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ABSTRACT: Insights into the origin of the fluorescence responsive to protonation-deprotonation stimuli were provided through the study on the crystals of a new stimuli-responsive molecule BP3VA. And the transformation between microcrystals demonstrated the varying emissions of the BP3VA powder.
Chemical Communications 04/2013; · 6.17 Impact Factor
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ABSTRACT: The electronic structure and charge transport property of 9,10-distyrylanthracene (DSA) and its derivatives with high solid-state luminescent efficiency were investigated by using density functional theory (DFT). The impact of substituents on the optimized structure, reorganization energy, ionization potential (IP) and electronic affinity (EA), frontier orbitals, crystal packing, transfer integrals and charge mobility were explored based on Marcus theory. It was found that the hole mobility of DSA was 0.21 cm(2) V(-1) s(-1) while the electron mobility was 0.026 cm(2) V(-1) s(-1), which were relatively high due to the low reorganization energies and high transfer integrals. The calculated results showed that the charge transport property of these compounds can be significantly tuned via introducing different substituents to DSA. When one electron-withdrawing group (cyano group) was introduced into DSA, DSA-CN exhibited hole mobility of 0.14 cm(2) V(-1) s(-1) which was on the same order of that of DSA. However, the electron mobility of DSA-CN decreased to 8.14 × 10(-4) cm(2) V(-1) s(-1) due to the relatively large reorganization energy and disadvantageous transfer integral. The effect of electron-donating substituents was investigated by introducing methoxy group and tertiary butyl into DSA. DSA-OCH(3) and DSA-TBU showed much lower charge mobility than DSA resulting from the steric hindrance of substituents. On the other hand, both of them exhibited balanced transport properties (for DSA-OCH(3), the hole and electron mobility was 0.0026 and 0.0027 cm(2) V(-1) s(-1); for DSA-TBU, the hole and electron mobility was 0.045 and 0.012 cm(2) V(-1) s(-1)) because of their similar transfer integrals for both hole and electron. DSA and its derivatives were supposed to be one of the most excellent emissive materials for organic electroluminescent applications because of their high charge mobility and high solid-state luminescent efficiency.
Physical Chemistry Chemical Physics 01/2013; · 3.57 Impact Factor
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ABSTRACT: A donor-acceptor (D-A) type indoline dye, D149, was used as an electron donor in solution-processed organic solar cells (OSCs). For bulk-heterojunction (BHJ) type OSCs with PCBM as electron acceptor, the power conversion efficiency (PCE) is sensitive to the amount of D149 in the D149/PCBM blend film. When the concentration of D149 in the blend film was as low as 5%, the highest PCE of up to 1.29%, together with a short-circuit current density (Jsc) of 4.58 mA·cm-2, an open-circuit voltage (Voc) of 0.90 V and a fill factor (FF) of 0.31, was achieved. In order to improve the PCE of D149-based OSCs, a bilayer-heterojunction configuration with C as electron acceptor has been employed. By optimizing the thickness of the D149 layer and varying the electron- and hole-transport layers, a highest PCE of up to 2.28% with a Jsc of 4.38 mA·cm-2, a Voc of 0.77 V, and an FF of 0.62 was achieved under AM 1.5G solar illumination (100 mW·cm-2).
Molecules 01/2013; 18(3):3107-17. · 2.39 Impact Factor
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Yujie Dong,
Bin Xu,
Jibo Zhang,
Xiao Tan,
Lijuan Wang,
Jinlong Chen,
Hongguang Lv,
Shanpeng Wen,
Bao Li,
Ling Ye,
Bo Zou, Wenjing Tian
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ABSTRACT: A chameleon under pressure: The observed piezochromic behavior of the title compound (BP2VA) was found to depend on its molecular aggregation state and specifically on the strength of the π-π interaction between the anthracene rings of adjacent molecules. When BP2VA is ground or placed under pressure, its molecular aggregation state changes, and a red shift in the fluorescence emission from green via orange to red occurs.
Angewandte Chemie International Edition 09/2012; 51(43):10782-5. · 13.45 Impact Factor
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ABSTRACT: Electrochemistry provides a simple and promising method for preparing organic solar cells (OSCs). In this paper, we present
a two-step solution-based method to prepare bilayer heterojunction OSCs by electrodepositing polythiophene (PTh) and then
spin-coating chloroform solution of [6,6]-phenyl C61-butyric acid methyl ester (PCBM) onto the PTh layer. The influence of
film thickness on performance of bilayer solar cells was investigated, and the best performance was achieved when the thickness
of PTh and PCBM was 15nm and 30nm, respectively. The optimized solar cell showed power conversion efficiency of 0.1% under
the illumination of AM 1.5 (100mWcm−2) simulated solar light. This solution-based method offers a new way for processing bilayer OSCs.
KeywordsElectrodeposition-Organic solar cells-Polythiophene-Spin coating
Journal of Solid State Electrochemistry 04/2012; 14(6):1051-1056. · 2.13 Impact Factor
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ABSTRACT: The biological impact of engineered nanomaterials released into the aquatic environment is a major concern. In this work,
the properties of ZnO nanoparticles (nano-ZnO, 30nm) were characterized in a water suspension (E3 medium), and a zebrafish
96-h post fertilization (hpf) embryo–larval test was performed to assess the toxicity of nano-ZnO suspension. Nano-ZnO was
found to readily form aggregates with different sizes; small aggregates (142.4–517.7nm) were still suspended in E3 medium,
but large aggregates (>1μm) quickly deposited on the bottom of 24-well plates; nano-ZnO was partially dissolved to Zn species
(Zn(dis)) in E3 medium. In the nano-ZnO suspension, small aggregates, Zn(dis), and large aggregates might jointly exert influence on the development of zebrafish embryos. The embryo toxicity test revealed
that nano-ZnO killed zebrafish embryos (50 and 100mg/L), retarded the embryo hatching (1–25mg/L), reduced the body length
of larvae, and caused tail malformation after the 96hpf exposure. Zn(dis) only partially contributed to the toxicity of nano-ZnO. This research highlights the need to further investigate the ecotoxicity
of nano-ZnO in the water environment.
KeywordsZnO nanoparticles-Solubility-Aggregate-Toxicity-Zebrafish embryo-Environment-EHS
Journal of Nanoparticle Research 04/2012; 12(5):1645-1654. · 3.29 Impact Factor
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ABSTRACT: Poly(1,4-naphthalenevinylene), prepared from a water-soluble precursor, was used to fabricate hybrid solar cells by blending with water-soluble CdTe nanocrystals (NCs) to act as the photoactive layer. In composites with CdTe NCs as the electron acceptors in a bulk heterojunction configuration, the devices exhibited a short-circuit current density of -6.14 mA/cm(2), an open-circuit voltage of 0.44 V, a fill factor of 0.32, and a power conversion efficiency of 0.86% under AM1.5G conditions. Because the devices were fabricated from water-soluble materials, the procedure was generally simple and environmentally friendly in comparison to the conventional devices fabricated from oil-soluble materials.
ACS Applied Materials & Interfaces 07/2011; 3(8):2919-23. · 4.53 Impact Factor
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ABSTRACT: Conjugated oligocarbazoles with a 9,10-divinylanthracene core have been synthesized, and exhibit the transition from aggregation-induced emission (AIE) to aggregation-induced emission enhancement (AIEE) behaviour with extending conjugation length; self-assembly of the Cz4 molecule affords nanorings with high fluorescent efficiency.
Chemical Communications 06/2011; 47(23):6602-4. · 6.17 Impact Factor
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ABSTRACT: Four diboron-bridged ladder molecules 1-4 have been designed and synthesized. X-ray diffraction analysis revealed that the bulky phenyl substituents on boron centers efficiently prevented π stacking of the luminescent ladder unit. Characterizations of these complexes demonstrated that the construction of diboron-containing ladder-type skeletons endowed these materials with good thermal stability, high fluorescence quantum yields, and strong electron affinity. The highly efficient nondoped organic light-emitting diodes using complexes 1 and 2 as electron-transporting emitters exhibited maximum luminance values of 16,930 and 18,060 cd/m(2) with turn-on voltages of 3.5 and 2.5 V as well as maximum luminous efficiencies of 6.4 and 5.4 cd/A, respectively.
Inorganic Chemistry 06/2011; 50(11):4825-31. · 4.60 Impact Factor
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ABSTRACT: In this paper, we demonstrated a modified hot-injection method to synthesize high-quality Cu2–xSe nanocrystals (NCs) in liquid paraffin without using the hazardous and unstable alkylphosphines as the ligand of Se. The key of this method is the capability for tuning the reactivity of Se at the stage of formation of Cu2–xSe nuclei. The low reactivity of Se facilitated the decomposition of copper(II) acetylacetonate into Cu2O, whereas the increase of Se reactivity promoted the reaction between Cu and Se. By control of the experimental variables, such as reaction time, Se concentration, reaction temperature, and, particularly, the addition of the noncoordinating solvent of Se, high-quality Cu2–xSe NCs were prepared. The resultant Cu2–xSe NCs possessed an indirect band-gap absorption around 1050 nm, potentially applicable in photovoltaic investigations. As an example, the optoelectronic properties of Cu2–xSe NCs were investigated, which showed a promising increase in photocurrent under AM 1.5 illumination. Because the current method was convenient and environmentally friendly, it was believed that this work would facilitate the development of a preparation technique and industrial application of copper-based photovoltaic devices.
04/2011;
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Journal of Polymer Science Part A Polymer Chemistry 04/2011; 49(12):2715 - 2724. · 3.92 Impact Factor
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ABSTRACT: A series of donor−acceptor (D−A) conjugated copolymers with benzo[1,2-b:4,5-b′]dithiophene (BDT) as donor and two different electron-accepting groups bithiophenevinyl-2-pyran-4-ylidenemalononitrile (TVM) and benzothiadiazole (BT) moieties as acceptors is designed and synthesized. The optical and electrochemical properties show that the band gaps of the copolymers are in the range of 1.70−1.84 eV, and the HOMO and LUMO energy levels can be tuned effectively by controlling the varied ratios between TVM and BT because of the change of the ICT interaction between donor and acceptor, the electron delocalization degree, and the electron cloud density distribution of the copolymers. Bulk heterojunction photovoltaic devices are fabricated by using the copolymers as donors and (6,6)-phenyl-C61-butyric acid methyl ester (PC61BM) or (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) as acceptors. The optimized photovoltaic performances show that the open-circuit voltage (Voc) was gradually increased from 0.7 to 0.94 V when decreasing the HOMO energy levels of copolymers, and the short-circuit current density (Jsc) is greatly improved by increasing the absorption spectrum in the visible region, increasing the hole mobility and optimizing the morphologies of blend films between copolymers and PCBM. The optimized photovoltaic performance with a Voc of 0.78 V, Jsc of 5.47 mA/cm2, fill factor (FF) of 0.40, and power conversion efficiency (PCE) of 1.67% under simulated AM 1.5 solar irradiation of 100 mW/cm2 is obtained by the copolymer PM50 (PM50:PC61BM, 1:3 w/w, in CB solution). This is due to its high hole mobility and interpenetrating network morphology of PM50:PC61BM blend film. The photovoltaic device based on PM50:PC71BM shows a Jsc of 8.32 mA/cm2 and a PCE of 2.89%.
01/2011;
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ABSTRACT: The environmental behavior and the potential toxicity of copper nanoparticles (nano-Cu) in water are major concerns for assessing their environmental safety. The present study was undertaken to characterize the properties of nano-Cu in E3 medium, such as size changes, solubility, zeta-potential and pH, and to test the toxicity of nano-Cu suspension to zebrafish embryos. Dynamic light scattering and solubility experiments showed that three components coexisted in the nano-Cu exposure system, including small nano-Cu aggregates still suspended in E3 medium, large nano-Cu aggregates deposited on the container bottom and dissolved copper species (Cu(dis)). Both the zeta-potential of nano-Cu particles in E3 medium and the pH of the nano-Cu suspension showed no change during a 24 hour period. It is found that nano-Cu retarded the hatching of zebrafish embryos and caused morphological malformation of the larvae, and high concentrations (>0.1 mg/L) of nano-Cu even killed the gastrula-stage zebrafish embryos. Cu2+ ions were used to study the toxicity caused by nano-Cu dissolution. The embryo toxicity of nano-Cu at 0.01 and 0.05 mg/L showed no significant difference from Cu2+ at the corresponding concentrations (0.006 and 0.03 mg/L), but 0.1 mg/L nano-Cu had a greater toxicity than 0.06 mg/L Cu2+.
Journal of Nanoscience and Nanotechnology 12/2010; 10(12):8670-6. · 1.56 Impact Factor
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ABSTRACT: The ordered [Pt(CN-tBu)(2)(CN)(2)] semiconducting microwires have been prepared on substrates based on solvent evaporation or dip-and-pull approaches and were found to display photo- and vapor-responsive conducting characteristics.
Chemical Communications 11/2010; 46(41):7727-9. · 6.17 Impact Factor
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ABSTRACT: A series of solution processable small molecules (4TPM, 6TPM, and 8TPM) were synthesized with 2-pyran-4-ylidenemalononitrile (PM) as the electron-accepting unit and oligothiophene with different numbers as the electron-donating unit. Differential scanning calorimetry (DSC) measurement indicated that melting point and crystal temperature of molecules increased with the increase of thiophene number. UV−vis absorption demonstrated that the combination of PM with oligothiophene resulted in an enhanced intramolecular charge transfer (ICT) transition, which led to an extension of the absorption of the molecules. Cyclic voltammetry investigation displayed that the highest occupied molecular orbital (HOMO) energy levels of the three molecules were relatively low, which promised good air stability and high open circuit voltage (Voc) for photovoltaic application. Theoretical calculations revealed that the variation laws of HOMO and the lowest unoccupied molecular orbital (LUMO) energy levels are well consistent with cyclic voltammetry measurement. The bulk heterojunction (BHJ) photovoltaic devices with the structure of ITO/PEDOT−PSS/small molecules−PCBM/LiF/Al were fabricated, with the three molecules as donor and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor. The device based on 6TPM/PCBM (30:70 w/w) successfully achieved a maximum power conversion efficiency (PCE) of 1.15% under the illumination of AM 1.5, 100 mW/cm2.
10/2010;
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ABSTRACT: Novel p-type materials, liquid-crystalline polyfluorene and its copolymer containing a terphenyl mesogen pendant, namely, poly{9,9-bis[6-(4′-hexyloxy-terphenyloxy)-hexyl]-fluorene} (PFBHeT) and poly{9,9-bis[6-(4′-hexyloxy-terphenyloxy)-hexyl]-fluorene-co-3-hexyl-thiophene} (PFBHeT-3HT), were designed and synthesized, respectively. The effects of the structural variation on their properties, especially the influences of the thermal treatment on the blend morphology of polymers and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), have been characterized and investigated. The spontaneous orientation of terphenyl mesogen endows the polymer and blend films with a good ordered morphology. The annealed and quenched films exhibit better liquid-crystalline properties, a lower LUMO, and better ordered domains compared with the untreated one, and the annealed films are favorable. It indicates that the spontaneous assembly of the liquid-crystalline molecules pushes PCBM clusters to form an oriented nanodispersing structure with highly oriented channel layers upon heating at liquid-crystalline states, and the annealing process offers enough stress relaxation time for the molecules to pack into a well-ordered stacking. Furthermore, the bulk heterojunction devices based on the PFBHeT-3HT:PCBM (1:2) active layer have been constructed. Without extensive optimization, annealing the devices yields a Voc of 0.63 V and a power conversion efficiency of 0.25%, showing a significantly increased Jsc and FF with respect to its untreated counterpart.
09/2010;
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Journal of Polymer Science Part A Polymer Chemistry 05/2010; 48(13):2765 - 2776. · 3.92 Impact Factor
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ABSTRACT: Three functionalized 9,10-distyrylanthracene (DSA) derivatives, namely, 9,10-bis(4-hydroxystyryl)anthracene (2), 9,10-bis{4-[2-(diethylamino)ethoxy]styryl}anthracene (4), and 9,10-bis{4-[2-(N,N,N-triethylammonium)ethoxy]styryl}anthracene dibromide (5), were synthesized and their fluorescence properties were investigated. The three DSA derivatives possess a typical aggregation-induced emission (AIE) property (i.e., they are nonluminescent in dilute solutions but are efficiently fluorescent as induced by molecular aggregation). Different AIE properties were tuned through molecular structure control. Dye 2 is a phenol-moiety-containing compound, which shows aggregation at pH values smaller than 10, resulting in a high fluorescence intensity. Thus, dye 2 has a pK(a) of 9.94. 4 is an amine-containing compound that starts to aggregate at slightly basic conditions, resulting in a pK(a) of 6.90. Dye 5 is an ammonium-salt-containing compound. Because it is very soluble in water, this compound has no AIE phenomenon but can interact strongly with protein or DNA to amplify its emission. Therefore, 5 is a fluorescent turn "on" biological probe for protein and DNA detection and it is also selective, which works for native BSA and ct DNA but not their denatured forms. Therefore, we not only developed a few new compounds showing the AIE phenomena but also controlled the AIE through environmental stimulation and demonstrated that the new AIE molecules are suitable for pH and biomacromolecule sensing.
Langmuir 05/2010; 26(9):6838-44. · 4.19 Impact Factor
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ABSTRACT: Three photovoltaic-applicable donor-acceptor (D-A) alternating copolymers including poly{(9,9-dihexyl-9H-fluorene-2,7-ylene)-alt-2-(2,6-bis((E)-2-(5-bromo-3,4-dihexylthiophen-2-yl)vinyl)-4H-pyran-4-ylidene) malononitrile} (PFTMT), poly{(10-hexyl-10H-phenothiazine-3,7-ylene)-alt-2-(2,6-bis((E)-2-(5-bromo-3,4-dihexylthiophen-2-yl)vinyl)-4H-pyran-4-ylidene) malononitrile} (PPTMT) and poly{(2,20-bithiophene-5,50-ylene)-alt-2-(2,6-bis((E)-2-(5-bromo-3,4-dihexylthiophen-2-yl)vinyl)-4H-pyran-4-ylidene)malononitrile} (PDTTMT), were blended with [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) to serve as active layers for photovoltaic applications. The effects of extrinsic (blend ratio and solvent) and intrinsic factors (donor materials) on the morphologies of this series of active layers were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). It was found that the PFTMT:PCBM active layers show distinct phase segregation with large PCBM clusters above 100 nm and are strongly affected by solvent evaporation rate in higher blend ratios. In contrast, the PPTMT:PCBM active layers are homogeneous and not affected by blend ratios and solvents, while the PDTTMT:PCBM active layers show an interpenetrating network initially formed at the blend ratio of 1:1. These results indicate that the polymer-PCBM repulsions arising from the molecular structure of the polymers play a significant role in determining the resulting morphologies of the blend films. Strong PFTMT-PCBM repulsion leads to large-scale phase segregation, while weak repulsions in PPTMT-PCBM and PDTTMT-PCBM favor small-scale phase segregation only. The best photovoltaic power conversion efficiencies are obtained from PDTTMT-based solar cells with the PDTTMT:PCBM blend ratio of 1:3 and nanoscale phase separation of the active layer, where a good balance is formed between a large donor-acceptor interface and the continuous paths of donor and acceptor phase for opposite charge carrier transport to their corresponding electrodes.
Nanotechnology 03/2010; 21(15):155201. · 3.98 Impact Factor
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ABSTRACT: Three novel conjugated copolymers containing alkoxylated 4,7-diphenyl-2,1,3-benzothiadiazole and dialkylfluorene or dialkyloxyphenylene or dialkylthiophene units were prepared by Horner polycondensation reactions. They are all soluble in common organic solvents such as chloroform, tetrahydrofuran, and chlorobenzene. The novel copolymers were characterized by NMR, GPC, and elemental analysis. Thermogravimetric analysis of the copolymers showed they have good thermal stability with the decomposition temperature higher than 350 °C. Cyclic voltammetric study shows that the HOMO energy levels of the three copolymers are deep-lying which implies that these copolymers have good stability in the air and the relatively low HOMO energy level assures a higher open circuit potential when they are used in photovoltaic cells. Bulk-heterojunction photovoltaic cells were fabricated with the copolymers as the donors and PCBM as the acceptor. The cells based on the three copolymers exhibited power conversion efficiencies of 0.65, 1.25, 1.62% with high open circuit potential of 0.76, 0.96, and 1.04 V under one sun of AM 1.5 solar simulator illumination (100 mW/cm2).
07/2009;
