The Experts below are selected from a list of 801 Experts worldwide ranked by ideXlab platform
Ben Zhong Tang - One of the best experts on this subject based on the ideXlab platform.
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Surface Effect on the Self-Assembly of Nanofibers Revealed by in Situ AFM Imaging and Molecular Simulation
2019Co-Authors: Yantao Chen, Shan Xue, Qing Xia, Qiuming Liu, Ben Zhong TangAbstract:Conventional imaging techniques, such as scanning electron microscopy, transmission electron microscopy, and atomic force microscopy (AFM), have the same sample preparation, that samples are added dropwise on the substrate. It is not known whether the observed assemblies are formed exclusively in solution or subsequently assembled on the substrate surface. In this work, with an amino acid-containing Silole molecule (Silole-leu) as the ideal model system, we demonstrated that the assembly can be directly formed on the surface of mica. Real time and influence AFM imaging revealed the epitaxial growth of nanofibers during the evaporation of solvent. The highly oriented nanofibers intercrossed with each other at the angle of 60 or 120°, matching well with the underlying crystal lattice of mica. Prolonged evaporation of samples in the microchannel resulted in the formation of more aligned fibers. Molecular simulations showed that Coulomb interactions between the substrate and sample stretched Silole-leu into an extensively expanded conformation. The joint effort from hydrogen bonding, π–π interactions between Silole-leu molecules, and Coulomb interactions guided the nucleation and propagation of nanofibers. Our study revealed that the surface effect was nontrivial even for the samples in the evaporation state, which deserved more attention for understanding the morphologies of samples and revealing the principles of assemblies
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click synthesis aggregation induced emission and chirality circularly polarized luminescence and helical self assembly of a leucine containing Silole
Small, 2016Co-Authors: Shan Xue, Jacky Wing Yip Lam, Kam Sing Wong, Bo Shen, Zhihui Cheng, Ben Zhong TangAbstract:By introducing chiral leucine pendants to Silole scaffold, leucine-containing Silole (Silole-Leu) is synthesized and it is endowed with not only aggregation-induced emission and circular dichroism, but excellent chiral polarized luminescence as well. Silole–Leu also has the capacity to self-assemble into nano/micro helical luminescent fibers and the dimension of the fibers can be tuned by adjusting the ratio and volume of mixed solvents for evaporation as revealed by atomic force microscope, scanning electron microscope, and fluorescence microscope. The characteristic helicity of microfibers is directly visualized for the first time by using fluorescence microscope.
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Synthesis and High Solid-State Fluorescence of Cyclic Silole Derivatives
2015Co-Authors: Yuanjing Cai, Ben Zhong Tang, Kerim Samedov, Brian S Dolinar, Zhegang Song, Chaocan Zhang, Robert WestAbstract:Cyclotetrasiloxanes 1–3 containing different Silole-based fluorogenic units (silafluorene, 1,3-diphenyl-9-silafluorene, tetraphenylSilole) were synthesized by cohydrolysis and condensation reactions. Their optical properties in solution and as crystals were studied. These compounds have low quantum yields in solution (Φfl = 0.01–0.18) with fluorescence maxima at 359–375 nm for silafluorene-containing compounds 1 and 3 and at 491 nm for AEE-active tetraphenylSilole compound 2. However, 1–3 have high solid-state quantum yields (Φfl = 0.65–0.78) with fluorescence maxima at 377–390 nm for compounds 1 and 3 and at 517 nm for tetraphenylSilole- and silafluorene-containing compound 2. Packing analysis of 1–3 in the crystal structure and MO and excited-state calculations were performed to explore possible fluorescence mechanisms in these compounds
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a visual film sensor based on Silole infiltrated sio2 inverse opal photonic crystal for detecting organic vapors
Journal of Materials Chemistry C, 2014Co-Authors: Yuqi Zhang, Ben Zhong Tang, Jianhua Qiu, Loujun Gao, Liping Heng, Miaomiao Gao, Lei JiangAbstract:The reversible color change of the Silole-infiltrated SiO2 inverse opal photonic crystal (IOPC) film can be obtained by alternating its exposure to different vapor environments. When the film was put in diethyl ether or petroleum ether vapor, a stopband red shift of more than 100 nm could be clearly observed, while the color changed from green to red. When exposed to air, the stopband underwent a blue shift and the color changed back to green. The result is attributed to the Silole molecules, hexaphenylSilole (HPS), which can be transformed reversibly between the crystal and amorphous state when alternately exposed to air and vapors of diethyl ether/petroleum ether. When crystal HPS changed to amorphous HPS in an atmosphere of organic vapors, both the specific surface area and refractive index of HPS increased. The higher specific surface area of HPS improved the adsorption behavior of organic vapors. Both the improved adsorption and higher refractive index of HPS increased the effective refractive index of HPS-infiltrated SiO2 IOPC, which resulted in the red shift of the stopband and the color change, according to the Bragg Law. Based on the reversible aggregation state transfer and the adsorption–desorption of organic vapors, the effective refractive index of the film varied repeatedly, which caused the reversible stopband shift and color change. The visual detection of organic vapors can be realized because of the remarkable color change of the IOPC film, which provides a simple route for monitoring volatile organic compounds, and is important for chemical and biological sensors.
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valine containing Silole synthesis aggregation induced chirality luminescence enhancement chiral polarized luminescence and self assembled structures
Journal of Materials Chemistry C, 2014Co-Authors: Qin Yuan, Jianzhao Liu, Chunhua Liu, Xiaolin Fan, Ben Zhong TangAbstract:The synthesis of valine-containing Silole is reported. The introduction of a chiral valine pendant to Silole endows the new compound (1 in Scheme 1) with not only circular dichroism (CD) and chiral-polarized luminescence (CPL), but also an aggregation-induced emission (AIE) property. The AIE effect boosts the fluorescence quantum efficiency, ΦF, from 0.33% in pure THF to a maximum of 18.9% when water is added, which is 57 times higher than that in pure THF. In the thin film state, the ΦF value measured by a calibrated integrating sphere can reach 80.3%, which is 243 times higher than that in the solution state. The amphiphilic valine attachments enable the compound to aggregate into complex architectures by a self-assembling process as revealed by AFM images. This compound self-assembles into helical fibers on the evaporation of its THF solution, which corresponds well with its CD and CPL properties. The addition of a poor solvent such as water or hexane to the THF solution also leads to the formation of aggregated structures, which exhibit helical enhancement or inversion in handedness to different extents.
Yang Yang - One of the best experts on this subject based on the ideXlab platform.
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silicon atom substitution enhances interchain packing in a thiophene based polymer system
Advanced Materials, 2010Co-Authors: Hsiangyu Chen, Jianhui Hou, Amy E Hayden, Hoichang Yang, K N Houk, Yang YangAbstract:A new Silole-containing low bandgap polymer is synthesized by replacing the 5-position carbon of PCPDTBT with a silicon atom (PSBTBT). Through experiments and computational calculations, we show that the material properties, particular the packing of polymer chains, can be altered significantly. As a result, the polymer changes from amorphous to highly crystalline with the replacement of the silicon atom.
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low band gap dithieno 3 2 b 2 3 d Silole containing polymers synthesis characterization and photovoltaic application
Chemical Communications, 2009Co-Authors: Lijun Huo, Hsiangyu Chen, Jianhui Hou, Teresa L Chen, Yang YangAbstract:A series of low band gap Silole-containing polymers were synthesized with different alkyl side chains and a power conversion efficiency (PCE) of 3.43% was obtained.
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synthesis characterization and photovoltaic properties of a low band gap polymer based on Silole containing polythiophenes and 2 1 3 benzothiadiazole
Journal of the American Chemical Society, 2008Co-Authors: Jianhui Hou, Hsiangyu Chen, Shaoqing Zhang, Yang YangAbstract:A new low band gap Silole-containing conjugated polymer, PSBTBT, was designed and synthesized. Photovoltaic properties of PSBTBT were initially investigated, and an average power conversion efficiency (PCE) of 4.7% with a best PCE of 5.1% was recorded under illumination (AM 1.5G, 100 mW/cm(2)). The response range of the device covers the whole visible range from 380 to 800 nm. These results indicate that PSBTBT is a promising polymer material for applications in polymer solar cells.
Guillermo C Bazan - One of the best experts on this subject based on the ideXlab platform.
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end capping effect of a narrow bandgap conjugated polymer on bulk heterojunction solar cells
Advanced Materials, 2011Co-Authors: Jin Kuen Park, Jang Jo, Ji Sun Moon, Yeong Don Park, Alan J Heeger, Guillermo C BazanAbstract:Device performances of BHJ solar cells based on poly[(4,4-didodecyldithieno[3,2-b:2’,3’-d]Silole)-2,6-diyl-alt-(2,1,3-benzoxadiazole)-4,7-diyl]and PC₇₁BM improve by capping the chain ends with thiophene fragments. This structural modification yields materials that are more thermally robust and that can be used in devices with thicker films – important considerations for enabling the mass production of plastic solar cells.
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improved performance of polymer bulk heterojunction solar cells through the reduction of phase separation via solvent additives
Advanced Materials, 2010Co-Authors: Corey V Hoven, Jeff Peet, Xuandung Dang, Robert C Coffin, Thucquyen Nguyen, Guillermo C BazanAbstract:A high-boiling-point additive that favors both poly[(4,4-didodecyldithieno[3,2-b:2',3'-d]Silole)-2,6-diyl-alt-(2,1,3-benzoxadiazole)-4,7-diyl] and PC₇₁BM in a bulk heterojunction solar cell is used to reduce large-scale aggregation and phase separation, which increases device performance. This is in contrast to the majority of high-boiling-point additives that improve performance by increasing phase separation.
Xiaowei Zhan - One of the best experts on this subject based on the ideXlab platform.
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synthesis electron mobility and electroluminescence of a polynorbornene supported Silole
Polymer, 2009Co-Authors: Xiaowei Zhan, Andreas Haldi, Takeshi Kondo, Benoit Domercq, Jianyang Cho, Stephen Barlow, Bernard Kippelen, Seth R MarderAbstract:Abstract A solution-processable polynorbornene with pendant fluorescent and electron-transport Silole groups was synthesized using ruthenium-complex-initiated ring-opening metathesis polymerization. A weight-average molecular weight around 59,300 and a low polydispersity index of 1.4 were estimated for the polymer using gel permeation chromatography. The thermal, electronic, photo- and electroluminescence properties of the polymer were investigated and compared with those of a small-molecule reference compound. The polymer exhibits better thermal stability than the small molecule and exhibits a glass transition temperature of 91 °C, while retaining the optical and electronic properties of the corresponding small-molecule Silole. The room temperature electron mobility was measured using the time-of-flight technique to be 3.5 × 10 −5 cm 2 /V/s at an applied electric field of 7.5 × 10 5 V/cm. Organic light-emitting diodes fabricated using the polymer as the electron transport and emissive layer have low efficiencies; introduction of an additional tris(8-hydroxyquinolinato)aluminum (Alq 3 ) electron-transport layer leads not only to increased efficiency, but also to increased contributions to the electroluminescence from the Alq 3 .
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structures electronic states photoluminescence and carrier transport properties of 1 1 disubstituted 2 3 4 5 tetraphenylSiloles
Journal of the American Chemical Society, 2005Co-Authors: Shiwei Yin, Ben Zhong Tang, Daoben Zhu, Xiaowei Zhan, Yunqi Liu, Jiangshan Chen, Xiaobo Sun, Qian Peng, Zhigang Shuai, Weihai FangAbstract:The excellent electroluminescent (EL) properties of 1,1-disubstituted 2,3,4,5-tetraphenylSiloles, 1-methyl-1,2,3,4,5-pentaphenylSilole (MPPS), and 1,1,2,3,4,5-hexaphenylSilole (HPS) have been found. Despite some studies devoted to these materials, very little is known about the real origin of their unique EL properties. Therefore, we investigated the structures, photoluminescence (PL), and charge carrier transport properties of 1,1-disubstituted 2,3,4,5-tetraphenylSiloles as well as the effect of substituents on these characteristics. The single crystals of the three Siloles involving 1,1-dimethyl-2,3,4,5-tetraphenylSilole (DMTPS), MPPS, and HPS were grown and their crystal structures were determined by X-ray diffraction. Three Siloles have nonplanar molecular structures. The substituents at 1,1-positions enhance the steric hindrance and have predominant influence on the twisted degree of phenyl groups at ring carbons. This nonplanar structure reduces the intermolecular interaction and the likelihood of e...
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aggregation induced emission of 1 methyl 1 2 3 4 5 pentaphenylSilole
Chemical Communications, 2001Co-Authors: Lin Cheng, Hoi Sing Kwok, Haiying Chen, Xiaowei Zhan, Ben Zhong TangAbstract:Aggregation greatly boosts emission efficiency of the Silole, turning it from a weak luminophor into a strong emitter.
Attila J Mozer - One of the best experts on this subject based on the ideXlab platform.
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reduced bimolecular recombination in conjugated polymer donor fullerene acceptor bulk heterojunction solar cells
Australian Journal of Chemistry, 2012Co-Authors: Attila J Mozer, Tracey M. ClarkeAbstract:We show significantly reduced bimolecular recombination in a novel Silole-based copolymer (KP115):fullerene blend, which allows the fabrication of polymer solar cells with relatively thick active layers. This leads to improved device efficiencies and makes roll-to-roll printing much easier. The origin of the reduced recombination, however, is not known. Our recent data suggest that published models are inadequate to explain this phenomenon.
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Non-Langevin bimolecular recombination in a Silole-based polymer:PCBM solar cell measured by time-resolved charge extraction and resistance-dependent time-of-flight techniques
Energy Environ. Sci., 2012Co-Authors: Tracey M. Clarke, Christoph Lungenschmied, Patrick Denk, Gilles Dennler, Jeff Peet, Attila J MozerAbstract:The Silole-based non-Langevin conjugated polymer KP115 has been used to demonstrate that circuit resistance is a crucial parameter in time-of-flight measurements of organic photovoltaic cells, providing a resistance-dependent bimolecular recombination coefficient. The origin of this behaviour is the biphasic decay dynamics present in KP115:PCBM devices (observed using a novel time-dependent charge extraction technique), which time-of-flight cannot accurately characterise.
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Reduced Bimolecular Recombination in Conjugated Polymer Donor/Fullerene Acceptor Bulk Heterojunction Solar Cells
Australian Journal of Chemistry, 2012Co-Authors: Attila J Mozer, Tracey M. ClarkeAbstract:We show significantly reduced bimolecular recombination in a novel Silole-based copolymer (KP115):fullerene blend, which allows the fabrication of polymer solar cells with relatively thick active layers. This leads to improved device efficiencies and makes roll-to-roll printing much easier. The origin of the reduced recombination, however, is not known. Our recent data suggest that published models are inadequate to explain this phenomenon.