Browsing by Author "Lin, Hong-Cheu"

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A 0.05 V driven ammonia gas sensor based on an organic diode with a top porous layered electrode and an air-stable sensing film
(2019-06-07)
Madhaiyan, Govindasamy
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Chen, Chao-Hsuan
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Wu, Yi-Chu
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Horng, Sheng-Fu
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Zan, Hsiao-Wen
In this work, we successfully demonstrated an extremely-low-voltage (0.05 V) gas sensor based on a vertical organic diode with work-function-matched electrodes. With the designed electrodes (MoO3/Al vs. Al), the built-in field in the vertical diode is greatly reduced and hence the diode can be turned on at a very low voltage. By producing nanometer pores in the top electrode, the diode becomes a very sensitive gas sensor to detect ammonia in parts-per-billion (ppb) concentrations. Upon reducing the voltage from 5 V to 0.05 V, this sensor device shows an over 5-times enhancement in the sensitivity. The air-stable sensing film also exhibits a lifetime of 30 days in air. Finally, by connecting with an organic photovoltaic (OPV) device, the gas sensor can be directly powered and switched on by irradiating light on the OPV.
A cascade energy band structure enhances the carrier energy in organic vertical-type triodes
(2013-09-01)
Cheng, Shiau-Shin
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Ramesh, Mohan
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Chen, Guan-Yuan
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Fung, Chun-Lin
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Chen, Li-Ming
Organic vertical-type triodes (OVTs) based on the cascade energy band structure as emitter layer are studied. The electric characteristics were dramatically enhanced while incorporating the cascade energy under current driving and voltage driving modes. The improvement is attributed to that injection carriers can obtain higher energy through a stepwise energy level. When the device has a layered structure of F16CuPC (10 nm)/PTCDI (10 nm)/pentacene (100 nm) in emitter, it exhibits a common-base transport factor of 0.99 and a common-emitter current gain of 225 under current driving mode and exhibits a high current modulation-exceeding -520 mu A for a low collector voltage of -5 V and a base voltage of -5 V and the current on/off ratio of 10(3) under voltage driving mode. Furthermore, we realized first organic current mirror that exhibited out/in current ratio of 0.75 and output resistance of 10(5) Omega by using the OVTs. (C) 2013 Published by Elsevier B.V.
A cyanide-responsive supramolecular nanovalve based on Pd(II)-templated pseudo-rotaxane
(2015-01-01)
Raju, Mandapati V. Ramakrishnam
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Lin, Hong-Cheu
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材料科學與工程學系
;
Department of Materials Science and Engineering
We report here the design and synthesis of a nanovalve system consisting of a carrier based on mesoporous silica nanoparticles and mechanized with a square planar Pd(II)-templated pseudo-rotaxane. This nanovalve was responsive to demetalation by cyanide anions, followed by the concomitant release of both the macrocycles and the contents of the pores, in this instance dye indicators. Gate-keeping of the mesopores was achieved by the formation of an intact coordination between the monodentate pyridine axles soluble in aqueous solution and the tridentate macrocycle Pd complex via a square planar metal template approach. A facile nanovalve system responsive to an anionic stimulus was therefore developed. Luminescence spectrometry was successfully used to demonstrate that the anion-stimulated dye release from the nanovalves gated by the Pd(II) metal template was independent of pH.
A facile ratiometric fluorescent chemodosimeter for hydrazine based on Ing-Manske hydrazinolysis and its applications in living cells
(2014-04-01)
Raju, Mandapati V. Ramakrishnam
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Prakash, Epperla Chandra
;
Chang, Huan-Cheng
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Lin, Hong-Cheu
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材料科學與工程學系
A facile and sensitive fluorescent probe for hydrazine was successfully constructed, displaying excellent colorimetric and ratiometric responses towards hydrazine via Ing-Manske hydrazinolysis conditions in semi-aqueous buffer solution. Semi-empirical calculations as well as spectroscopic results revealed the signalling mechanism of the current probe under hydrazinolysis conditions, in which hydrazine exclusively deprotected the phthalimide group by an intermediate of phthalhydrazide. Extensive screening of pH effects on the probe with the aid of proton nuclear magnetic resonance and mass spectrometry supported the distinctive and diverse ratiometric responses under hydrazinolysis and basic hydrolysis conditions. Time resolved photoluminescence measurements of the probe further confirmed its discernible ratiometric responses probed at respective wavelengths. A distinctive ratiometric response under basic hydrolysis conditions and a successful utilization of probe towards hydrazine detection in living cells are demonstrated. (C) 2013 Elsevier Ltd. All rights reserved.
A fully-aqueous red-fluorescent probe for selective optical sensing of Hg2+ and its application in living cells
(2016-07)
Pola, Murali Krishna
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Raju, Mandapati V. Ramakrishnam
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Lin, Chein-Ming
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Putikam, Raghunath
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Lin, Ming-Chang
A new red-fluorescent mercury ion sensor material is designed and synthesized, which is composed of at weezer-shaped hydrophilic probe containing bifurcated soft-base atoms N and S coupled with 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) unit. By virtue of the strong electron-accepting nature of TCF unit (as a push pull chromophore), this designed sensor material can selectively detect Hg2+ over various tested metal ions in a 100% aqueous medium via naked-eye and photoluminescence (PL) observations. Theoretical and time-resolved photoluminescence measurements further confirmed the selectivity and reversibility of the probe towards Hg2+ via intramolocular charge transfer mechanism in this sensor material. Moreover, the living cell tests by confocal fluorescence images of this sensor material towards Hg2+ were also investigated. Finally, distinguished absorption changes and fluorescence quenching spectral appearances allowed us to present the selective optical indicator of Hg2+ via TCF moiety for the first time. (C) 2016 Elsevier Ltd. All rights reserved.
A new pyrene-based aggregation induced ratiometric emission probe for selective detections of trivalent metal ions and its living cell application
(2015-02-01)
Singh, Ashutosh
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Singh, Ravinder
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Shellaiah, Muthaiah
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Prakash, Epperla Chandra
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Chang, Huan-Cheng
We synthesize a newly designed pyrene-based fluorescent probe FBP containing a Schiff base and amide linkage as a receptor, which demonstrates selective UV-vis and fluorometric detections of trivalent metal ions in various semi-aqueous solution conditions. Interestingly, by increasing water contents the aggregation induced ratiometric emissions (AIREs) of photoluminescence in FBP solutions (in DMSO/H2O) are enhanced from blue to green due to the excimer formation of the aggregates in water. In addition, the enhanced aggregated ratiometric green fluorescence behaviors of FBP in the presence of trivalent metal ions (Al3+, Fe3+, and Cr3+) are observed in semi-aqueous solutions as well as the solid state, which is well utilized to detect trivalent metal ions in living cells. Further verification of the probe detections, their interactions toward trivalent metal ions are well characterized by the time-resolved photoluminescence (TRPL) of spectroscopic responses as well as theoretical calculations. Therefore, we believe the application of such a new AIRE-based approach is first reported among Schiff base and pyrene-based fluorescentchemo- and bio-sensors. (C) 2014 Elsevier B.V. All rights reserved.
A novel ball milling technique for room temperature processing of TiO2 nanoparticles employed as the electron transport layer in perovskite solar cells and modules
(2018-04-28)
Singh, Mriganka
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Chiang, Chien-Hung
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Boopathi, Karunakara Moorthy
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Hanmandlu, Chintam
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Li, Gang
Anatase titanium dioxide (an-TiO2) is often used as the electron transporting material (ETM) in planar-heterojunction perovskite solar cells (PSCs) because of its excellent semiconductor characteristics, outstanding optical transmittance, and suitable band structure. Herein, we report an inexpensive method for mass-scale production of TiO2 ETMs at room temperature (RT similar to 30 degrees C), involving the grinding of large clumps of an-TiO2 to form a suspension of TiO2 nanoparticles (NPs) in isopropyl alcohol for meso-superstructured PSCs. This process does not involve any chemical synthesis; it is a purely physical process. The lowest unoccupied molecular orbital (LUMO) of ground an-TiO2 NPs, estimated using ultraviolet photoelectron spectroscopy (UPS), was ca. 4.06 eV, which is a salient feature for the active layer. A regular perovskite solar cell (PSC) based on a CH3NH3PbI3 absorber and ground an-TiO2 ETL exhibited a champion power conversion efficiency (PCE) of 17.43% with an active area of 0.1 cm(2). The same ground an-TiO2 NPs were used to fabricate a large-area (designated area: 25.2 cm(2)) PSC and a PCE of 14.19% was achieved. PSC devices incorporating the ground an-TiO2 NP ETLs exhibited an attractive long-term device stability, with the PCE retaining approximately 85% of the initial values after 80 days.
A Novel Diketopyrrolopyrrole (DPP)-Based [2]Rotaxane for Highly Selective Optical Sensing of Fluoride
(2013-03-15)
Raju, Mandapati V. Ramakrishnam
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Lin, Hong-Cheu
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材料科學與工程學系
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Department of Materials Science and Engineering
A novel [2]rotaxane based on an orthogonal H-bonded motif and 3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DPP) with controlled topicity was successfully constructed, displaying excellent stimulated responses toward anion and solvent polarity. The preorganized host selectively recognized F- with high optical sensitivity and reversibility via enhanced positive cooperativity and noncovalent interaction by evidence of a shorter fluorescence lifetime.
A plug-and-measure diagnostic tool for flux, resolution and beam size of a soft X-ray beamline
(2015-09-01)
Wei, Ching-Hsuan
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Lin, Hong-Cheu
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Lin, Shang-Wei
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Yuh, Jih-Young
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材料科學與工程學系
A compact multi-functional diagnostic tool has been installed for commissioning beamlines at the Taiwan Light Source. For a photon beam, the instrument can measure the photon flux, energy resolution and beam size, consecutively with a photodiode or gold mesh, a windowless gas cell and a movable fluorescence screen viewport. Two gratings with ruling densities of 350 and 1000 lines mm(-1) and dispersing photons of energies from 80 to 1200 eV were calibrated with a photon flux of 10(11) photon s(-1) at slit openings of 50 mu m x 50 mu m; a maximum resolving power of greater than 10000 was certified with an absorption spectra of gaseous samples. Pressure differences over four orders of magnitude were achieved between the ion chamber and the flux measurement chamber with a single capillary differential pumping stage. A sequence of beam profiles was measured by moving continuously in the vicinity of the nominal focal positions. This tool is useful in commissioning or trouble-shooting at most beamlines in a synchrotron facility.
A theranostic nrGO@MSN-ION nanocarrier developed to enhance the combination effect of sonodynamic therapy and ultrasound hyperthermia for treating tumor
(2016)
Chen, Yu-Wei
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Liu, Tse-Ying
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Chang, Po-Hsueh
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Hsu, Po-Hung
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Liu, Hao-Li
Sonodynamic therapy (SDT), which induces activation of sonosensitizers in cancer cells through ultrasound irradiation, has emerged as an alternative and promising noninvasive therapeutic approach to kill both superficial and deep parts of tumors. In this study, mesoporous silica (MSN) grown on reduced graphene oxide nanosheet (nrGO) capped with Rose Bengal (RB)-PEG-conjugated iron-oxide nanoparticles (IONs), nrGO@MSN-ION-PEG-RB, was strategically designed to have targeted functionality and therapeutic efficacy under magnetic guiding and focused ultrasound (FUS) irradiation, respectively. The singlet oxygen produced by ultrasound-activated RB and the ultrasound-induced heating effect was enhanced by rGO and IONs, which improved the cytotoxic effect in cancer cells. In an animal experiment, we demonstrated that the combination of sonodynamic/hyperthermia therapy with magnetic guidance using this nanocomposite therapeutic agent can produce remarkable efficacious therapy in tumor growth inhibition. Furthermore, the combination effect induced by FUS irradiation produces significant damage to both superficial and deep parts of the targeted tumor.
Acid/Base and H2PO4- Controllable High-Contrast Optical Molecular Switches with a Novel BODIPY Functionalized [2]Rotaxane
(2015-12-09)
Arumugaperumal, Reguram
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Srinivasadesikan, Venkatesan
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Raju, Mandapati V. Ramakrishnam
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Lin, Ming-Chang
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Shukla, Tarun
A novel multifunctional mechanically interlocked switchable [2]rotaxane R4 containing two molecular stations and rotaxane arms terminated with boron-dipyrromethene (BODIPY) fluorophores and its derivatives were synthesized for the first time by CuAAC click reaction. The shuttling motion of macrocyde between the dibenzylammonium and triazolium recognition sites and the distance dependent photoinduced electron transfer process of R4 is demonstrated by utilizing external chemical stimuli (acid/base). Interestingly, the reversible self-assembly process of R4 was recognized by the acid-base molecular switch strategy. Notably, two symmetrical triazolium groups acted as molecular stations, H2PO4- receptors, and H-bonded donors. Both [2]rotaxane R4 and thread R2 demonstrated excellent optical responses and high selectivity toward H2PO4- ion. The specific motion and guest-host interactions of mechanically interlocked machines (MIMs) were also further explored by quantum mechanical calculations. The thread R2 also demonstrated to enable the detection of H2PO4- in RAW 264.7 cells successfully.
Alkyl chain self ordering, induction and suppression of mesophase by Cu(II) containing [1,2,3]-triazole-based bidentate salicylaldimine ligands: synthesis, characterisation and X-ray diffraction studies
(2014-12-02)
Heng, Boon-Teck
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Yeap, Guan-Yeow
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Mahmood, Wan Ahmad Kamil
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Han, Chun-Chieh
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Lin, Hong-Cheu
Some new Cu(II) complexes containing [1,2,3]-triazole-based bidentate salicylaldimine and its analogues with terminal substituent (F, Cl, Br and I) have been synthesieed. All the target complexes and their uncoordinated ligands were elucidated by elemental analysis and spectroscopic techniques (UV-visible, FT-IR, 1D, 2D H-1 and C-13-NMR). The polarising optical microscope and differential scanning calorimetry (DSC) have disclosed all complexes and ligands are mesomorphic except the complex without any terminal substituent. The fluoro-substituted complexes with even parity C14H29 and C16H33 exhibit new enantiotropic nematic phase which was absent in their corresponding ligands, whereas the suppression of SmC phase occurred for all complexes with longer C16H33 and C18H37. X-ray diffraction confirmed the existence of SmA, SmC and N phases for complexes and ligands. The other notable feature is that the self-ordering of terminal alkyl chain occurred in SmA and SmC phases of complexes with even terminal alkyl chain ranging from C14H29 to C18H33. Their corresponding ligands exhibit intercalated structure of SmA and SmC phases. The thermal behaviour studies show that the fluoro-substituted triazole-based complexes possess lowest phase transition temperature and more stable as compared to other substituent which decomposed during the isotropisation.
An Acid-Base Controllable Hierarchical Nanostructure from a NIR-Absorbing Conjugated Polyrotaxane-Based Optical Molecular Switch
(2013-09-10)
Raju, Mandapati V. Ramakrishnam
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Raghunath, P.
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Lin, Ming-Chang
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Lin, Hong-Cheu
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材料科學與工程學系
To investigate the supramolecular interactions of the mechanically interlocked rotaxane pendants and conjugated polymer backbones, four analogous polymers were systematically synthesized by copolymerization of a 9-alkylidene-9H-fluorene monomer with various monomers, which contained a diketopyrrolopyrrole unit tethered with a dumbbell unit, a metalated [2]rotaxane, a demetalated orthogonal H-bonded [2]rotaxane, and a simple alkyl chain, to furnish P1, P2, P3, and P4, respectively. Prevailing H-1 NMR and UV-vis to NIR titration profiles indicated that the novel polyrotaxane P3 showed a sensitive and reversible acid base molecular switch capability via supramolecular interactions in contrast to the other polymers (P1, P2, and P4). Compared with the other polymers, P3 possessed a narrower bandgap, which was also confirmed by the computational study. Prominently, the monitoring of a controllable nanoself-assembly process of P3 was obtained by reversible acid base molecular switch approaches. The orthogonal H-bonded pendant [2]rotaxane unit and the steric demand of P3 judiciously allowed to morph into a hierarchical nanostructure via interconvertible H-bonds, anion-pi and pi-pi stackings, and hydrophobic interactions.
An Unprecedentedly Huge Square-Grid Copper(II)-Organic Framework Material Built from a Bulky Pyrene-Derived Elongated Cross-Shaped Scaffold
(2009-09-21)
Tsai, Chen-Chuan
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Luo, Tzuoo-Tsair
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Yin, Jen-Fu
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Lin, Hong-Cheu
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Lu, Kuang-Lieh
A new bulky pyrene-derived elongated cross-shaped organic scaffold was successfully incorporated into a highly porous, non-interpenetrated square-grid copper(II)-organic framework material with the unprecedentedly huge dimensions of 25.5 x 25.5 angstrom(2), while the layer-to-layer NH center dot center dot center dot N interaction leads to a unique hydrogen-bonded 6(4).8(2)-nbo net.
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
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Yang, Chang-Chung
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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
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Long, Chun-Ji
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Lin, Hsin-Chieh
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Chuang, Wei-Tsung
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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
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Li, Wan-Sheung
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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.
Correlation between Exciton Lifetime Distribution and Morphology of Bulk Heterojunction Films after Solvent Annealing
(2010-05-20)
Huang, Jen-Hsien
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Li, Kuang-Chieh
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Chien, Fan-Ching
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Hsiao, Yu-Sheng
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Kekuda, Dhananjay
We have synthesized a low-bandgap polymer, bithiazole-based polymer (PCPDTTBT) containing cyclopentadithiophene and thiophene units, and studied its opticophysical properties and morphologies in bulk heterojunction films after annealing. We used confocal optical microscopy in conjunction with a fluorescence module to record exciton lifetime images within photoactive layers of PCPDTTBT and [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM). These images, which were consistent with those recorded using atomic force microscopy and transmission electron microscopy, revealed that phase separation of PCPDTTBT and PCBM occurred during slow solvent evaporation. This phase separation not only provided bicontinuous pathways for carrier transport to the respective electrodes hut also enhanced the degree of polymer chain stacking, thereby improving the absorption and balancing the electron and hole mobilities. We tested the performance of solar cells incorporating PCPDTTBT and various fullerene derivatives. Under AM 1.5 G illumination (100 mW cm(-2)), a PCPDTTBT/bisPCBM-based solar cell exhibited a power conversion efficiency of 3.8%, with a short circuit current of 7.3 mA cm(-2), an open circuit voltage of 0.88 V, and a fill factor of 59.1%.
Design, synthesis, photophysical, and electrochemical properties of DCM-based conjugated polymers for light-emitting devices
(2012-09-15)
Vanjinathan, Mahalingam
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Lin, Hong-Cheu
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Nasar, A. Sultan
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材料科學與工程學系
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Department of Materials Science and Engineering
A series of conjugated hyperbranched polymers, hyperbranched copolymers, and linear polymers containing 2-pyran-4-ylidenemalononitrile (acceptor) and triphenylamine/fluorene (donor) units were synthesized and characterized by FTIR, 1H NMR, thermogravimetric analyses, differential scanning calorimetry, gel permeation chromatography, UVvisible, photoluminescence, and cyclic voltammetry measurements. All the polymers show red-light emission in the range of 566656 nm both in solution and in solid state. The quantum efficiency of the polymers was in the range of 5682%. Among the six polymers synthesized, only polymers containing fluorene units show Tg and polymers based on triphenylamine not exhibit Tg. The band gap of these polymers were found to be reasonably low; hyperbranched copolymer containing fluorene unit shows lowest band gap of 2.18 eV due to the stabilization of LUMO energy level by the electron withdrawing ?CN groups. The thermal and solubility behavior of the polymers were found to be good. All the EL spectra of the devices (indium-tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polymer/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline/tris(8-hydroxyquinoline)aluminum)/LiF/Al) show red-light emission, and the device fabricated with P3 and P4 shows maximum luminance and luminous efficiency of 4104 cd m-2 and 0.55 cd angstrom-1 and 3696 cd m-2 and 0.47 cd angstrom-1, respectively, indicates that they had the best carrier balance. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
"Design, synthesis, photophysical, and electrochemical properties of DCM-based conjugated polymers for light-emitting devices"
(1970-01-01)
Vanjinathan, Mahalingam
;
Lin, Hong-Cheu
;
Nasar, A. Sultan
;
材料科學與工程學系
;
Department of Materials Science and Engineering
"A series of conjugated hyperbranched polymers, hyperbranched copolymers, and linear polymers containing 2-pyran-4-ylidenemalononitrile (acceptor) and triphenylamine/fluorene (donor) units were synthesized and characterized by FTIR, 1H NMR, thermogravimetric analyses, differential scanning calorimetry, gel permeation chromatography, UVvisible, photoluminescence, and cyclic voltammetry measurements. All the polymers show red-light emission in the range of 566656 nm both in solution and in solid state. The quantum efficiency of the polymers was in the range of 5682%. Among the six polymers synthesized, only polymers containing fluorene units show Tg and polymers based on triphenylamine not exhibit Tg. The band gap of these polymers were found to be reasonably low; hyperbranched copolymer containing fluorene unit shows lowest band gap of 2.18 eV due to the stabilization of LUMO energy level by the electron withdrawing ?CN groups. The thermal and solubility behavior of the polymers were found to be good. All the EL spectra of the devices (indium-tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polymer/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline/tris(8-hydroxyquinoline)aluminum)/LiF/Al) show red-light emission, and the device fabricated with P3 and P4 shows maximum luminance and luminous efficiency of 4104 cd m-2 and 0.55 cd angstrom-1 and 3696 cd m-2 and 0.47 cd angstrom-1, respectively, indicates that they had the best carrier balance. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012"