Browsing by Author "Ho, Rong-Ming"

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Alkali Metal Ion-enhanced Threading of a Perylenediimide-ound Polymer Chain through a Double-stranded Spiroborate Helicate with a Bisporphyrin Unit
(2017-07-01)
Ousaka, Naoki
;
Yamamoto, Shinya
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Hayashi, Naoki
;
Li, Ming-Chia
;
Ho, Rong-Ming
Threading of a poly(ethylene glycol) (PEG) chain linked to a perylenediimide unit at one end with a bulky stopper at the other end through an inner cavity of a bisporphyrin-based double-stranded spiroborate helicate was remarkably accelerated in a specific solvent, in which the PEG chain enfolded sodium cations coordinating to the negatively charged spiroborate helicate, thus forming a 1: 1 inclusion complex with the perylenediimide sandwiched between the bisporphyrin unit.
Chirality Control and Its Memory at Microphase-Separated Interface of Self-Assembled Chiral Block Copolymers for Nanostructured Chiral Materials
(2017-09-01)
Li, Ming-Chia
;
Ousaka, Naoki
;
Wang, Hsiao-Fang
;
Yashima, Eiji
;
Ho, Rong-Ming
Here, we show the induced chirality of an achiral chromophoric dye as a joint of polylactide-containing chiral block copolymers (BCPs*) driven by self-assembly, giving the achiral dyes preferentially arranged in a one-handed helical array at the microphase-separated interface. This helical arrangement of the achiral dyes can be "memorized" after hydrolysis of the polylactides in the BCPs* and serves as a chiral template for further chirality induction of different achiral dyes, probably through attractive aromatic pi-pi interactions at the interface, producing nanostructured chiral materials with tunable circular dichroism signals at desired wavelengths.
COLL 272-Helical morphologies in the self-assembly of chiral Schiff-based rod-coil amphiphiles
(2007-08-19)
Lin, Tz-Feng
;
Ho, Rong-Ming
;
Sung, Chien-Hung
;
Hsu, Chain-Shu
;
應用化學系
Efficient inverted quasi-bilayer organic solar cells fabricated by using non-halogenated solvent processes
(2014-09-07)
Chang, Jung-Hao
;
Wang, Hsiao-Fang
;
Lin, Wei-Chieh
;
Chiang, Kai-Ming
;
Chen, Kuan-Chen
Here we demonstrate the fabrication of novel, "quasi-bilayer" inverted organic photovoltaic devices using halogen-free solvents. The inferior solubility of pristine fullerene in non-halogenated solvents was used to control the interpenetration of upper polymeric donor layers with bottom fullerene layers. Notably, island-like nano-morphologies were revealed by AFM, SEM, TEM, cross-sectional TEM images and PL quenching measurement. Correlation between device performance, thin-film nano-morphology and ac impedance was observed. High efficiencies of 6.55% and 7.15% were observed for PBDTTT-C-T and PTB7 cells, respectively. These results demonstrate that this novel process not only offers an effective new method to control the morphology of solar active layers but, more importantly, could also be applied to a wide range of current material systems to produce efficient devices that comply with the non-toxic halogen-free requirement.
Efficient inverted quasi-bilayer organic solar cells fabricated by using non-halogenated solvent processes
(2014-09-07)
Chang, Jung-Hao
;
Wang, Hsiao-Fang
;
Lin, Wei-Chieh
;
Chiang, Kai-Ming
;
Chen, Kuan-Chen
Here we demonstrate the fabrication of novel, "quasi-bilayer" inverted organic photovoltaic devices using halogen-free solvents. The inferior solubility of pristine fullerene in non-halogenated solvents was used to control the interpenetration of upper polymeric donor layers with bottom fullerene layers. Notably, island-like nano-morphologies were revealed by AFM, SEM, TEM, cross-sectional TEM images and PL quenching measurement. Correlation between device performance, thin-film nano-morphology and ac impedance was observed. High efficiencies of 6.55% and 7.15% were observed for PBDTTT-C-T and PTB7 cells, respectively. These results demonstrate that this novel process not only offers an effective new method to control the morphology of solar active layers but, more importantly, could also be applied to a wide range of current material systems to produce efficient devices that comply with the non-toxic halogen-free requirement.
Handedness of Twisted Lamella in Banded Spherulite of Chiral Polylactides and Their Blends
(2017-07-25)
Wang, Hsiao-Fang
;
Chiang, Chen-Hung
;
Hsu, Wen-Chun
;
Wen, Tao
;
Chuang, Wei-Tsung
Banded spherulite resulting from lamellar twisting due to the imbalanced stresses at opposite fold surfaces can be formed by isothermal crystallization of chiral polylactide and its blends with poly(ethylene glycol) (PEG). Using a polarized light microscope, the handedness of the twisted lamella in banded spherulite is determined. With the same growth axis along the radial direction as evidenced by wide-angle X-ray diffraction (WAXD) for isothermally crystallized samples at different temperatures, the twisted lamellae of chiral polylactides (poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA)) display opposite handedness. The split-type Cotton effect on the Co=O stretching motion of vibrational circular dichroism (VCD) spectra helps determine the helix handedness (i.e., conformational chirality). The results indicate that the conformational chirality can be defined by the molecular chirality through intramolecular chiral interactions. Moreover, the preferred sense of the lamellar twist in the banded spherulite corresponds to the twisting direction identified by the C-O-C vibration motion of VCD spectra, reflecting the role of intermolecular chiral interactions in the packing of polylactide helices. Similar results are obtained in the blends of chiral polylactides and poly(ethylene glycol) (PEG, a polymer compatible with polylactide), indicating that the impact of chirality is intrinsic irrespective of the specific crystallization conditions. In contrast to the chiral polylactides, the spectrum of the crystalline stereocomplex that associates PLLA and PDLA shows VCD silence. The spectroscopic results are in line with the morphological observations. No banded spherulites are observed in the stereocomplex crystallites due to the symmetric packing of mirror L and D-chain conformations in the fold surfaces and the crystallites core.
Helical morphologies of thermotropic liquid-crystalline chiral Schiff-based rod-coil amphiphiles
(2006-11-14)
Lin, Tz-Feng
;
Ho, Rong-Ming
;
Sung, Chien-Hung
;
Hsu, Chain-Shu
;
應用化學系
A series of Schiff-based rod-coil molecules possessing thermotropic liquid-crystalline (LC) character have been prepared whereas a sugar-based moiety was introduced to the chain end of the molecules so as to create chiral amphiphiles for self-assembly. The self-assembly of the chiral Schiff-based rod-coil amphiphiles gave rise to a variety of specific LC textures. A banded morphology under polarized light microscopy (PLM) can be observed; the appearance of the banded texture is strongly dependent upon the length of hydrophobic tail that determines the twisting power of self-assembled hierarchical superstructures with helical sense. As a result, the banded spherulites are identified as quaternary helical morphology with a collection of the tertiary chiral structures (i.e., helical twists) so as to give regular extinction in PLM attributed to zero-birefringence effect. Consistent with the observation of helical morphologies, the occurrence of chiral smectic C (SmC*) phase can only be found in samples with enough alkoxyl chain length, suggesting the existence of strong correlation for morphological evolution from molecular level to macroscopic object with the formation of SmC*. A hypothetic model about the bilayer structure within the SmC* structure is thus given to elucidate the morphological evolution. Consequently, the self-assembly of the chiral amphiphiles with thermotropic LC character represents the mechanism for the chirality transfer in different length scales.
Hierarchical Superstructures with Control of Helicity from the Self-Assembly of Chiral Bent-Core Molecules
(2012-07-01)
Lin, Shih-Chieh
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Ho, Rong-Ming
;
Chang, Chin-Yen
;
Hsu, Chain-Shu
;
應用化學系
"Herein, two asymmetric chiral bent-core molecules, 3-[(4-{[4-(heptyloxy)benzoyl]oxy}benzoyl)oxy]-phenyl-4-[(4-{[(1R)-1-methylheptyl]oxy}benzoyl)oxy] benzoate (BC7R) and 3-[(4-{[4-(heptyloxy)benzoyl]oxy}benzoyl)oxy]-phenyl-4-[(4-{[(1S)-1-methylheptyl]oxy}benzoyl)oxy] benzoate (BC7S), were synthesized to demonstrate control of the helicity of their self-assembled hierarchical superstructures. Mirror-imaged CD spectra showed a split-type Cotton effect after the formation of self-assembled aggregates of BC7R and BC7S, thereby suggesting the formation of intermolecular exciton couplets with opposite optical activities. Both twisted and helical ribbons with preferential helicity that corresponded to the twisting character of the intermolecular exciton couplet were found in the aggregates. The formation of helical ribbons was attributed to the merging of twisted ribbons through an increase in width to improve morphological stability. As a result, control of the helicity of hierarchical superstructures from the self-assembly of bent-core molecules could be achieved by taking advantage of the transfer of chiral information from the molecular level onto the hierarchical scale."
Hierarchical Superstructures with Helical Sense in Self-Assembled Achiral Banana-Shaped Liquid Crystalline Molecules
(2008-11-10)
Lin, Shih-Chieh
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Lin, Tz-Feng
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Ho, Rong-Ming
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Chang, Chin-Yen
;
Hsu, Chain-Shu
The self-assembly of 1,3-phenylene bis[4-(4-n-heptyloxybenzoyloxy)-benzoates] (BC7) is studied to examine the formation of helical morphologies from achiral banana-shaped liquid crystal molecules at different self-assembling levels. Various hierarchical superstructures including flat-elongated lamellar crystal, left- and right-handed helical ribbons, and tubular texture are observed while the BC7 molecules self-assemble in THF/H(2)O solution. By contrast, only plate-like morphology is observed in the self-assembly of achiral linear shaped 1,4-phenylene bis[4-(4-n-heptyloxybenzoyloxy)-benzoates] (LC7) molecules, indicating that the chirality of the self-assembled texture is strongly dependent upon the molecular geometry of the achiral molecules. The formation of the helical superstructures, namely hierarchical chirality, is attributed to the conformational chirality from the achiral banana-shaped liquid crystalline molecules, as evidenced by significant optical activity in time-resolved circular dichroism experiments. Selective area electron diffraction is performed to examine the structural packing of the hierarchical superstructures. As observed, the molecular disposition of the lamellar crystal is identical to that of the helical superstructure. Also, the diffraction patterns of the helical superstructures appeared arc-like patterns consisting of a series of reflections, suggesting that the helical morphology resulted from the curving of the lamellar crystals through a twisting and bending mechanism. Consequently, the model of molecular disposition in the self-assembled helical superstructures from the achiral banana-shaped molecules is proposed. The morphological evolution in this study may provide further understanding with respect to the chiral information transfer mechanism from specific molecular geometry to hierarchical chirality in the achiral banana-shaped molecules.
Highly efficient organic solar cells using a solution-processed active layer with a small molecule donor and pristine fullerene
(2014)
Lin, Hao-Wu
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Chang, Jung-Hao
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Huang, Wei-Ching
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Lin, Yu-Ting
;
Lin, Li-Yen
A new strategy has been successfully established to realize high efficiency small molecule organic solar cells with a solution-processed active layer composed of a small organic molecule as the donor and pristine C-70 as the acceptor. Using 1,2-dichlorobenzene as solvent, a homogeneous donor/C-70 blend active layer can be effectively formed either by spin- or bar-coating techniques. This method delivers organic solar cells with high power conversion efficiencies up to 5.9%.
Homochiral Evolution in Self-Assembled Chiral Polymers and Block Copolymers
(2017-04-01)
Wen, Tao
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Wang, Hsiao-Fang
;
Li, Ming-Chia
;
Ho, Rong-Ming
;
生物科技學系
The significance of chirality transfer is not only involved in biological systems, such as the origin of homochiral structures in life but also in man-made chemicals and materials. How the chiral bias transfers from molecular level (molecular chirality) to helical chain (conformational chirality) and then to helical superstructure or phase (hierarchical chirality) from self-assembly is vital for the chemical and biological processes in nature, such as communication, replication, and enzyme catalysis. In this Account, we summarize the methodologies for the examination of homochiral evolution at different length scales based on our recent studies with respect to the self-assembly of chiral polymers and chiral block copolymers (BCPs*). A helical (H*) phase to distinguish its P622 symmetry from that of normal hexagonally packed cylinder phase was discovered in the self-assembly of BCPs* due to the chirality effect on BCP self-assembly. Enantiomeric polylactide-containing BCPs*, polystyrene-b-poly(L-lactide) (PS PLLA) and polystyrene-b-poly(D-lactide) (PS-PDLA), were synthesized for the examination of homochiral evolution. The optical activity (molecular chirality) of constituted chiral repeating unit in the chiral polylactide is detected by electronic circular dichroism (ECD) whereas the conformational chirality of helical polylactide chain can be explicitly determined by vibrational circular dichroism (VCD). The H* phases of the self-assembled polylactide-containing BCPs* can be directly visualized by 3D transmission electron microscopy (3D TEM) technique at which the handedness (hierarchical chirality) of the helical nanostructure is thus determined. The results from the ECD, VCD, and 3D TEM for the investigated chirality at different length scales suggest the homochiral evolution in the self-assembly of the BCPs*. For chiral polylactides, twisted lamellae in crystalline banded spherulite can be formed by dense packing scheme and effective interactions upon helical chains from self-assembly. The handedness of the twisted lamella can be determined by using rotation experiment of polarized light microscopy (PLM). Similar to the self-assembly of BCPs*, the examined results suggest the homochiral evolution in the crystallized chiral polylactides. The results presented in this Account demonstrate the notable progress in the spectral and morphological determination for the examination of molecular, conformational, and hierarchical chirality in self-assembled twisted superstructures of chiral polymers and helical phases of block copolymers and suggest the attainability of homochiral evolution in the self-assembly of chiral homopolymers and BCPs*. The suggested methodologies for the understanding of the mechanisms of the chirality transfer at different length scales provide the approaches to give Supporting Information for disclosing the mysteries of the homochiral evolution from molecular level.
Induced Chain Alignment of Conjugated Polymers Within Nanoporous Template
(2011-07-22)
Lo, Kuan-Hsin
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Ho, Rong-Ming
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Liao, Yung-Ming
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Hsu, Chain-Shu
;
Massuyeau, Florian
This work presents a simple method to generate ordered conjugated polymer nanoarrays through a pore-filling process for nanoporous polymer templates so as to enhance the efficiency of photoluminescence (PL). PL results combined with the morphological evolution examined by scanning probe microscopy revealed that the enhanced PL reaches maximum intensity as the template pores are completely filled by conjugated polymers. Polarized PL spectroscopy and grazing incidence Fourier transform infrared spectroscopy were used to determine the chain orientation of templated conjugated polymer; the spectroscopic results indicate a parallel chain orientation along the cylindrical direction of nanopores. The induced alignment of the polymer chains is attributed to a nanoscale spatial effect that increases the PL intensity and the lifetime of the conjugated polymer. The enhanced luminescence of nanostructured conjugated polymers is highly promising for use in designing luminescent nanodevices.
Li-Ion Capacitor Integrated with Nano-network-Structured Ni/NiO/C Anode and Nitrogen-Doped Carbonized Metal-Organic Framework Cathode with High Power and Long Cyclability
(2019-08-28)
Cheng, Chung-Fu
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Chen, Yu-Ming
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Zou, Feng
;
Liu, Kewei
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Xia, Yanfeng
Lithium-ion capacitors (LICs) represent a new type of energy-storage devices, which have combined merits of high energy density Li-ion battery and high power density supercapacitor. Nevertheless, one significant challenge for LICs is the imbalanced kinetics between the fast capacitive cathode and relatively slow intercalation anode that limit the energy-storage performance. Here, the asymmetric LIC devices were developed based on a nitrogen-doped, carbonized zeolitic imidazolate framework (ZIF-8) cathode and a three-dimensional, nano-network-structured, conversion reaction-based Ni/NiO/C anode. These nanostructures associated with both the cathode and anode enable rapid electron and ions transport in the LIC devices, which allows the asymmetric LICs to be operated on either high energy mode (energy density of 114.7 Wh/kg at power density of 98.0 W/kg) or high power mode (power density of 60.1 kW/kg at energy density of 17.6 Wh/kg). The device also exhibited long-term cycle stability with 87% capacitance retention after 12 000 cycles. These results demonstrate that the rational design of nanoporous electrode structures can deliver a balanced, high-performance-activated cZIF-8 vertical bar Ni/NiO/C-based lithium-ion capacitor.
Luminescence Enhancement of Pyrene/Dispersant Nanoarrays Driven by the Nanoscale Spatial Effect on Mixing
(2013-02-05)
Lo, Kuan-Hsin
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Li, Ming-Chia
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Ho, Rong-Ming
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Zhao, Yuan-Chun
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Massuyeau, Florian
This work presents a simple method to generate ordered chromophore/dispersant nanoarrays through a pore-filling process for a nanoporous polymer template to enhance chromophore luminescence. Fluorescence results combining with the morphological evolution examined by scanning probe microscopy reveal that the enhanced luminescence intensity reaches the maximum intensity as the nanopores of the template are completely filled by the chromophore/dispersant mixture. The variation is attributed to nanoscale spatial effect on the enhanced mixing efficiency of chromophore and dispersant, that is, the alleviation of self-quenching problem, as evidenced by the results of attenuated total reflection Fourier transform IR spectroscopy combining with grazing incident wide-angle X-ray diffraction. The enhanced luminescence of the chromophore/dispersant nanoarrays driven by the nanoscale spatial effect is highly promising for use in designing luminescent nanodevices.
Twist Ferrocene Wires from Self-Assembly of Chiral Rod-Coil Organometallics
(2010)
Lin, Tz-Feng
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Ho, Rong-Ming
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Sung, Chien-Hung
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Ho, Ming-Shou
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Hsu, Chain-Shu
Variation of helical twisting power in self-assembled sugar-appended Schiff base chiral rod-coil amphiphiles
(2008-02-26)
Lin, Tz-Feng
;
Ho, Rong-Ming
;
Sung, Chien-Hung
;
Hsu, Chain-Shu
;
應用化學系
A series of sugar-appended Schiff base chiral rod-coil amphiphiles with various alkoxy chain lengths have been synthesized in order to elucidate the variation of the helical twisting power (HTP), that is, the inverse of the pitch length, of the helical texture in the self-assembly of the amphiphiles. The HTP induced by chiral sugar in the self-assembled helical morphology was dependent upon the alkoxy chain length. Increasing the alkoxy chain length caused the self-assembled morphology to change from platelet-like texture to helical-twist morphology with varying pitch length and then revert to the platelet-like texture. This result demonstrates that the HTP reaches a maximum as the alkoxy chain length changes. The transformation from platelet-like to helical-twist morphology is induced by significant steric hindrance, when the effective size of adjacent alkoxy chains reaches the threshold of helical twisting and bending, resulting in the formation of a chiral smectic C phase. However, as the alkoxy chain length increases further, the disordering of the alkoxy chain conformation in the smectic-like layered structure may give rise to a structural imperfection that reduces the steric-hindrance effect. Eventually, the steric-hindrance effect may reach a compromise with the structural imperfection to produce a platelet-like morphology, leading to the formation of a low-order smectic phase.