-
[show abstract]
[hide abstract]
ABSTRACT: A series of fused thiophenes composed of fused alpha-oligothiophene units as building blocks, end-capped with either styrene or 1-pentyl-4-vinylbenzene groups, has been synthesized through Stille coupling reactions. The compounds have been fully characterized by means of (1)H NMR spectrometry, high-resolution mass spectrometry, and elemental analysis. The molecules present a trans-trans configuration between their double bonds, which has been verified and confirmed by Fourier-transform infrared spectroscopy and single-crystal X-ray diffraction analysis. The X-ray crystal structures showed pi-pi overlap and sulfur-sulfur interactions between the adjacent molecules. The decomposition temperatures were all found to be above 300 degrees C, indicating that compounds of this series possess excellent thermal stability. The fact that no phase transition occurs at low temperature indicates that they should be well-suited for application in devices. Moreover, they possess low HOMO energy levels, based on cyclic voltammetry measurements, and suitable energy gaps, as determined from their thin-film UV/Vis spectra. Thin-film X-ray diffraction analysis and atomic force microscopy revealed high crystallinity on supporting substrates. In addition, as the substrate temperature has a significant influence on the morphology and the degree of crystallinity, the device performance could be optimized by varying the substrate temperature. These materials were found to exhibit optimal field-effect performance, with a mobility of 0.17 cm(2) V(-1) s(-1) and an on/off ratio of 10(5), at a substrate temperature of 70 degrees C.
Chemistry 02/2010; 16(7):2231-9. · 5.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A novel preceramic polymer, polyzirconoxanesal (PZS), was synthesized efficiently by one-pot protocol. The PZS polymer was characterized by the techniques of Fourier transform infrared spectra (FTIR), nuclear magnetic resonance (1H-NMR and 13C-NMR) and gel permeation chromatography (GPC). The precursor exhibited excellent solubility and rheology for the processing of ceramic matrix fiber composites. Pyrolytic conversion of the preceramic polymer was studied by means of thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM) and element analysis. It is suggested that the polymer decomposed completely at 600°C and nanosized ZrC is formed at 1300°C for 2 hr in argon atmosphere with a yield of 68.5%. To the best of our knowledge, this is the lowest temperature reported in the literatures for preparing ZrC ceramics from preceramic polymers. The obtained ZrC particles exhibit spherical morphology with size ranged in 20–100 nm. Copyright © 2010 John Wiley & Sons, Ltd.
Polymers for Advanced Technologies 02/2010; 21(4):300 - 304. · 2.01 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Highly efficient light-emitting materials can be archived by a rational design that involves rigid dendron and π-conjugated chromophores. This strategy is exemplified by three unsymmetrical dendrimers 5-(2′,3′,4′,5′-tetraphenyl)phenyl-5′-(9- anthracenyl)-2,2′-bithiophene (1), 5-(2′,3′,4′,5′-tetraphenyl)phenyl-5′-(1-pyrenyl)-2,2′ -bithiophene (2), and 5-(2′,3′,4′,5′-tetraphenyl)phenyl-5′-(1-pyrenylethynyl)-2,2′- bithiophene (3). Thermogravimetric analysis and differential scanning calorimetry suggest that unsymmetrical dendrimers 1 and 2 have good thermal stability (>400 °C) and high glass transition temperature (>130 °C) which make them promising candidates for highly stable organic light-emitting devices. The comparative study on their UV−vis absorption and fluorescence spectra in solution and as thin films indicates that the unsymmetrical dendrimers can form intermolecular π−π stacking in the solid state. Electroluminescence (EL) devices using them as emitters were made, and it was found that they emit intense green light, and the maximum luminance was 8659 cd/m2 at 13.5 V with a maximum efficiency of 4.9 cd/A for 1. The further comparative study on the EL performance of 1−3, combined with their single crystal structures, demonstrated that with felicitously chosen π-conjugated chromophores and better control of the space between the chromophore and dendron highly efficient light-emitting materials will be realized.
07/2008;
-
[show abstract]
[hide abstract]
ABSTRACT: A new series of ladder-type heteroacenes containing both pyrrole and furan rings, 5,6-disubstituted diindolo[3,2-b:4,5-b']thiophenes (DITs), were effectively synthesized from N-functionalized 3,3'-dibromo-2,2'-biindoles undergoing intramolecular cyclization with bis(phenylsulfonyl) sulfide and organolithium. Single-crystal X-ray results demonstrate that 5,6-dipropyldiindolo[3,2-b:4,5-b']thiophene (4b) forms a herringbone-type of packing motif and 5,6-di(p-tolyl)diindolo[3,2-b:4,5-b']thiophene (4d) forms a parallel packing motif. Both of them have S-S contacts, enhancing the electronic transport between molecules. Their photophysical properties suggest that the skeleton of diindolo[3,2- b:4,5-b']thiophene is more favorable to aggregate in solid than that of indolo[3,2-b]carbazole. The large band gaps and low-lying HOMO energy levels could result in much better stability.
The Journal of Organic Chemistry 07/2008; 73(12):4638-43. · 4.45 Impact Factor
-
06/2008;
-
Xike Gao, Wenfeng Qiu,
Xiaodi Yang,
Yunqi Liu,
Ying Wang,
Hengjun Zhang,
Ting Qi,
Ying Liu,
Kun Lu,
Chunyan Du,
Zhigang Shuai,
Gui Yu,
Daoben Zhu
[show abstract]
[hide abstract]
ABSTRACT: N,N'-Bis(n-octyl)-2,3,6,7-tetrabromonaphthalene diimide (TBNDI) was synthesized by a new imidization reaction and characterized by HRMS, (1)H NMR, (13)C NMR, elemental analyses, FT-IR, UV-vis, and single-crystal X-ray analysis. The TBNDIs are the key precursors for the synthesis of core-tetrasubstituted-naphthalene diimides.
Organic Letters 10/2007; 9(20):3917-20. · 5.86 Impact Factor
-
Xike Gao,
Ying Wang,
Xiaodi Yang,
Yunqi Liu, Wenfeng Qiu,
Weiping Wu,
Hengjun Zhang,
Ting Qi,
Ying Liu,
Kun Lu,
Chunyan Du,
Zhigang Shuai,
Gui Yu,
Daoben Zhu
[show abstract]
[hide abstract]
ABSTRACT: A new class of organic species, dibenzotetrathiafulvalene bisimides (see figure), were designed and synthesized by using a facile and general synthetic strategy. The new bisimides possess a diverse library of derivatives with various functionalities at the imide rings, and they show promise for use in a range of organic electronic applications.
Advanced Materials. 01/2007; 19(19):3037-+.
-
[show abstract]
[hide abstract]
ABSTRACT: A new series of organic-light-emitting materials, 6,7-dimethyl-2,3-di-(4‘-diphenylamino-biphenyl-4-yl)-quinoxaline (MAPQ), 6,7-dimethyl-2,3-di-[4-(9,9-dibutyl-9H-fluoren-2-yl)-phenyl]-quinoxaline (MFPQ), 2,3-dicyano-5,6-di-[4-(9,9-dibutyl-9H-fluoren-2-yl)-phenyl]-pyrazine (CFPP), and 6,7-dicyano-2,3-di-[4-(9,9-dibutyl-9H-fluoren-2-yl)-phenyl]-quinoxaline (CFPQ), have been synthesized in high yields and fully characterized. These compounds have high thermal stability and show bright-light-emission varying from blue to green owing to the different strengths of the donor and acceptor. Moreover, good reversible oxidation or reduction waves were observed except for compound MFPQ due to the potential limitation of the solvent we used, which suggests these compounds have potential applications for hole/electron transportation. Organic light-emitting diodes were fabricated in a facile nondoped configuration based on these materials. Compared to MFPQ, CFPP, and CFPQ, the higher lying HOMO level of MAPQ facilitates more efficient hole injection/transport and a higher charge-recombination rate; thus, the device based on MAPQ shows the highest luminous efficiency. For compounds CFPP and CFPQ, the LUMO levels are obviously decreased because of the incorporation of electron-accepting cyano group, so the devices based on these two compounds display better electron transportation/injection properties and better performances than those of MFPQ. These results demonstrate that high-performance light-emitting devices can be achieved from intramolecular charge-transfer emission.
12/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: Three new linear benzene-fused bis(tetrathiafulvalene) compounds (1-3) were easily synthesized by one-step phosphite-induced cross-coupling reactions; a solution processed organic field-effect transistor based on 2 shows high mobility of 0.02 cm2/Vs.
Chemical Communications 08/2006; · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Four X-shaped oligothiophenes with different conjugation length were investigated as novel electron donors in single-layer bulk-heterojunction solar cells. The UV-vis absorption spectra of blends of compounds 1-4 with 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C(61) show a remarkably red shift and broadening with increasing thiophene number at each of the four branches. The performance of the photovoltaic cells varied significantly with molecular structures of the four oligothiophenes. Conversion efficiencies increased from 0.008% to 0.8% with changing the electron donors from 1 to 4. The maximum incident photon-to-current conversion efficiency of the device based on 4 reaches 31.6%, much higher than those of three other compounds 1-3. Remarkable improvement of the device performance was achieved with increasing the substituted thiophene number. The results show that the photovoltaic effect is dependent on the structural characteristics and the film forming abilities of the X-shaped thiophenes.
The Journal of Physical Chemistry B 05/2006; 110(15):7702-7. · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: 1,6,7,12-Tetrabromoperylene-3,4,9,10-tetracarboxylic acid bisanhydride and the corresponding tetrabrominated perylene bisimide were first synthesized with high yields. The Suzuki coupling reaction of novel tetrabromoperylene bisimide with phenylbonoric acid was studied. The four bromines in the bay position of the perylene core were substituted successfully to yield 1,6,7,12-teraphenylperylene bisimide. The photochemical properties of the novel perylene bisimides were studied and presented.
Organic Letters 04/2006; 8(5):867-70. · 5.86 Impact Factor
-
Hengjun Zhang,
Ying Wang,
Kuizhan Shao,
Yunqi Liu,
Shiyan Chen, Wenfeng Qiu,
Xiaobo Sun,
Ting Qi,
Yongqiang Ma,
Gui Yu,
Zhongmin Su,
Daoben Zhu
[show abstract]
[hide abstract]
ABSTRACT: Novel butterfly pyrene derivatives functionalized with trifluoromethylphenyl and thienyl aromatic groups in the 1-, 3-, 6- and 8-positions of pyrene cores and have been synthesized by Suzuki coupling reactions, and their crystal structures, optical and electrochemical properties investigated; additionally, the field effect transistor using as the active material exhibited a p-type performance.
Chemical Communications 03/2006; · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Three new linear benzene-fused bis( tetrathiafulvalene) compounds ( 1 - 3) were easily synthesized by one-step phosphite-induced cross-coupling reactions; a solution processed organic field-effect transistor based on 2 shows high mobility of 0.02 cm(2)/Vs.
Chemical Communications. 01/2006;
-
Kai Xiao,
Yunqi Liu,
Ting Qi,
Wei Zhang,
Fang Wang,
Jianhua Gao, Wenfeng Qiu,
Yongqiang Ma,
Guanglei Cui,
Shiyan Chen,
Xiaowei Zhan,
Gui Yu,
Jingui Qin,
Wenping Hu,
Daoben Zhu
[show abstract]
[hide abstract]
ABSTRACT: We present the synthesis and characterization of a fused-ring compound, dithieno[2,3-d:2',3'-d']thieno[3,2-b:4,5-b']dithiophene (pentathienoacene, PTA). In contrast to pentacene, PTA has a larger band gap than most semiconductors used in organic field-effect transistors (OFETs) and therefore is expected to be stable in air. The large pi-conjugated and planar molecular structure of PTA would also form higher molecular orders that are conductive for carrier transport. X-ray diffraction and atomic force microscopy experiments on its films show that the molecules stack in layers with their long axis upright from the surface. X-ray photoelectron spectroscopy suggests that there are no chemical bonds at the PTA/Au interface. OFETs based on the PTA have been constructed, and their performances as p-type semiconductors are also presented. A high mobility of 0.045 cm(2)/V s and an on/off ratio of 10(3) for a PTA OFET have been achieved, demonstrating the potential of PTA for application in future organic electronics.
Journal of the American Chemical Society 10/2005; 127(38):13281-6. · 9.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Four donor-acceptor functionalized molecular materials with symmetrical structures have been synthesized and investigated for their use in optoelectronic applications. These pi-conjugated molecules consist of one electron-donating moiety, for instance, carbazole, triphenylamine, or phenothiazine at the center, and two acceptors at each side. Introduction of different donor moieties decreases the band gaps allowing a fine-tuning of the optical and electrical properties. These materials exhibit multifunctional properties, such as a red light-emitting behavior and a large photovoltaic effect. Red organic light-emitting diodes were fabricated in a facile nondoping configuration based on these materials. Saturated red-emission is observed with a CIE of x = 0.64 and y = 0.33, and an external quantum efficiency of 0.19%. In addition, our first observation of photovoltaic response in the pi-conjugated molecule with donor-acceptor-donor structure is reported. The organic single-component photovoltaic cells were fabricated and characterized. Their open-circuit voltage and short-circuit current density are 1.1 V and 0.07 mA cm(-2), respectively. The photovoltaic effect corresponds to the absorption characteristics of the compound and depends on the nature of the electron-donating group.
The Journal of Physical Chemistry B 07/2005; 109(21):10786-92. · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The novel perylene bisimides functionalized with oligothiophene substituents in the bay position of the perylene core N,N‘-di(2-ethylhexyl)-1,7-di(thiophen-2-yl)perylene-3,4,9,10-tetracarboxylic acid bisimide (2a), N,N‘-di(2-ethylhexyl)-1,7-di[(2,2‘)bithiophen-5-yl]perylene-3,4,9,10-tetracarboxylic acid bisimide (2b), and N,N‘-di(2-ethylhexyl)-1,7-di[(2,2‘;5‘,2‘ ‘)terthiophen-5-yl]perylene-3,4,9,10-tetracarboxylic acid bisimide (2c) have been synthesized and fully characterized. As compared to the unsubstituted perylene bisimide (3), the UV−vis absorptions of 2a−c undergo a bathochromic shift along with considerable band broadening and a less pronounced vibronic fine structure. Moreover, efficient intramolecular electron transfer between the oligothiophene-donor and perylene-acceptor leads to remarkable fluorescence quenching of the perylene core. Cyclic voltammetry measurements of these compounds were performed and corresponding polymers from the monomers 2b and 2c were prepared by electrochemical polymerization. Both oligomers and polymers possess a facile reductive process, and their oxidation potential can be tuned by variation of the number of thiophene groups. These properties make them promising materials for optoelectrical devices such as molecular switches, solar energy harvesters, and supercapacitors for energy storage.
03/2005;
-
[show abstract]
[hide abstract]
ABSTRACT: The third-order optical non-linearity of a Diels–Alder adduct of fullerene C60 with a copper phthalocyanine was investigated using the femtosecond time-resolved optical Kerr gate method at 830 nm wavelength. Its non-resonant second-order hyperpolarizability was estimated to be 5.4×10−31 esu. The non-linearity enhancement from the formation of the intramolecular charge-transfer complex is discussed.
Chemical Physics Letters 324:354-358. · 2.34 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Three substituted phthalocyanines (Pcs), two asymmetrical and one symmetrical, named amino-tri-tert-butyl-phthalocyanine (AmBuPc), 1,8-naphthalimide-tri-tert-butyl-phthalocyanine (NaBuPc), and tetra-iso-propoxy-phthalocyaninato copper(II) (i-Pro-CuPc), were used as semiconductor layers in organic field-effect transistors (OFETs) based on their Langmuir–Blodgett (LB) films. These substituted Pcs possess good solubility in common organic solvents. From the long-wavelength absorption edge of their UV–VIS absorption spectra and their electrochemical data, the highest occupied molecular orbital and the lowest unoccupied molecular orbital were determined and the energy band diagram of their OFETs was deduced. The narrower energy gaps of them indicated stronger electron donor–acceptor ability than other symmetrical Pcs because of the substituents at the peripheral ring. The results of their OFETs demonstrated that the LB films of these substituted Pcs can be used as semiconducting layers of OFETs functioned as p-channel accumulation devices. From the electrical characteristics of their OFETs, the channel carrier mobilities of AmBuPc, NaBuPc and i-Pro-CuPc were calculated to be about 2.84×10−5, 4.42×10−4 and 3.25×10−4 cm2 V−1 s−1, respectively.
Sensors and Actuators B: Chemical.
-
[show abstract]
[hide abstract]
ABSTRACT: A new phthalocyanine, tetra-{4-[5-(4-tert-butyl-phenyl)-[1,3,4]oxadiazol-2-yl]-phenoxy}-zincphthalocyanine (TOPc) was synthesized and its Langmuir–Blodgett (LB) film was fabricated and characterized by ultraviolet–visible (UV–vis) absorption and polarized UV–vis absorption spectra. The results show that the tilt angle of TOPc molecules on substrate is about 32°. Field-effect transistor incorporating with LB film of TOPc as a semiconductor layer was fabricated. A mobility of 1.1 × 10−4 cm2 V−1 s−1 and an on/off ratio up to 103 have been achieved.
Synthetic Metals.
