Zonghao Huang

Photoelectric performance of poly(p-phenylene vinylene)/Fe3O4 nanofiber array

The authors report on the assembly and photoelectric performance of poly(p-phenylene vinylene) (PPV)/Fe3O4 nanofiber array. The composite nanofibers were fabricated by electrospinning of PPV precursor/Fe3O4 nanoparticle solution, followed by thermal conversion. The Fe3O4 nanoparticles were uniformly dispersed in the PPV matrix. During the electrospinning process, magnetic fields were used to orient the nanofibers. The resulting nanofiber array was assembled directly into a photoconductor device. The photoelectric performances of the devices have been investigated, which show notable light sensitivity, good response speed, wavelength sensitivity, and reproducibility. Electrospinning is thus proposed as a simple and versatile method of fabricating one-dimensional PPV-based photoconductor devices.

Study on EL emission region of polymer thin film in PPV LED

In this paper, the intensity ratios I( λ 1 = 515 nm ) /λ 2 = 550 nm ) of both electroluminescence ( EL ) and photoluminescence ( PL) spectra of poly( phenylene vinylene) (PPV) thin film in the same PPV light-emitting diode (LED) are measured in order to discuss the EL emission dominant region. In the EL spectrum, the ratio I(λ 1 )/I 1 (λ 2 ) decreased from 1,35 to 1.25, when the bias voltage increased from 4 to 12 V. In the PL spectrum, the ratios I 1 (λ 1 ) /I 1 (λ 2 ) and I 2 (λ 1 )/I 2 (λ 2 ) (here I I and I 2 denote the intensities emitting from the indium-tin oxide (ITO) glass side and the opposite side, respectively) approach 1.5 and 1.3, separately. Based on these results, it is deduced that the emission dominant region of EL of PPV thin film in a single-layer PPV LED is close to the top electrode and apart from that of PL.

Nonlinear optical properties for pyridines and stilbazoles adducted by borane

Nonlinear optical (NLO) properties of Me 2 N-4-C 5 H 4 N, MeO-4-C 6 H 4 -CH=CH-C 5 H 4 N, Me 2 N-4-C 6 H 4 -C≡C-C 5 H 4 N and their Lewis acidic borane adductions were studied by using quantum chemical AM1/Finite Field (FF) method. Calculational results indicated that NLO properties of this kind of compounds were improved substantially due to adduction by Lewis acidic borane.

Ag nanoparticles/PPV composite nanofibers with high and sensitive opto-electronic response

The novel Ag nanoparticles/poly(p-phenylene vinylene) [PPV] composite nanofibers were prepared by electrospinning. The transmission electron microscope image shows that the average diameter of composite fibers is about 500 nm and Ag nanoparticles are uniformly dispersed in the PPV matrix with an average diameter of about 25 nm. The Fourier transform infrared spectra suggest that there could be a coordination effect to a certain extent between the Ag atom and the π system of PPV, which is significantly favorable for the dissociation of photoexcitons and the charge transfer at the interface between the Ag nanoparticle and the PPV. The Au top electrode device of the single Ag/PPV composite nanofiber exhibits high and sensitive opto-electronic responses. Under light illumination of 5.76 mW/cm2 and voltage of 20 V, the photocurrent is over three times larger than the dark current under same voltage, which indicates that this kind of composite fiber is an excellent opto-electronic nanomaterial.

Preparation of Ligand Free Au NPs/PPV Composites with High Stability and Photo-electric Response

A novel kind of ligand free aurum nanoparticles (Au NPs)/poly(p-phenylene-vinylene) (PPV) composites was prepared via a simple approach. Although there were no ligands coating on the surface of the Au NPs, the Au NPs/PPV precursor composite exhibited excellent stability that no obvious variance was found as long as 6 months at ∼4 °C in aqueous and alcohol mixed solutions. This was attributed to the strong interaction between Au NPs and PPV precursor, which was further strengthened after heat transformation. Fourier transform infrared (FTIR) and Raman spectra showed the interaction between benzene ring in PPV and Au NPs led to the part transformation of the sp2 hybrid orbital into the sp3 one during the composite formation. As a result, the photoluminescence (PL) life time of PPV in the composite was longer than that of pure PPV. The Au NPs/PPV composite exhibited good photo-electric response, indicating their potential application in the area of the photoelectric conversion devices.

Preparation of Tunable Emissive Poly(ethylene oxide) Nanofibers by Doping with TPP and DCM

AbstractPoly(ethylene oxide) (PEO) nanofibers that were doubly-doped with a donor, 1,3,5-triphenyl-2-pyrzoline (TPP), and an acceptor, 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM), were prepared by electrospinning to be 200–300 nm in diameter. Fluorescence from DCM was caused by non-radiative Forster-type fluorescence resonance energy transfer from photo-excited TPP to DCM. The color of the fluorescence from the PEO-TPP/DCM nanofibers was controllable through variation of the TPP:DCM molar ratio and ranged from blue to orange to white.

Preparation and characterisation of photoelectric and electrochemical capability of polyimide doped with CdSe and CdSe/TiO2

Purpose – To evaluate the photoelectrochemical characteristics of polymer doped with CdSe and CdSe/TiO2 for improved photoelectric conversion efficiency.Design/methodology/approach – A method was set‐up to dope the nano‐CdSe with poly‐perylene‐tetracarboxylic imide (PPI) in the nano‐TiO2/ITO films, which were characterised by X‐ray diffraction; electrochemical analytical system; multifunctional grating spectrometer; digital photometer and ultrasonic cleanout instrument, etc.Findings – The modification of PPI doped with CdSe and CdSe/TiO2 showed significant elevation of the monochromatic incident photo‐to‐electron conversion efficiency (IPCE) of the photoelectrode, which was about 3 per cent. The doping caused a tone up separate efficiency of charge, restraining the complex of electron‐cavity by doped nano‐CdSe. Therefore, the photocurrent of the TiO2 film doped with nano‐CdSe was about three times higher than that without.Research limitations/implications – The mixed film could also be formed from conjuga...

Preparation and characterization of in situ electrospun ZnS nanoparticles/PPV nanofibers

Purpose – This paper aimed to prepare a kind of ZnS nanoparticles/poly(phenylene vinylene) (PPV) nanofibre and investigate its properties. Because the ZnS nanoparticles are important optoelectronic materials, their incorporation into one-dimensional (1D) nanoscale polymer matrices should be a meaningful subject for electrospinning. Design/methodology/approach – ZnS/PPV composite nanofibres with an average diameter of 600 nm were successfully prepared by a combination of the in situ method and electrospinning technique. The nanofibres were electrospun from Zn(CH3COO)2·2H2O and PPV precursor composite solution, and the ZnS/PPV fibres were obtained by exposure of the electrospun fibres to H2S gas to prepare ZnS nanoparticles in situ. Such fibres were characterised using X-ray Diffraction (XRD), Fourier transform infrared, transmission electron microscope (TEM), scanning electron microscope and photoluminescence (PL). The photoelectric properties of the fibres obtained were also investigated. Findings – XRD p...

Theory study of conduction mechanism of iodine-doped 1,4-cis-polyisoprene

Two-dimentional electronic energy bands of pristine and iodine doped 1,4-cis-polyisoprene (PI) are calculated by semiempirical EHMO-CO method. The results show that the conductivity of iodine doped PI results from the conduction of both parallel and perpendicular to the chain direction; the conductivity of interchain is higher than that of intrachain. I3n− (n<1) anions are the dominant contributors to the conductivity in parallel to the chain direction, while both I3n− anions and double bonds of interchains play an important role in conductivity in perpendicular to the chain direction.

Electronic properties of poly(1,4-phenylene methineimine) and its isomer

Summary form only given. We used the quantum chemistry EHMO-CO method to calculate the electronic structures of poly-(1,4-phenylene methieimine) and poly(iso-1, 4-phenylene methineimine). Comparing with the band structures of poly(1,4-phenylene vinylene), we can expect that poly(iso-1,4-phenylene methineimine) may possess better conductivity and polyazomethine may be a new kind of highly conducting polymer meterial.