-
[show abstract]
[hide abstract]
ABSTRACT: Perylene imides have been an object of research for 100 years and their derivatives are key n-type semiconductors in the field of organic electronics. While perylene diimides have been applied in many electronic and photonic devices, their use can be traced back to the first efficient organic solar cell. By functionalizing different positions of the in total 12 positions (four peri, four bay, and four ortho-positions) on the perylene core, perylene imides with significantly different optical, electronic and morphological properties may be prepared. Perylene imides and their derivatives have been used in several types of organic photovoltaics, including flat-, and bulk-heterojunction devices as well as dye-sensitized solar cells. Additionally perylene imides-based copolymers or oligomers play an important role in single junction devices. In this review, the relationship between the photovoltaic performance and the structure of perylene imides is discussed.
Advanced Materials 02/2012; 24(5):613-36. · 13.88 Impact Factor
-
Chemistry - An Asian Journal 03/2011; 6(7):1744-7. · 4.50 Impact Factor
-
Laser Physics Review 01/2011; 1(2):297 - 302.
-
[show abstract]
[hide abstract]
ABSTRACT: A modified poly (vinylidene fluoride) (PVDF) hollow fiber membrane with higher flux and flux recovery rate was prepared by γ-radiation induced grafting of acrylic acid (AA). The influence of radiation dose and monomer concentration on the grafting degree was investigated. The results indicated that the grafting degree increased in the lower monomer volume fraction until the monomer volume fraction exceeded 20%. The grafting degree increased with the increase of radiation dose. Structural and morphological of the original and grafted membrane surface were characterized by FT-IR, scanning electron microscopy (SEM). The results indicated that acrylic acid was grafted onto PVDF hollow fiber membrane and the grafted membrane was more hydrophilic than original PVDF. There was a slight increase of breaking strength and yield stress with the increase of the grafting degree of AA. The pure water flux increased initially but decreased subsequently with the raise of grafting degree. When the grafting degree was 4.4%, the maximum pure water flux reached 1496.3 L/m2 × h, 1.79 times of original membrane. The pure water flux, flux recovery rate and rejection ratio for bovine serum albumin could improve simultaneously in a low grafting degree (<4.4%).
Macromolecular Symposia 12/2010; 297(1):231 - 239.
-
[show abstract]
[hide abstract]
ABSTRACT: The role of alkyl chain substitution on the phase formation and core dynamics is studied in a series of diphenylamine functionalized perylenemonoimides (PMIs), by X-ray scattering, calorimetry and site-specific solid-state NMR techniques. In addition, the strong dipole associated with the donor-acceptor character of the molecules allow an investigation of the dynamics with dielectric spectroscopy. The self-assembly revealed an ordered phase only in PMIs with branched alkyl chains. This phase comprises a helical stacking of molecules with a molecular twist angle of 60 degrees. Results from solid-state NMR further pointed out the importance of intramolecular hydrogen bonding in stabilizing the intracolumnar packing within the ordered phase. Moreover, the core dynamics are frozen as revealed by the value of the dynamic order parameters and the reduced strength of dipolar relaxation. The kinetics of phase transformation from the isotropic to the ordered phase proceeds via a nucleation and growth mechanism, and the rates are dominated by the nucleation barrier. Within the isotropic phase the core dynamics display strong temperature dependence with rates that depend on the number of methylene units in the alkyl chains.
Journal of the American Chemical Society 06/2010; 132(21):7478-87. · 9.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: N,N'-bisoctylperylene diimides (PDIs) have been functionalized in the 1,7-position with terthiophenes of varying architecture giving three new donor-acceptor (D-A) compounds of the same molecular weight. Different conjugation lengths, arrangements, and connections of the thiophene units within themselves and toward the PDI core have strong effects on the optical, electronic, and photochemical properties of the D-A compounds. Like jigsaw pieces joined together to give different pictures, the terthiophenes are linked to PDIs to achieve different colors. These insights into tuning color and energy levels can open new possibilities for tailoring chromophores to their desired applications, e.g., organic photovoltaics or organic field effect transistors.
The Journal of Physical Chemistry B 04/2010; 114(45):14343-7. · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Mass transfer and electrochemical phenomena in the membrane electrode assembly (MEA) are the core components for modeling of solid-oxide fuel cell (SOFC). The general MEA model is simply governed with the Stefan-Maxwell equation for multicomponent gas diffusion, Ohm's law for the charge transfer and the current-overpotential equation for the polarization calculation. However, it has obvious discrepancy at high-fuel utilization or high-current density. An advanced MEA model is introduced based on the diffusion equivalent circuit model. The main purpose is to correct the real-gas concentrations at the triple-phase boundary by assuming that the resistance of surface diffusion is in series with that of the gaseous bulk diffusion. Thus, it can obtain good prediction of cell performance in a wide range by avoiding the decrement of effective gas diffusivity via unreasonable increment of the electrode tortuosity in the general MEA model. The mathematical model has been validated in the cases of H2H2O, COCO2 and H2CO fuel system. © 2009 American Institute of Chemical Engineers AIChE J, 2010
AIChE Journal 09/2009; 56(5):1363 - 1371. · 2.26 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Perylene dyes have been widely used as photoreceptors in organic photovoltaics because of their outstanding photo-, thermal and chemical stability as well as their excellent photophysical properties. Herein we describe a novel generation of perylene dyes based on N-(2,6-diisopropylphenyl)-perylene-3,4-dicarboximide. The optical properties of these novel perylenes can be finely tuned via the substituents in the 1-, 6- and 9-positions of the perylene core. The facile synthesis, tunable orbital and absorption properties, and electrochemical potentials help us to design efficient perylene sensitizers for solar-cell applications.
Chemistry 01/2009; 15(4):878-84. · 5.93 Impact Factor
-
Chen Li,
Jun-Ho Yum,
Soo-Jin Moon,
Andreas Herrmann,
Felix Eickemeyer,
Neil G Pschirer,
Peter Erk,
Jan Schöneboom,
Klaus Müllen,
Michael Grätzel,
Mohammad K Nazeeruddin
ChemSusChem 02/2008; 1(7):615-8. · 6.83 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Five novel perylene molecules with different intramolecular charge-transfer (ICT) characters have been synthesized. The relation between the ICT character for different donating groups and the results for their electro- and photochemical properties as well as their performance in nanostructured dye-sensitized solar cells (nDSC) are reported. With the stronger donors, we obtain a shift of the lowest unoccupied molecular orbital (LUMO) to more negative potential versus normal hydrogen electrode (NHE) as well as an increase the charge separation in the dye upon excitation. Ab initio calculations were used to analyze the effects on orbital energies and electron distribution with the different donors. Incorporating the dyes in nDSCs, we see a drastical improvement in the performance for the more polar dyes. In particular, we find a much improved photovoltage because of higher LUMO levels, allowing conduction band tuning in the TiO2 as well as a contribution from the permanent dipoles in the dyes. The photocurrent improves remarkably with increasing ICT character of the dyes. The external quantum efficiency reached over 70%, and the overall solar-to-electrical energy conversion efficiency was improved to almost 4% for the dye with highest ICT character, which can be compared with devices with the standard N719 dye (Ru(dcbpy)2(NCS)2) showing 6% under similar conditions. The performance is a significant improvement compared to previous reports for perylenes and lifts the performance from modest to promising. Initial stability tests show that the dye with the highest performance was spectrally stable after more than 2000 h of irradiation in a solar-cell device.
10/2007;
-
[show abstract]
[hide abstract]
ABSTRACT: Aim: To examine the possible protective effect of ginsenoside Rg1, an active component of ginseng, on lung injury caused by glutamate in vivo.Methods: The lungs of mice receiving glutamate (0.5 g/kg) and/or ginsenoside Rg1 (0.03 g/kg) via intraperitoneal administration were collected. The indexes of lung wet weight/ body weight ratios (LW/BW), lung wet/dry weight ratios (W/D), heart rate (HR), and breathing rate (BR) were determined. The activity of nitric oxide synthase (NOS), xanthine oxidase (XOD), superoxide dismutase (SOD), catalase (CAT), the content of NO, and malondialdehyde in the lung homogenate were measured. Results: Treatment with glutamate for 2 h increased LW/BW, W/D, HR, and BR. These changes were nearly abolished by pretreatment with ginsenoside Rg1 for 30 min before glutamate injection. An analysis of the lung homogenate demonstrated the protective effect as evidenced by the inhibition of NOS (12%) and XOD (50%) inactivity, the enhanced activity of SOD (20%) and CAT (25%). Conclusion: Ginsenoside Rg1 has a potential protective role in lung diseases associated with glutamate toxicity.
Acta Pharmacologica Sinica 02/2007; 28(3):392 - 397. · 1.95 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Dye-sensitized solar cells (DSCs), one kind of hybrid solar cells, are being intensively developed due to their high efficiency and low cost. One of the main factors to improve the efficiency is the minimization of the recombination of holes and electrons at the TiO2/dye/electrolyte interface. To suppress the charge recombination, dye arrangement on the TiO2 surface plays the pivotal role in DSCs. Herein we report three perylene sensitizers of various molecular sizes, which are derived fromthe introduction of different groups in the 1,6-positions of the perylene core. The same donor (di-p-tert-octylphenylamino) and acceptor (anhydride) moieties in these perylene sensitizers render them highly similar spectroscopic and electrochemical properties, which can be used to compare the effect of the dye-loading on the TiO2 surface, namely, the photovoltaic performance as a function of the sensitizer size. These results will help in better understanding the complex relationship between the molecular size and the device performance.
