Fanshun Meng

Novel soluble and thermally-stable fullerene dyad containing perylene

A novel fullerene dyad C606060–P1 in which a perylene moiety is attached to C60 through a pyrrolidine ring has been prepared by 1,3-dipolar cycloaddition of the azomethine ylides generated in situ from the corresponding aldehyde and sarcosine. Electrochemical and photophyscial studies of the dyad in solution have revealed that there is no significant ground-state electronic interaction between the covalently bonded perylene moiety and the fullerene. The photophysical investigations have also shown that there exists an effective photoinduced energy transfer from the perylene moiety to C60. A photovoltaic device made with the dyad has confirmed that photoinduced electron transfer does take place within the dyad; however, the efficiency of the electron transfer is negligible relative to the energy transfer.

Novel linear and tri-branched copolymers based on triphenylamine for non-doping emitting materials

Abstract Novel linear and tri-branched copolymers with triphenylamine and cyano groups in the main chain were synthesized by a concise route and an environment-friendly procedure without metal catalyst. They show strong fluorescence in solid state and can be used as non-doping emitter to fabricate emitting diodes. The single-layer electroluminescence devices with PVK or PEDOT buffer layer have been made with these copolymers as non-doping red–orange emitter, electron-transporting as well as hole-transporting material. The single-layer devices show preliminary results with maximum efficiency of 0.052% and EL wavelengths around 614 nm.

Synthesis of novel cyanine–fullerene dyads for photovoltaic devices

Two novel cyanine–fullerene dyads have been synthesized by means of the Prato reaction from the corresponding cyanine-aldehyde, N-methylglycine and C60. As well as a thorough characterization using MS-TOF, 1H-NMR, 13C-NMR and elemental analysis, the optical and electrochemical properties of these two dyads were investigated. The fluorescence of the cyanine–fullerene dyads was quenched efficiently as compared to the pristine cyanine, which we have attributed to photo-induced electron transfer from the cyanine to C60. The redox potentials obtained by cyclic voltammetry provide evidence that this electron transfer is energetically favorable. Single and double layer photovoltaic devices were fabricated to evaluate the photovoltaic properties of the dyad. The energetic conversion efficiency of the double layer device exceeds 0.1% under 3.1 mW cm−2 white light irradiation. The results show that cyanine–fullerene dyads are promising materials for photovoltaic devices.

Novel cyanine dyes with multi-carboxyl groups and their sensitization on nanocrystalline TiO2 electrode

Three novel cyanine dyes containing multi-carboxyl groups and triphenylamine have been synthesized and were used to sensitize nanocrystalline TiO 2 electrode. The cyanine dyes were characterized with IR, 1 H NMR and UV-vis. The amount of the dyes adsorbed on the electrode affects the photoelectrochemical properties. The short-circuit photocurrent of the cyanine dye adsorbed efficiently reaches 13.8 mA.cm -2 and the overall energy conversion efficiency is 2.12%.

Synthesis and spectral properties of soluble trimethylsilyl substituted metal-phthalocyanines

Abstract By in situ trapping of lithiated phthalocyanines with chlorotrimethylsilane, several highly soluble trimethylsilyl non-peripherally substituted phthalocyanines were synthesized. The photodegradation of the resultant ZnPcs in different organic solvents was found to follow quasi-first order kinetics and the degradation products were determined with the aid of GC–MS. A mechanism for the photodegradation process has been proposed and is supported by results from MO calculations.

Cyanine-fullerene dyad for application in broad spectral response photovoltaic devices

A novel cyanine-fullerene dyad is used as active layer in a heterostructure photovoltaic cell based on PEDOT and buckminsterfullerene C60. The photocurrent spectrum of the device matches the absorption spectrum of the film and shows monochromatic quantum efficiencies of 5.5% and fill factors above 0.35 at white light irradiation intensities up to 310 mW/cm2. By blending a long wavelength absorbing cyanine with the dyad, the photocurrent spectrum extends to 800 nm with appreciable monochromatic quantum efficiency. Sensitization by cyanine dyes demonstrates the possibility to achieve photovoltaic response in the near infrared.

Highly efficient cyanine dyes used for nanocrystalline TiO2 electrode sensitization

With the development made by Graetzel et al on solar cell, the studies on dye-sensitized nanocrystalline TiO2 solar cell have been widely investigated. Here we synthesized four cyanine dyes containing carboxyl group. The absorption spectra and fluorescent spectra of the dyes in solution and in adsorbed state on the surface semiconductor were measured. These dyes have high absorption coefficient (~10 5M-1 cm-1), which is a major factor that affects the conversion efficiency of the solar cell. These cyanine dyes were used to sensitize nanocrystalline TiO2, and the photoelectrochemical properties of the electrodes sensitized by these cyanine dyes were measured. From the absorption spectra of the electrode it can be seen that these dyes have been efficiently adsorbed on nanocrystalline TiO2. The maximum IPCE values of dye CY-1, CY-2, CY-3 and CY-4 were 42%, 51.8%, 75.9% and 22.2% respectively. The results show that cyanine dye derivatives are promising sensitizers for nanocrystalline solar cell.