that these enhancements are attributed to surface plasmon resonance of Ag nanoparticles.     

Influence of Thermal Treatment on the Thermal Behavior of Poly‐L‐lactide

The influences of thermal treatment on cold crystallization and the thermal behavior of poly‐L‐lactide (PLLA) were investigated by DSC and polarizing microscopy. Both the cooling and heating rates had effects on cold crystallization. Double peaks were observed for the samples on subsequently heating at 10°C min^?1 after cooling between 5 and 20°C min^?1. The degrees of crystallinity dramatically increased with decreasing cooling rate, and the size of PLLA spherulites increased with a decrease in the cooling rate. Double cold crystallization peaks were also observed during heating traces at higher rates for this material after fast cooling (20°C min^?1) from the melt. The competition between the crystallization from the nuclei formed during cooling, and that from spontaneous nucleation might be responsible for the appearance of double peaks.     

Improved Quantum Efficiency of Organic Light Emitting Diodes with Gradiently Doped Double Emitting Zone

We investigate electroluminescent characteristics of gradiently doped organic light-emitting diodes, which were gradiently doped in both the hole and the electron-transporting layer to form a double emitting zone. The device structure was ITO/(15nm) CuPc/(60nm) NPB:rubrene/(30nm) Alq3:rubrene/(20nm) Alq3/(0.5nm) LiF/Al. We observed that charge carriers were well trapped by the dopant molecules and the main emitting zone was localized at the NPB:rubrene side close to the interface of NPB:rubrene/Alq3:rubrene. The quantum efficiency (cd/A) was enhanced to 5.89cd/A at 6V. We attributed this improvement to the charge carriers trapping and the emitting of the double emitting zone.     

Thermal Behavior of an Fe(III)‐2,9,16,23‐Tetramidephthalocyanine‐Grafted Poly(N‐Vinylcarbazole)

Abstract

The introduction of 2,9,16,23‐tetramide‐Fe(III)phthalocyanine [Fe(III)taPc] units into phosphorylated poly(N‐vinylcarbazole) yields an amorphous grafted polymer containing free carbazolyl groups, phosphonic acid attached to carbazolyl groups, and grafted Fe(III)taPc units as evidenced by infrared spectroscopy. Several thermal transitions were detected by differential scanning calorimetry (DSC). The thermodegradation of the grafted sample, analyzed by simultaneous thermogravimetry‐differential thermal analysis (TG‐DTA), showed successive endo‐ and exothermal reactions resulting from the development of a cross‐linked structure. To determine kinetic parameters, both isothermal and dynamic experiments were performed at the different steps of the degradation process and theoretical methods were applied.     

Conductivity of Metal–Dielectric–Semiconductor Structures Based on Ferroelectric Films

Physics of the Solid State - In this paper, we present the results of experimental studies of the frequency and temperature dependences of the electrical conductivity of...