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The quartz tube solid particle air receiver is a new type of solar receiver in which fluidized particles absorb the solar radiation directly and heat the air effectively, improving the efficiency of solar thermal power generation and reducing costs. In this article, transient numerical simulation was conducted to simulate the heat transfer and flow processes in single quartz tube under concentrated solar radiation. The results showed that the distribution of solid particles temperature was uniform in the fluidized region, which could overcome the problem of overheating in the volumetric solar receiver. The temperature difference between solid particles and air was no more than 25K, indicating that heat transfer between particles and air was very effective. Further, as the direct solar radiation increased, the average air temperature in the outlet increased while the thermal efficiency decreased. The high tube wall temperature caused heat loss to the environment by radiative and convective heat transfer. With the air inlet velocity increasing, the averaging air temperature in the outlet decreased while the efficiency of the receiver increased. The simulation results provided important reference for improving the performance of the quartz tube solid particle air receiver.

In this article, an innovative solid particle receiver was developed which suitable to be used as fluidized bed solar receiver. The receiver is composed of five quartz tubes with the flowing silicon carbide particles as absorber. The thermal performance of the receiver was tested using 10kWth solar furnace system in Badaling solar thermal power experimental platform of China. Three days experimental results are listed in this paper. The maximum outlet air temperature is 624.1 °C. The minimum temperature difference between particles and outlet air is below 10 °C which shows good heat ransfer performance inside the receiver. The experimental results well verified the technical feasibility of such receiver design.

A new fluorescent compound based on calix [4] arene skeleton was synthesized. Its complexation ability with transition metal ions, such as Fe3+, Co2+, Ni2+, Cu2+, Zn2+ and Ag+, was investigated by UV-vis and fluorescent spectra.

Well-defined poly(N-isopropyl acrylamide) (PNIPAAm) brushes on commercial hydrophobic poly(vinylidene fluoride) (PVDF) microfiltration membrane surfaces were prepared, via direct atom transfer radical polymerization (ATRP) with the secondary fluorinated site of PVDF as initiator and water as solvent at 80°C. The effect of solvents on the ATRP was studied in detail. The water as reaction solvent was in favor of surface-initiated ATRP of N-isopropyl acrylamide (NIPAAm) from secondary fluoride of PVDF membranes. The chemical composition and structure of the modified PVDF membrane surfaces were determined by attenuated total reflectance (ATR) Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface and cross-section morphology of membranes were studied by scanning electron microscopy (SEM). The pore sizes of the pristine PVDF membrane and the PNIPAAm-grafted PVDF membranes were measured using micro-image analysis and process software. The introduction of the well-defined PNIPAAm on the PVDF membrane gave rise to hydrophilicity. Water contact angles of PVDF membranes reduced after the surface grafting of PNIPAAm. Water fluxes and protein solution permeation experiments revealed that the PNIPAAm-grafted PVDF membranes exhibited temperature-responsive permeability. The unique microstructure of PNIPAAm brushes facilitated hydrophilicity below the lower critical solution temperature.

Novel cylindrical polymer brushes consisting of poly(diphenylacetylene) main chain and poly(poly(ethylene glycol) methyl ether monomethacrylate) (PPEGMA) side chains were synthesized by the diphenylacetylene macromonomer or side chain initiated atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether monomethacrylate (PEGMA) from an bromo isobutyryl-bearing poly(diphenylacetylene) (poly(BrDPA)) method. The diphenylacetylene macromonomer, namely, DPA–PPEGMA, were prepared by the ATRP of PEGMA from bromo isobutyryl-bearing diphenylacetylene. DPA–PPEGMA was polymerized successfully with WCl6–Ph4Sn catalyst to give high molecular weight polymer brushes poly(DPA–PPEGMA). Meanwhile, polymer brushes (PDPA-g-PPEGMA) were obtained by ATRP of PEGMA from poly(BrDPA). The molecular weight of the side chains of PPEGMA could be controlled simply by modulating the ATRP time. The macromonomer and polymer brushes are soluble in nonpolar solvents such as toluene and chloroform. The polymers of poly(BrDPA) and poly(DPA–PPEGMA) absorb in the longer wavelength region, with two peaks at around 370 and 414 nm. The polymers are thermally stable and exhibit double crystallization and melting peaks during the cooling and heating scans.

Strong intermolecular interactions usually result in decreases in solubility and fluorescence efficiency of organic molecules. Therefore, amorphous materials are highly pursued when designing solution-processable, electroluminescent organic molecules. In this paper, a non-planar binaphthyl moiety is presented as a way of reducing intermolecular interactions and four binaphthyl-containing molecules (BNCMs): green-emitting BBB and TBT as well as red-emitting BTBTB and TBBBT, are designed and synthesized. The photophysical and electrochemical properties of the molecules are systematically investigated and it is found that TBT, TBBBT, and BTBTB solutions show high photoluminescence (PL) quantum efficiencies of 0.41, 0.54, and 0.48, respectively. Based on the good solubility and amorphous film-forming ability of the synthesized BNCMs, double-layer structured organic light-emitting diodes (OLEDs) with BNCMs as emitting layer and poly(N-vinylcarbazole) (PVK) or a blend of poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] and PVK as hole-transporting layer are fabricated by a simple solution spin-coating procedure. Amongst those, the BTBTB based OLED, for example, reaches a high maximum luminance of 8315 cd · m−2 and a maximum luminous efficiency of 1.95 cd · A−1 at a low turn-on voltage of 2.2 V. This is one of the best performances of a spin-coated OLED reported so far. In addition, by doping the green and red BNCMs into a blue-emitting host material poly(9,9-dioctylfluorene-2,7-diyl) high performance white light-emitting diodes with pure white light emission and a maximum luminance of 4000 cd · m−2 are realized.

A D-π-A-π-D compound 4,7-bis{5′-[4″,4″-N, N-diphenylamino-styryl]thiophen-2′-yl}benzo[1,2,5-thiadiazole] (TPA-BTD-TPA) with triphenylamine (TPA) as electron-donor and benzothiadiazole (BTD) as electron-acceptor and linked via vinyl unit was synthesized and characterized. A stable intramolecular charge-transfer state enabled the molecule to expand the optical absorption band and prevented the occurrence of electron back-donation. Excellent film-forming property made it easy prepare homogeneous film using a spin-coating technique. Suitable energy levels were beneficial for the improvement of photovoltaic device performance. Photovoltaic cell based on TPA-BTD-TPA/[6,6]-phenyl C61-butyric acid methyl ester as a active layer was fabricated, and the optical conversion efficiency was 0.26% under the illumination of AM 1.5 (85 mW/cm2).

A newly and interestingly small organic molecule, (R)-2,2′-dimethoxyl-3,3′-di(phenyl-4-yl-diphenyl-amine)-[1,1′]-binaphthyl, was introduced into solid-state electrolyte to assemble dye-sensitized photoelectrical cell. With optimized molecular structure and composite porous TiO 2 electrode, the solid-state device without any additives in electrolyte converted light to electric efficiency with a 0.07%. Under the assistance of some functional small-molecules in the electrolyte, solid-state devices showed an attractive conversion efficiency of 0.55%. In addition, the positive effects of functional additives on the photoelectrical performance, such as inhibiting interface charge recombination, improving hole-transporting properties and penetration of solid-state electrolyte, were discussed experimentally and theoretically in detail.

Spectroscopic properties of new hyperbranched conjugated polymers functionalized in periphery with N,N-dimethylaniline and tert-butyl-benzene as terminal groups are investigated by one- and two-photon excitations. The absorption, fluorescence excitation and emission spectra are examined in chloroform and N,N-dimethylformamide. The two-photon excitation measurements show that the new hyperbranched conjugated polymer possesses large two-photon excitation cross section which makes it a very attractive candidate for the potential application as nonlinear optical materials. As an example, the two-photon induced three-dimensional data storage is also demonstrated.

An unsymmetrical organic compound with carbazole (Cz) as donor and benzothiadiazole (BTD) as acceptor (D-π-A-π∗-D∗) was designed and synthesized via simple Heck reaction. The unique crystal structure of Cz–BTD–Cz∗ shows a ladder-like packing mode. A two molecule pair stacks parallelly with each other in each packing unit. In each cell, one Cz moiety is connected with BTD by vinylene bond in same plane. However, the other Cz group is connected to BTD by a one-end vinyl bond in almost perpendicular position to the coplanar part of the molecule. The shortest intermolecular plane distance is 3.48 ± 0.1 A. The photophysical properties of Cz–BTD–Cz∗ in solution and in bulky crystalline powder state were studied. In bulk crystalline powder state, it has a red-shifted emission band peaked at 609 nm relative to that in solution, and the FWHM was reduced to only 58 nm. Electrochemical properties were also investigated.

A material compound, 9,9-bis{4′-[2″-(carbazolyl)-vinyl]-phenyl}fluorene (F-CZV), was specially synthesized and used to fabricate the efficient white organic light-emitting devices (WOLEDs). The absorption peaks appear at 340 nm and 346 nm in dilute dichloromethane solution and film, respectively. The photoluminescence peaks appear at 350 nm and 400 nm in the solution and film, respectively. Photoluminescent quantum yield in solution is ca 0.82 by using quinine sulfate as the standard. In an optimized electroluminescent device structure of ITO/NPB (40 nm)/F-CZV (30 nm)/BPhen (40 nm)/Mg:Ag, the saturated white-light emission was observed at Commission International De L’Eclairage (CIE) coordinates of (0.30, 0.33) at 10 V. The El spectrum of the device is close to independent of the applied driving voltage. It’s maximum brightness and current efficiency is 700 cd/m 2 and 0.41 cd/A, respectively.

Three kinds of novel organic materials containing binaphthyl units, BNOBPV, BNONV and BNOAV, were synthesized by Wittig–Horner reactions. Their photophysical and electroluminescent (EL) properties were studied. BNOBPV and BNONV exhibited pure blue light as emitting materials in organic light-emitting diodes (OLED) with EL spectra peaked at 444 nm and CIE coordinates around (0.157, 0.095) and (0.171, 0.112), respectively. BNOAV showed a red-shifted emission peaked at 496 nm, which may be ascribed to the contribution of anthracene moieties.

An organic compound with two triphenylamine moieties linked with binaphthyl at the 3,3'-positions (2,2'-dimethoxyl-3,3'-di(phenyl-4-yl-diphenyl-amine)-[1,1']-binaphthyl, TPA-BN-TPA) can be synthesized by Suzuki coupling. Amorphous and homogeneous films are obtained by either vacuum deposition or spin-coating from solution in good solvents, while single crystals are grown in an appropriate polar solvent. X-ray crystallography showed that a TPA-BN-TPA crystal is a multichannel structure containing solvent molecules in the channels. The intramolecular charge-transfer state resulting from amino conjugation effects is observed by solvatochromic experiments. The high glass-transition temperature (130 °C) and decomposition temperature (439 °C) of this material, in combination with its reversible oxidation property, make it a promising candidate as a hole-transport material for light-emitting diodes. With TPA-BN-TPA as the hole-transporting layer in an indium tin oxide/ TPA-BN-TPA/aluminum tris(8-hydroxyquinoline)/Mg:Ag device, a brightness of about 10100 cd m -2 at 15.6 V with a maximum efficiency of 3.85 cd A -1 is achieved, which is superior to a device with N,N'-di(1-naphthyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine as the hole-transporting layer under the same conditions. Other devices with TPA-BN-TPA as the blue-light-emitting layer or host for a blue dye emitter are also studied.

In this paper, the optical and photo-induced electron transfer properties of a new conjugated molecule, 4,7-bis{5′-[4″,4″- N , N -diphenylamino-styryl]thiphen-2′-yl} -benzo[1,2,5-thiadiazole] (simplified as TPA-th-TPA), were investigated. Using TPA-th-TPA as a photoactive layer, organic solar cells with three different architectures were fabricated by spin-coating method. The photosensitive layers of these architectures comprise pure TPA-th-TPA layer, heterojunction of bi-layered TPA-th-TPA and C 60 , and bulk-heterojunction of TPA-th-TPA and [6, 6]-phenyl C 61 -butyric acid methyl ester (PCBM) blend. Furthermore, towards the bulk-heterojunction devices, the effect of the cathode materials (Mg, Ca, LiF/Al, Ba) on the performance of the devices was studied. The power conversion efficiency reached 0.26% for the device based on the blend of TPA-th-TPA and PCBM with Ba/Al as the cathode.

Poled polymers are currently of great interest in second-order nonlinear optical (NLO) applications such as electro-optic (EO) modulation, optical switching, etc. The EO active chromophores doped in polymer matrices generally have large dipole moment. The strong electrostatic interaction between molecular dipoles causes orientation relaxation after poling, decrease of poling efficiency, phase separation, and etc. at high doping concentration. A new type of NLO chromophore with low ground-state dipole moment has been designed and synthesized. It was doped in PMMA polymer matrix. The electrostatic interaction between chromophore molecules in this doped film is reduced greatly. This provides a way to increase the doping level in guest-host poled polymer system. At a very high loading level of 52% wt. (N = 6.41 × 1020/ cm 3), which is over 2 times of the theoretically predicated value for the spherical shape molecules, reasonable film quality and dipole orientation stability have been achieved.

A carbazole compound was synthesized by Knovenagel condensation and characterized by the measurements of 1 H NMR, IR and melting point. A multilayer organic light-emitting diode (OLED) using this compound as an active layer was fabricated by vacuum-deposition. This OLED showed a turn-on voltage of approximately 4.5 V and a maximum luminance of 910 cd/m 2 . Additionally, the maximum luminous efficiency was found as 0.95 cd/A, at this point the device luminance was measured as 146 cd/m 2 at an operating voltage of 7 V. The coordinate value of CIE 1931 was calculated as ( x , y ) = (0.3843, 0.5345) from the electroluminescence (EL) spectrum, which suggested that the device can emit a yellow-green light.

Two series of hyperbranched conjugated polymers were synthesized via an A 3 + B 2 type Wittig reaction. The molecular weights of the polymers were successfully tuned by simply changing the feed ratio of the monomers. Polymers with higher molecular weights presented more efficient photoluminescence, higher thermal stability and higher performance of LEDs.

A novel luminescent conjugated polymer, poly[{9-(α-naphthyl)-3,6-divinylenecarbazolylene}-alt-co-(1,4-phenylene)] (PNVCP), bearing alternated 9-(α-naphthyl)-carbazole and benzene units, was synthesized via a Wittig–Horner reaction. The solubility, thermal, and optical properties were investigated. It was soluble in common organic solvents, such as tetrahydrofuran and 1,2-dichlororoethane. Thermogravimetric analysis and differential scanning calorimetry showed that the conjugated polymer exhibited good thermal stability up to 496°C with a glass-transition temperature higher than 110°C. The photoluminescence properties were studied. The polymer emits blue light and the quantum yield is 93% in solution. The emission spectra exhibited an obvious solvent effect. With the increase of the polarity of the solvents, the fluorescence spectra changed obviously and appeared to be redshifted at room temperature. The redshift was more obvious in aromatic solvents than in aliphatic solvents. When N,N-dimethylaniline was gradually added into the solution of the conjugated polymer, the emission intensity of the fluorescence decreased. In comparison, the emission intensity of the polymer showed invariability when 1,4-dicyanobenzene was added into the polymer solution. Moreover, the fluorescence of the polymer could be effectively quenched by fullerene. Overall, the synthesized polymer is a potential candidate material for fabrication of polymeric light-emitting devices. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 923–927, 2006

The formation of a cylinder-like helical conformation induced by solvation was observed from a conjugated polymer poly(N-octylcarbazole ethylene). The polymer was synthesized by McMurry condensation using N-octyl-3,6-diformylcarbazole as monomer, in which the alkylcarbazolyl group was functioned as a turn angle. IR analysis indicated that the double bond in the polymer chain mainly takes a cis- conformation. Computer simulation revealed that the polymer could form into a hollow tubular nano-structure with a cavity of less than 1 nm in diameter by folding its strand. The helical conformation formed by solvent induction was further proved by the measurements of circular dichroism (CD) spectrum, specific rotatory power and fluorescent (FL) spectra. Copyright © 2006 John Wiley & Sons, Ltd.

Two series of novel ternary copolyimides containing perylene and fluorene units in the backbone were synthesized by one-step polycondensation of diamine (4,4′-(9H-fluoren-9-ylidene)bisphenylamine, FBPA) with perylene dianhydride (3,4,9,10-perylenetetracarboxylic dianhydride, PTCDA) and a comonomer [4,4′-(hexafluoroisopropylidene) diphthalic anhydride, 6FDA or 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, BDTA]. The polymers were named as PFFx (PTCDA-FBPA-6FDA) and PFBx (PTCDA-FBPA-BTDA), respectively, and their chemical structures were identified by FT-IR spectra and elemental analyses. Perylene contents in the copolyimides were determined through a quantitative UV-vis spectroscopy method, which are in agreement with the values calculated from the added raw materials both for PFFx and PFBx. Gel permeation chromatography (GPC) measurement suggested that the weight average molecular weight (Mw) is in the range 2.1–5.09 × 104 and the molecular weight distribution (MWD) is 1.86–2.72 for PFFx, and those for PFBx are 2.64–4.73 × 104 and 2.44–2.92, respectively. Thermogravimetric analysis (TGA) measurements showed that the copolyimides are very thermally stable with a temperature of 10% weight loss (T10) in the range 546–563°C for PFFx, and 538–548°C for PFBx. The copolyimides also have good solubility in common organic solvents such as chloroform and tetrahydrofuran. These unique properties can be attributed to the existence of the bulky diphenylfluorene moieties in the polymer backbone. All the copolyimides can emit strong fluorescence both in solution and in films, which make them possibly be used as thermostable light-emitting materials for organic light-emitting diodes. Copyright © 2006 John Wiley & Sons, Ltd.

A novel rigid self-assembled monolayer derived from a perylene derivative, 3,4,9,10-perylene tetracarboxylic acid, was prepared on hydroxyl-bearing surfaces via an ester bond-linkage. Contact angle measurements, UV-visible spectra, cyclic voltammetry and atomic force microscopy characterization showed that densely packed, well-ordered monolayer was formed at the ITO and mica substrates. The as-grown PTA SAM was photoactive, as characterized by steady anodic photocurrent generation from the PTA monolayer modified ITO in a three-electrode photoelectrochemical cell upon illumination with the presence of electron sacrificer electrode in the electrolyte. The agreement of the photoaction spectrum with optical absorption spectrum demonstrates that the PTA dye-aggregate within the SAM is responsible for the photocurrent generation.

To obtain a dual-functional polymeric semiconductor for efficient red-light emission and high-performance photovoltaic cells, an alternating copolymer containing triphenylamine (TPA; as donors) and cyano-substituted phenylene (as acceptors), TPA-CNPPV, was synthesized by Wittig reaction. The polymer was characterized by FT-IR, 1H-NMR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Cyclic voltammetry (CV) measurements showed that the polymer presented reversible oxidation and reduction with relative low potentials, suggesting its good electron and hole-injection abilities. The photophysical properties of the light-emitting material were investigated in both solution and spin-coated film. Efficient red photoluminescence (PL; at 641 nm) was observed in the film. TPA-CNPPV possessed good film-forming property and thermal stability, lower band gap, efficient photoluminescence, good hole-injection ability and high electron affinity, which are highly desirable for realizing red-light emission in light-emitting diodes (LEDs) and achieving high-performance photovoltaic cells. This point was supported by the fabrication and characterization of optoelectronic devices. The single-layer light-emitting device of ITO/TPA-CNPPV/Al had relative high external quantum efficiency (0.06%), which was increased to 0.35% with PVK as hole-injection transport layer and Ba as cathode. ITO/PEDOT/TPA-CNPPV/Ba/Al showed dual function in both light-emitting devices and photodiodes. Photovoltaic cells with pristine TPA-CNPPV had energy conversion efficiency of 0.1% at 500 nm. The efficiency was improved to 1.1% under AM1.5 (78.2 mW/cm2) with a TPA-CNPPV/C60 weight ratio of 1:4.

A novel alternating conjugated copolymer (poly[(dioctyloxyphenylene vinylene)-alt-(2,1,3-benzothiadiazole)], C8-PPV-BT) consisting of electron-rich dioctyloxybenzene and electron-deficient 2,1,3-benzothiadiazole repeat units was synthesized via a Pd-catalyzed Heck cross:coupling polycondensation. The thermal, electrochemical, qptical properties, and phntophysics of C8-PPV-BT blended with [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) have been investigated, Photovoltaic devices of ITO/PEDOT-PSS/C8-PPV-BT + PCBM (1/4, w/w)/Bh/Al were fabricated and their photovoltaic parameters were measured. The results showed the energy conversion efficiency (η e ) and external quantum efficiency (EQE) were 0.335 and 11.7% (451 nm), respectively, under simulated solar light illumination having light intensity of 78.2 mW.(cm 2 )- (AM1.5), which were both higher than those of devices based on poly[(dioctyloxyphenylene ethynylene)-alt-(2,1,3-benzothiadiazole)] (C8-PPE-BT) and PCBM blend under the same conditions. Optical, electrochemical, and photovoltaic properties of C8-PPV-BT and C8-PPE-BT copolymers were also compared and discussed.

The photophysical processes of 9,9-bis[4'-[2''-phenyl-5''-(3'''-(methacryl-amido)phenyl)]-1'',3'',4''-oxadiazolylphenyl]fluorene (F-MAOP) formed by Heck reaction of 9,9-bis(4'-iodophenyl)fluorene (F-IP) and 2-phenyl-5-[3'-(methacrylamido)phenyl]-1,3,4-oxadiazole (OXD) have been carefully studied. The results show that the compound emits blue and blue-violet light and the emission spectra exhibit obvious solvent effect. With the increase of polarity of solvents, the fluorescence spectra change obviously and appear blue shift at room temperature. In addition, the light-emitting can be quenched by both electron donor (N,N-dimethylaniline, DMA) and electron acceptor (C60). When N,N-dimethylaniline is gradually added into the solution of F-MAOP, the emission intensities of fluorescence are unusually increased. But when the concentration of DMA beyond a certain scope, the emission intensities of fluorescence are gradually decreased. The dimolecular exciplex between F-MAOP and C60 are formed and the quenching effect follows the Stern-Volmer equation. Moreover, interaction between F-MAOP and carbon nanotubes (CNTs) is also studied by fluorescent quenching.

A novel alternating conjugated polymer (C12-PPE-BT) containing phenylene-ethynylene and benzothiadiazole (BT) units (unless otherwise specified, C12-PPE-BT is represented that the BT ratio is 50% (mol%)) was synthesized by cross-coupling polycondensation with bis (triphenylphosphine)-dichloropalladium (Pd(PPh 3 ) 2 Cl 2 ) and phase transfer catalyst(PTC). C12-PPE-BT was characterized by 1 H NMR, IR, TGA, DSC and elemental analysis. Its electrochemistry, photophysics and electroluminescence properties were discussed. The copolymer obtained possesses high thermal stability, high oxidation and reduction potentials, and high photoluminescence quantum yield. Devices based on C12-PPE-BT copolymer emit red light with λ max = 620 nm. The emission of phenylene-ethynylene segments almost completely disappeared manifested that the intrachain and/or interchain energy transfer from phenylene-ethynylene segments to BT units occurred.

A novel kind of redissolvable gold nanoparticles was prepared by using a poly(phenylene vinylene)-based hyperbranched conjugated polymer as stabilizing agent. The complexation between the surface gold atoms and the bipyridyl groups at the periphery of the hyperbranched polymer prevents the nanoparticles from aggregation. The surface plasmon band of the nanoparticles is insensitive to surrounding media due to the capping with organic layer. The fluorescence of the surface-attached conjugated macromolecule is significantly quenched by the gold nanocore. Solvent polarity effect suggests the occurrence of a photo-induced electron transfer process from the excited bound fluorophore to the nanocore.

A novel poly(p-phenylene vinylene) (PPV)/ poly(p-phenylene ethynylene) (PPE) block-copolymer was synthesized by a cross-coupling polycondensation with Pd(PPh 3 ) 2 Cl 2 and a phase-transfer catalyst, and was confirmed by 1 H NMR and IR spectroscopy and elemental analysis. The thermal, electrochemical, and photoluminescent properties of the new copolymer have been investigated. The incorporation of triple bonds into the cyano-substituted PPV (CN-PPV) backbone leads to higher oxidation and reduction potentials than poly(2-methoxy-5-(2-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV) and CN-PPV, potentially making the copolymer a good electron-transporting material for use in a light-emitting-diode device.

An alternating copolymer containing triphenylamine (TPA) and cyano-substituted benzene moieties, TPA-CNPPV was synthesized using the Wittig reaction. The monomers and polymer were characterized by H-NMR, FT-IR and mass spectroscopy (MS). The polymer shows good solubility in common organic solvents and excellent film-forming ability. Thermogravimetric analysis (TGA) demonstrates that the polymer has a degradation temperature (TD) of 600°C; differential scanning calorimetry (DSC) result indicates that the glass transition temperature (Tg) of TPA-CNPPV is 160°C, suggesting high thermal stability. The photophysical properties of the light-emitting material were investigated in both solution and spin-coated film. Photo-isomerization of the polymer was investigated by UV-vis and fluorescence spectra. The interaction between TPA-CNPPV and C60 was studied by fluorescence quenching. Copyright © 2004 John Wiley & Sons, Ltd.

The luminescent copolymer 2-phenyl-5-[3′-(methacrylamido)phenyl]-1,3,4-oxadiazole and vinylcarbazole (PMAPO–VCZ), combining hole-facilitating moiety, carbazole ring, and electron-facilitating moiety, 1,3,4-oxadiazole, as side groups, was synthesized by a radical polymerization of the olefinic monomer PMAPO and VCZ. For comparison, the homopolymer P-PMAPO was also synthesized by similar procedures. The solubility, thermal, and optical properties of the copolymers were investigated. The synthesized copolymer was soluble in common organic solvents but the homopolymer of PMAPO was dissolved only by hot THF. Thermogravimetric analysis and differential scanning calorimetry measurements showed that the copolymer and homopolymer exhibit good thermal stability up to 360 and 340°C with glass-transition temperatures higher than 105 and 65°C, respectively. The photoluminescence properties were investigated. The results showed that the copolymer emits blue and blue-green light and the emission spectra of monomer and polymers exhibit obvious solvent effect. With the increase of polarity of solvents, the fluorescence spectra distinctly change, appearing with a red shift at room temperature. The concentration-dependent emission spectra change significantly with the increase of concentration. In addition, when N,N-dimethylaniline (DMA) was gradually added to the solution of copolymers, the emission intensity of fluorescence was dramatically increased. However, when the concentration of DMA was increased beyond a certain level, the emission intensity of fluorescence gradually decreased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2777–2783, 2004

A novel copolymer has been synthesized by copolymerization of 2,2′-dimethacrylamido-1,1′-binaphthyl (DMBN) with vinylcarbazole (VCZ) and its fluorescence characterization has been studied. The results show that the copolymer (DMBN-VCZ) is soluble in some common organic solvents and the fluorescence of the copolymer (DMBN-VCZ) can be quenched by both electron donors and electron acceptors where the quenching effects follow the Stern–Volmer equation. The dimolecular exciplexes between copolymer (DMBN-VCZ) and strong electron donor or electron acceptor are formed. Moreover, the interaction between copolymer (DMBN-VCZ) and C60 is also studied by fluorescent quenching. Copyright © 2004 John Wiley & Sons, Ltd.

Three hyperbranched phenylene vinylenes (HPVs)—H-mn, H-es, and H-py—were used in fabricating polymer photovoltaic cells (PVCs). PVCs with photoactive layers composed of pure HPV, a blend of HPV and C60, and a blend of HPV, poly(2-methoxyl-5,2′-ethylhexyoxyl-1,4-phenylene vinylene) (MEH-PPV), and C60, were fabricated, and their current–voltage characteristics were measured and investigated. The PVC with photoactive layers composed of H-es and C60 showed promising photovoltaic characteristics, with an energy-conversion efficiency of 0.035%, when illuminated under 85 mW/cm2 white light. The short-circuit current and energy-conversion efficiency of the PVCs based on H-mn/C60 and H-py/C60 were greatly improved when they were blended with a small amount of MEH-PPV. The incident photon-to-collected-electron efficiency of the HPV/MEH-PPV/C60 PVCs indicated that both HPVs and MEH-PPV contributed to the photocurrent. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1459–1466, 2004

The photovoltaic applications of conjugated polymer/fullerene composites have attracted much attention from the scientific community. The photoinduced electron transfer and other related photophysical processes occurred in the composites are the central issues. Several kinds of conjugated polymers have been synthesized in our laboratory. Studies of their composites with fullerene are reviewed. We observed strong fluorescence quenching of these conjugated polymers on mixing them with C60 in dilute solution. Anion radical species of C60 were observed in ESR measurements as a result of photoinduced charge separation. The quenching constants vary with different conjugated polymers and thus provide a quantum measurement for the interaction between the donor and acceptor. Solar cells have been fabricated from these conjugated polymer/fullerene composites. Energy conversion efficiency up to 1.1% has been achieved.

Perylene-3,4,9,10-tetracarboxylic acid (PTCA) was found to form stable Langmuir films at the air/water interface through the coordination with Cu(II) ion in the subphase although the compound itself could not form monolayer on a plain water surface. The Langmuir films can be transferred onto solid substrates by a Langmuir–Schaefer (LS) method. Surface pressure–area isotherm and measurement of the UV–Vis and FT-IR spectra of the transferred LS films confirmed the coordination between the carboxylic group and Cu(II) ion in the Langmuir films. Atomic force microscopy (AFM) measurements indicated that the Langmuir film was composed of small nanoparticles with a diameter of several tens of nanometers. X-ray diffraction (XRD) measurement on the transferred LS films revealed that the film formed a clear layer structure with a distance of 3.9 nm, which was in agreement with the height measurement from the AFM.

We report photophysical and electroluminescence (EL) properties of three novel hyperbranched phenylene vinylenes (HPVs) with benzene as the core, 2,5-dimethyloxyl substituted phenylene vinylene as the connecting unit, and benzene, dimethylaniline or pyridine as the terminal group, respectively. The absorption maxima of the HPVs blue-shift from solution to the films due to their twisted molecular conformation. The emission spectra in the films red-shift compared to those in solution, which may originate from interchain excimer species. The thin films of the HPVs exhibit pretty high photoluminescence (PL) quantum yields around 50.5–87.8%. Blue–green light-emitting electrochemical cells (LECs) based on the HPVs have been demonstrated with turn-on voltages of 2.5–2.6 V. The ac impedance measurements indicate the operation of the LECs corresponds to an electrochemical doping model.

The strategy of introducing the chromophores with low ground state dipole moment had been discussed to overcome the effect of the electrostatic interaction between the chromophores in the poled polymer films on its nonlinearity. As a result, the effective nonlinear optical coefficient d33 of the poled films, containing the chromophores with μg in the range of 3.5–5.5 D, will enhance at least 15%, even over 30%, compared to that of 7.5 D if the first hyperpolarizabilities (β) of chromophores are in the same magnitudes. And, under the above assumption, the same level of the d33 could even be achieved by utilizing the chromophores with μg as low as 2.2 D.

A multiple charge-transfer second-order nonlinear optical (NLO) chromophore 2,3-bis(4-aminophenyl)-5,6-dicyanopyrazine (BAPDCP) was successfully designed and synthesized. It was characterized by 1H NMR, mass spectrometry, Fourier transform infrared spectroscopy, and elemental analysis. The first hyperpolarizability β of BAPDCP was measured with the Hyper–Rayleigh scattering technique, which was 123.5 × 10−30 esu. The donor-embedded prepolyimide and prepolyurea were also synthesized by a polyaddition reaction. Thermogravimetric analysis and differential scanning calorimetry demonstrated that either the chromophore or the polymers have fine thermal stability. The thin films of prepolymers were prepared by coating on ITO glass substrate and poled by corona poling at elevating temperature. The second-order NLO coefficients d33 of the films were measured by in situ second-harmonic generation measurements. The d33 were deduced as 27.7 and 16.5 pm/V for polyurea and polyimide at 1064 nm fundamental wavelength, respectively. The onset depoling temperature of the polyimide and polyurea were both as high as 200 °C. To understand the temperature effect to the orientation thermal stability of polyimide, two films were treated at different final poling temperatures. The depoling experimental results showed that the orientation stability is higher, as raising the final treated temperature but the d33 value are almost similar. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2846–2853, 2003

The novel low ground state dipole moment X-type second-order nonlinear optical (NLO) chromophores with dicyanovinyl group as acceptor and methylene-1,3-dithiole group as donor have been designed and theoretically investigated by employing AM1/FF approach. The electronic properties of the designed chromophores were investigated by ZINDO/S-CI method. The calculated results show that the ground state dipole moment ( μ g ) of the designed chromophores are as low as 2 D and the zero-frequency first hyperpolarizabilities ( β 0 ) of them can reach as high as 50×10 −30 esu. These characteristics are well coincided with the reported thermally stable X-type chromophores and the one-dimensional low μ g chromophores. It is considered that the low ground state dipole moments may originate from their structural properties (including the ring-locking effect, steric hindrance factor and donor and acceptor properties). The large β 0 values are analyzed by utilizing two-level model. In addition, the merit of the low μ g of the NLO chromophores when they are incorporated into polymers has been also discussed. With the decrease of μ g , the NLO coefficient d 33 of the poled polymers have not been reduced due to the increase of the number density of chromophores in polymers. So the suitable low μ g chromophores are one of the solutions for the optical loss and enhancing the NLO coefficient of the poled polymer in the practical applications.

A derivative of naphthalimide compounds (NAP) is synthesized in our laboratory, and a self-assembly film is fabricated through an ester bond between the −OH groups in NAP molecules and −COOH groups on modified mica. Then this film is used as a template, and CdS nanoparticles are deposited on it in situ. The morphology of CdS nanoparticles is disk-like, and the diameter is ca. 4 nm by atomic force microscopic (AFM) study. Further, electron transfer between organic films and CdS is deduced through the phenomenon of fluorescence quenching and theoretical analysis.

A series of light-emitting conjugated polymers alternatively involving carbazole and bivinylene arylene moieties in the main chain were synthesized via Wittig-Horner type copolymerization. The photoinduced charge transfer process relating to these polymers was investigated by using the technique of fluorescence spectroscopy. The interaction between excited copolymers and C60 in benzene solution was studied. The fluorescence quenching can be well described by the “sphere-of-action” mechanism. It is believed that two basic steps are involved in the quenching process, i.e. the diffusion of excitation within the conjugated polymers and the dissociation of the exctions trapped by fullerene. The radius of the sphere-of-action can be related to the excitation diffusion length, which depends on the lifetime of the exciton. The dynamic fluorescence quenching of the copolymers by another quencher, 1,4-dicyanobenzene (DCB) was also surveyed. Copolymers with different chain conformations show different temperature effects in the dynamic quenching. A planar conformation is beneficial for the quenching via bimolecular collision.

A series of conjugated hyperbranched molecules with 1,3,5-triphenylbenzene rings as cores and with different connecting groups have been synthesized. Their structures were characterized by FTIR, 1H-NMR and 13C-NMR. These molecules exhibit good solubility and film-forming ability. In particular, they have high thermal stability (TID > 350 °C). The spectroscopic properties of these molecules were studied both in solution and as spin-coated films. The twisted intramolecular charge transfer (TICT) state was observed in hyperbranched molecules containing triphenylamine as the connecting unit. Light emitting devices (ITO/PEDOT/hyperbranched molecule/Ba/Al) have been fabricated.

Two light-emitting conjugated polymers alternatively involving arylenevinylene and a N-alkyl carbazole moieties in the main chain were investigated. The formation of an intramolecular charge transfer state was probed within the repetition units of the copolymers. A tail absorption band and dual fluorescence were found for one of the copolymers, poly[(9-(2-ethyl-hexyl)-9H-carbazol-3,6-ylene)-alt-(anthracen-9,10-ylene) vinylene], Cz-PAV. Solvent polarity effects were studied by means of steady-state spectroscopy and fluorescence-lifetime measurements. Fluorescence emission spectra at 77 K were also explored. All the results show that a photoinduced intramolecular charge transfer state was formed in Cz-PAV. The formation of this state may be related to the electron affinity of the acceptor group contained in the copolymer and to the molecular conformation of the copolymer. Copyright © 2003 John Wiley & Sons, Ltd.

Covalently-bound self-assembled monolayer of a kind of functional hyperbranched polymer, pyridine-capped hyperbranched poly(para-phenylene vinylene) (Py-HPV), was prepared on hydrophilic quartz or single-crystal silicon substrates using siloxane self-assembly techniques. The assembling procedure was characterized by contact angle measurement, X-ray photoelectron spectroscopy (XPS), UV-vis spectra and fluorescence spectroscopy. Atomic force microscopy (AFM) was also used to investigate the surface morphology and microstructure of the resulting Py-HPV self-assembled monolayer. Copyright © 2003 John Wiley & Sons, Ltd.