Browsing by Author "Chiang, I-Hung"

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Applications of novel dithienothiophene- and 2,7-carbazole-based conjugated polymers with surface-modified ZnO nanoparticles for organic photovoltaic cells
(2011-05-31)
Fang, Hsiao-Ping
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Chiang, I-Hung
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Chu, Chih-Wei
;
Yang, Chang-Chung
;
Lin, Hong-Cheu
Two kinds of novel conjugated polymers containing 2,7-carbazole, thiophene, and fused-dithienothiophene rings as backbones bearing acid-protected and benzoic acid pendants (PC1 and PC2, respectively) were utilized for organic solar cell applications. The absorption spectra of these polymers (in both solutions and solid films) showed an absorption range at 300-580 nm. Furthermore, ZnO nanoparticles were synthesized and surface-modified with pyridyl surfactants (ZnOpy) to be ca. 3-4 nm. The pyridyl surfactants of ZnOpy nanoparticles (as electron acceptors to partially replace expensive electron acceptor PCBM) not only induce supramolecular interactions with benzoic acid pendants of polymer PC2 via H-bonds, but also enhance the homogeneous dispersions of ZnOpy nanoparticles in polymer PC2. Thus, the ternary systems of PC1-N2/ZnOpy/PCBM in weight ratios of 1:0.05:1 and 1:0.1:1 were investigated in bulk heterojunction polymer solar cells (PSCs). Under the standard illumination of AM 1.5, 100 mW/cm(2), the best power conversion efficiency (PCE) of the PSC cell containing a polymer blend of PC2/ZnOpy/PCBM = 1:0.05:1 reached PCE = 0.55%, with J(sc) = 2.11 mA/cm(2), V(oc) = 0.88 V, and FF = 29.4%. (C) 2011 Elsevier B.V. All rights reserved.
Broad Ranges and Fast Responses of Single-Component Blue-Phase Liquid Crystals Containing Banana-Shaped 1,3,4-Oxadiazole Cores
(2014-01-08)
Chiang, I-Hung
;
Long, Chun-Ji
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Lin, Hsin-Chieh
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Chuang, Wei-Tsung
;
Lee, Jey-Jau
In this study, we synthesized two novel 1,3,4-oxadiazole-based bent-core liquid crystals (OXD7*, OXD5B7F*) containing a chiral tail that display broad ranges of the blue phase III (34 and 7 K, respectively); we characterized them using polarized optical microscopy, differential scanning calorimetry, and circular dichroism. The electro-optical responses of both of these liquid crystals are much faster than those of previously reported single-component blue-phase liquid crystals. To optimize its electro-optical performance, we mixed OXD7* (the blue-phase range of which is broader than that of OXD5B7F*) with its analogue OXD6 (at weight ratios of 6:4 and 4:6). We also performed molecular modeling of single-component BPLCs (OXD7* and OXD5B7F*) to analyze the possible parameters affecting their blue phase ranges.
Configuration Effects of H-Bonded Sites and Rigid Core Lengths on H-Bonded Banana-Shaped Liquid Crystalline Supramolecules Consisting of Symmetric Trimers and Asymmetric Heterodimers
(2009-11-05)
Wang, Ling-Yung
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Chiang, I-Hung
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Yang, Po-Jen
;
Li, Wan-Sheung
;
Chao, I-To
Several series of novel banana-shaped H-bonded symmetric trimers (with two H-bonds) and asymmetric heterodimers (with one H-bond) were self-assembled by appropriate molar ratios of proton donors (H-donors) and acceptors (H-acceptors). The influences of H-bonded linking positions and aromatic ring numbers (4-8 aromatic rings in the rigid cores) as well as the chain lengths (n, m = 12 or 16, respectively, in the flexible parts) on the mesomorphism and the switching behavior of the bent-core supramolecules were evaluated and theoretically analyzed. Except for the supramolecular structures with longer rigid cores or shorter flexible chains possessing the rectangular columnar (Col(r) or Bl) phase, the SmC(A)P(A) phase was revealed in most supramolecular asymmetric heterodimers and switched to the SmC(S)P(F) phase by applying electric fields. The polar smectic C phase was dominated for those with H-bonded sites apart from the core center. Interestingly, the SmA and nematic phases were observed in H-bonded asymmetric dimers with H-bonded sites close to the core center, which theoretically proved that the polar smectic C phase was disfavored due to an unfavorable bend angle (smaller than the lower limit of 110 degrees) in the lowest-energy H-bonded conformer. Compared with the fully covalently bonded analogue, lower transition temperatures and lower threshold voltages were developed in the H-bonded asymmetric dimers with the polar smectic C phase. On the basis of the theoretical calculations of molecular modeling, the existence of polar switching behavior in the polar smectic C phase of asymmetric heterodimers; was proven to be associated with their configurations with higher dipole moments and suitable bend angles. Furthermore, the lack of polar switching behavior in supramolecular symmetric trimers, which exhibited the regular SmC phase with weak electrical stabilities, was related to their configurations with smaller dipole moments and confirmed by theoretical calculations.
Shape and confinement effects of various terminal siloxane groups and C60 on supramolecular interactions of hydrogen-bonded bent-core liquid crystals
(2015-01-01)
Lin, Hong-Cheu
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Chiang, I-Hung
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Chuang, Wei-Tsung
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Lu, Chia-Lin
;
Liao, Chun-Yen
Shape and Confinement Effects of Various Terminal Siloxane Groups on Supramolecular Interactions of Hydrogen-Bonded Bent-Core Liquid Crystals
(2015-07-14)
Chiang, I-Hung
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Chuang, Wei-Tsung
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Lu, Chia-Lin
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Lee, Ming-Tao
;
Lin, Hong-Cheu
To investigate the shape and confinement effects of the terminal siloxane groups on the self-assembled behavior of molecular arrangements in hydrogen-bonded (H-bonded) bent-core complexes, four H-bonded bent-core complexes Si, P1, C4, and P8 with string-, ring-, and cagelike siloxane termini (i.e., linear siloxane unit -Si-O-Si-O-Si, cyclic siloxane unit (Si-O)(4), and silsesquioxane unit PUSS, respectively) were synthesized and investigated. By X-ray diffraction measurements, different types of SmCG (B8) phases and leaning angles were controlled by the shape effect of the string- and cage-like siloxane termini for Si and P1 (with only one arm of H-bonded bent-core), respectively. In addition, the confinement effect of Pi, C4, and P8 (accompanied by increasing the numbers of attached H-bonded bent-core arms) resulted in higher transition temperatures and the diminishing of mesophasic ranges (even the disappearance of mesophase in P8). Moreover, AFM images showed the bilayer smectic CG phases of Si and P1 were aligned to reveal highly ordered thread-like structures by a DC field. By spontaneous polarization measurements within the mesophasic ranges, Si and P1 showed ferroelectric transitions but C4 displayed antiferroelectricity. Finally, the electro-optical performance of B8 phases could be optimized through binary mixtures of Si and P1, and a well aligned modulated ribbon phase could be formed via specific molar ratios of the binary mixtures.
Supramolecular Assembly of H-Bonded Side-Chain Polymers Containing Conjugated Pyridyl H-Acceptor Pendants and Various Low-Band-Gap H-Donor Dyes Bearing Cyanoacrylic Acid Groups for Organic Solar Cell Applications
(2009-11-15)
Liang, Tzung-Chi
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Chiang, I-Hung
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Yang, Po-Jen
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Kekuda, Dhananjay
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Chu, Chih-Wei
Novel supramolecular side-chain polymers were constructed by complexation of proton acceptor (H-acceptor) polymers, i.e., side-chain conjugated polymers P1-P2 containing pyridyl pendants, with low-band-gap proton donor (H-donor) dyes S1-S4 (bearing terminal cyanoacrylic acids) in a proper molar ratio. Besides unique mesomorphic properties confirmed by DSC and XPD results, the H-bonds of supramolecular side-chain structures formed by pyridyl H-acceptors and cyanoacrylic acid H-donors were also confirmed by FTIR measurements. H-donor dyes S1-S4 in solid films exhibited broad absorption peaks located in the range of 471-490 nm with optical band-gaps of 1.99-2.14 eV. Furthermore, H-bonded polymer complexes P1/S1-P1/S4 and P2/S1-P2/S4 exhibited broad absorption peaks in the range of 440-462 nm with optical band-gaps of 2.11-2.25 eV. Under 100 mW/cm(2) of AM 1.5 white-light illumination, the bulk heterojunction polymer solar cell (PSC) devices containing an active layer of H-bonded polymer complexes P1/S1-P1/S4 and P2/S1-P2/S4 (as electron donors) mixed with [6,6]-phenyl C(61) butyric acid methyl ester (i.e., PCBM, as an electron acceptor) in the weight ratio of 1:1 were investigated. The PSC device containing H-bonded polymer complex P1/S3 mixed with PCBM (1:1 w/w) gave the best preliminary result with an overall power conversion efficiency (PCE) of 0.50%, a short-circuit current of 3.17 mA/cm(2), an open-circuit voltage of 0.47 V, and a fill factor of 34%. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5998-6013, 2009
Synthesis and application of H-Bonded cross-linking polymers containing a conjugated pyridyl H-Acceptor side-chain polymer and various carbazole-based H-Donor dyes bearing symmetrical cyanoacrylic acids for organic solar cells
(2010-12-10)
Sahu, Duryodhan
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Padhy, Harihara
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Patra, Dhananjaya
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Kekuda, Dhananjay
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Chu, Chih-Wei
A series of novel hydrogen-bonded (H-bonded) cross-linking polymers were generated by complexing various proton-donor (H-donor) solar cell dyes containing 3,6- and 2,7-functionalized electron-donating carbazole cores bearing symmetrical thiophene linkers and cyanoacrylic acid termini with a proton-acceptor (H-acceptor) side-chain homopolymer carrying pyridyl pendants (with 1/2 M ratio of H-donor/H-acceptor). The supramolecular H-bonded structures between H-donor dyes and the H-acceptor side-chain polymer were confirmed by FTIR measurements. The effects of the supramolecular architecture on optical, electrochemical, and organic photovoltaic (OPV) properties were investigated. From DFT (density functional theory) calculations, the optimized geometries of organic dyes reflected that the carbazole cores of H-donor dyes were coplanar with the conjugated thiophenes and cyanoacrylic acids, which is essential for strong conjugations across the donor-acceptor units in D1-D4 dyes. Under 100 mW/cm(2) of AM 1.5 white-light illumination, bulk heterojunction (BHJ) OPV cell devices containing an active layer of H-bonded polymers (PDETP/D1-D4) as an electron donor blended with [6,6]-phenyl C(61)-butyric acid methyl ester (PCBM) as an electron acceptor in a weight ratio of 1:1 were explored. From the preliminary investigations, the OPV device containing 1:1 weight ratio of H-bonded polymer PDFTP/D2 and PCBM showed the best power conversion efficiency (PCE) value of 0.31% with a short-circuit current (J(sc)) of 1.9 mA/cm(2), an open-circuit voltage (V(oc)) of 0.55 V. and a fill factor (FF) of 29%, which has a higher PCE value than the corresponding H-donor D2 dye (PCE = 0.15%) or H-acceptor PDFTP homopolymer (PCE = 0.02%) blended with PCBM in 1:1 weight ratio. (C) 2010 Elsevier Ltd. All rights reserved.
Synthesis and applications of main-chain Ru(II) metallo-polymers containing bis-terpyridyl ligands with various benzodiazole cores for solar cells
(2011)
Padhy, Harihara
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Sahu, Duryodhan
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Chiang, I-Hung
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Patra, Dhananjaya
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Kekuda, Dhananjay
A series of p-conjugated bis-terpyridyl ligands (M1-M3) bearing various benzodiazole cores and their corresponding main-chain Ru(II) metallo-polymers were designed and synthesized. The formation of metallo-polymers were confirmed by NMR, relative viscosity, and UV-visible titration measurements. The effects of electron donor and acceptor interactions on their thermal, optical, electrochemical, and photovoltaic properties were investigated. Due to the strong intramolecular charge transfer (ICT) interaction and metal to ligand charge transfer (MLCT) in Ru(II)-containing polymers, the absorption spectra covered a broad range of 260-750 nm with the optical band gaps of 1.77-1.63 eV. In addition, due to the broad sensitization areas of the metallo-polymers, their bulk heterojunction (BHJ) solar cell devices containing [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) as an electron acceptor exhibited a high short-circuit current (J(sc)). An optimum PVC device based on the blended polymer P1 : PCBM = 1 : 1 (w/w) achieved the maximum power conversion efficiency (PCE) value up to 0.45%, with V(oc) = 0.61 V, J(sc) = 2.18 mA cm(-2), and FF = 34.1% (under AM 1.5 G 100 mW cm(-2)), which demonstrated a novel family of conjugated polyelectrolytes with the highest PCE value comparable with BHJ solar cells fabricated from ionic polythiophene and C(60).
Synthesis of novel dithienothiophene- and 2,7-carbazole-based conjugated polymers and H-bonded effects on electrochromic and photovoltaic properties
(2012-12-15)
Fang, Hsiao-Ping
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Lin, Jia-Wei
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Chiang, I-Hung
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Chu, Chih-Wei
;
Wei, Kung-Hwa
Three kinds of dithienothiophene/carbazole-based conjugated polymers (P1P3), which bear acid-protected and benzoic acid pendants in P2 and P3, respectively, were synthesized via Suzuki coupling reaction. Interestingly, P1P3 exhibited reversible electrochromism during the oxidation processes of cyclic voltammogram studies, and P3 (with H-bonds) revealed the best electrochromic property with the most noticeable color change. According to powder X-ray diffraction (XRD) analysis, these polymers exhibited obvious diffraction features indicating bilayered packings between polymer backbones and p-p stacking between layers in the solid state. Compared with the XRD data of P2 (without H-bands), H-bonds of P3 induced a higher crystallinity in the small-angle region (corresponding to a higher ordered bilayered packings between polymer backbones), but with a similar crystallinity in the wide angle region indicating a comparable p-p stacking distance between layers. Moreover, based on the preliminary photovoltaic properties of PSC devices (P1P3 blended individually with PCBM acceptor in the weight ratio of 1:1), P3 (with H-bonds) possessed the highest power conversion efficiency of 0.61% (with Jsc = 2.26 mA/cm2, FF = 29.8%, and Voc = 0.9 V). In contrast to P2 (without H-bands), the thermal stability, crystallinity, and electrochromic along with photovoltaic properties of P3 were generally enhanced due to its H-bonded effects. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
The first blue phase reactive monomers containing a bi-mesogenic core and their side-chain polymers
(2015-01-01)
Wei, Chong-Lun
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Lin, Yen-Ting
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Chang, Jin-Huai
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Chiang, I-Hung
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Lin, Hong-Cheu
Two novel blue phase (BP) reactive monomers M1 and M2 containing a bi-mesogenic core are first reported by introducing two end-attached acrylic spacers with different lengths. Due to the self-assembly of bi-mesogenic cores with the same side-by-side end-attached acrylate spacers in homopolymers P1 and P2, no blue phase could be induced by homopolymerization of M1 and M2. However, by interrupting the self-assembly of bi-mesogenic cores with different side-by-side spacer lengths of copolymers P12, double-twisted cylinders of BPIII could be further extended by copolymerization of M1 and M2 with different molar ratios. With M1: M2 = 5 : 5 (molar ratio) in both side-chain copolymers P12(soln: 5/ 5) and P12(photo: 5/5) rather than binary mixture M1/M2(5/5), the widest BPIII ranges of 5.3 degrees C and 3.8 degrees C could be obtained by solution-and photo-polymerization, respectively.