Browsing by Author "Chu, Yu-Lin"

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A cross-linkable triphenylamine derivative as a hole injection/transporting material in organic light-emitting diodes
(2015-01-01)
Shih, Hsi-Kang
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Chu, Yu-Lin
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Chang, Feng-Chih
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Zhu, Chao-Yuan
;
Kuo, Shiao-Wei
We have synthesized TPABZ, a new thermally cross-linkable triphenylamine derivative containing a benzoxazine functional group, for application in organic light-emitting diodes (OLEDs). We used differential scanning calorimetry, thermogravimetric analysis, UV-Vis spectroscopy, and cyclic voltammetry to investigate the thermal, physical, and electrochemical properties of TPABZ, which is readily polymerized, through ring-opening polymerization of its benzoxazine unit, upon heating at 220 degrees C for 30 min. The cured TPABZ (P-TPABZ) is suitable for use as a hole injection/transport material in OLEDs because it has an appropriate HOMO energy level (-5.16 eV) to form a stepwise energy ladder and a high LUMO energy level (-1.68 eV) with great potential for electron blocking. We fabricated multilayered OLEDs (ITO/TPABZ or P-TPABZ/NPB/Alq(3)/LiF/Al) through successive spin-coating and vacuum deposition processes; the device incorporating P-TPABZ exhibited good performance (EQE: 2.44%; LEmax: 8.42 cd A(-1); PEmax: 4.34 lm W-1).
A new benzoxazine containing uracil, complementary functionality
(2011)
Yen, Ying-Chieh
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Cheng, Chih-Chia
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Chu, Yu-Lin
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Chang, Feng-Chih
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應用化學系
A new benzoxazine, uracil containing benzoxazine (UBz), has been successfully synthesized. The FTIR and DSC measurement of the poly(UBz)/poly(BA-a) blends indicated that hydrogen bonding interactions between uracil groups would result in a decrease in the exothermic peak temperature. In addition, the PL measurement confirmed that the poly(UBz)/poly(BA-a) blend possessed complementary behavior.
A New Supramolecular Hole Injection/Transport Material on Conducting Polymer for Application in Light-Emitting Diodes
(2012-04-10)
Chu, Yu-Lin
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Cheng, Chih-Chia
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Yen, Ying-Chieh
;
Chang, Feng-Chih
;
應用化學系
A new supramolecular POSS electroluminescent material
(2012)
Chu, Yu-Lin
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Cheng, Chih-Chia
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Chen, Ya-Ping
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Yen, Ying-Chieh
;
Chang, Feng-Chih
A new polyhedral oligomeric silsesquioxane (POSS) core star-like supramolecular blue-light electroluminescent material, 4-uracilbutyl-1-methylpyrene ether (U-PY)/octakis[dimethyl(N-(6-acetamidopyridin- 2 yl))siloxy] silsesquioxane (ODAP-POSS) has been synthesized. This U-PY/ODAP-POSS contains eight pyrene chromophore arms formed through complementary uracil-diamidopyridine (U-DAP) pairs and exhibits high quantum efficiencies and good solution processing properties. The photoluminescence spectra of U-PY/ODAP-POSS (50/50) reveal that the color is stable after heating the sample at 150 degrees C for 1 h, in contrast, the pyrene/ODAP-POSS (50/50) shows significant thermal quenching. An electroluminescence (EL) device based on U-PY/ODAP-POSS exhibits higher maximum brightness and higher luminance efficiency relative to that of the U-PY. In addition, U-PY/ODAP-POSS also behaves as an effective dopant that enhances energy transfer from itself to MEH-PPV. The U-PY/ODAP-POSS-doped MEH-PPV blends exhibit high luminance efficiency, 1.45 times greater than MEH-PPV.
A solvent-resistant azide-based hole injection/transporting conjugated polymer for fluorescent and phosphorescent light-emitting diodes
(2015-01-01)
Huang, Cheng-Wei
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Chang, Feng-Chih
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Chu, Yu-Lin
;
Lai, Cheng-Chang
;
Lin, Tzu-En
Interfacial mixing of polymers is a critical issue when attempting to improve the charge transport and stabilize the operation of solution-processed organic light-emitting diodes (OLEDs). Herein, we describe a simple methodology for overcoming interfacial mixing, based on the use of a photo-crosslinkable hole injection/transporting material (HITM). We synthesized a conjugated polymer, PTCAzide, bearing ready crosslinking ability and investigated its suitability for use as an HITM. Photo-crosslinking of the PTCAzide copolymer gave X-PTCAzide, which exhibited much higher thermal stability (the glass transition temperature increased by 21 K relative to that of PTCAzide), remarkable electrochemical stability, and excellent solvent-resistance, thereby expanding the operation time of corresponding electronic devices. Such a tris(8-hydroxy-quinolinato) aluminum-based trilayer device reached a maximum brightness of 52 971 cd m(-2), and the maximum luminance efficiency (LE) and power efficiency (eta E) are both higher than those of the corresponding device based on commercial PEDOT:PSS. In addition, a solution-processed phosphorescent OLED device incorporating X-PTCAzide also exhibited good performance (external quantum efficiency: 7.93%; LE: 29.6 cd A(-1); eta E: 14.3 lm W-1; maximum brightness: 34484 cd m(-2)). The efficient and simple photocrosslinking without adding an initiator could facilitate the fabrication process. Thus, PTCAzide appears to be a promising next-generation HITM for the development of highly efficient and inexpensive OLEDs. Its photo-crosslinkable nature allows improvements in morphological stability and hole injection/transporting ability, leading to more stable devices with better operation, without disrupting molecular packing or charge transport.
Bioinspired hole-conducting polymers for application in organic light-emitting diodes
(2012)
Cheng, Chih-Chia
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Chu, Yu-Lin
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Huang, Pei-Hsiu
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Yen, Ying-Chieh
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Chu, Chih-Wei
A novel uracil-functionalized poly(3-thiophene) as a hole-injecting/transporting layer in an organic light-emitting device is able to form physical crosslinkages resulting in high thermal stability, non-corrosion, excellent hole injection/transport and electron-blocking capabilities in the solid state, and it achieves up to 10 times higher performance than that of conventional poly(3-thiophene)s under similar experimental conditions.
Large-scale production of ureido-cytosine based supramolecular polymers with well-controlled hierarchical nanostructures
(2015-01-01)
Cheng, Chih-Chia
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Chang, Feng-Chih
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Wang, Jui-Hsu
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Chu, Yu-Lin
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Wang, Yeh-Sheng
A novel supramolecular polymer containing urea-cytosine (UrCy) quadruple hydrogen-bonding moieties that possesses a high association constant (K-a > 10(6) M-1) was synthesized at high yield (96%) at kilogram-scale. The synthesized telechelic macromer dissolved in solution can undergo a substantial change in solution viscoelasticity and can self-assemble due to the noncovalent nature of supramolecular polymerization. As the concentration of UrCy in solution was increased, the spherical assemblies gradually transformed to an ordered lamellar phase with an extremely high degree of polymerization. In addition, the dynamic behavior of UrCy units induced a sudden phase transition in the bulk state, revealing an interesting order-disorder transition from a crystalline solid to liquid state. This newly-discovered material has excellent polymer-like features that are distinct to existing systems. A simple path for forming supramolecular polymers is recommended for the design, large-scale production and manipulation of self-assembled materials with distinctive properties.
New bioinspired hole injection/transport materials for highly efficient solution-processed phosphorescent organic light-emitting diodes
(2015-04-01)
Cheng, Chih-Chia
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Chu, Yu-Lin
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Chang, Feng-Chih
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Lee, Duu-Jong
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Yen, Ying-Chieh
A new concept to supramolecular assembly of existed functional polymers, capable of forming network-like organizational clusters through multiple hydrogen-bonding interactions has been exploited. In this paper, a new adenine-based poly(triphenylamine-carbazole) (PTC-A) has been prepared which exhibits a high self-complementary ability in solution and solid states owing to the formation of adenine-adenine (A-A) pairs by induced hierarchical self-assembly. Comparing with uracil-substituted PTC sample (PTC-U), PTC-A presents a much higher thermal stability, electrochemical stability and solvent-resistance ability due to the formation of the more stable physically cross-linking structure. When the PTC-A is utilized as a hole injection/transport layer in a trilayer OLED device, a remarkable improvement in performance relative to the control PTC and PTC-U under similar experimental conditions has been achieved. Further comparison with a control device using a conventional PEDOT:PSS, the efficiency of the solution-processed phosphorescent PLED device with PTC-A is significantly higher than those of PTC-U and PEDOT: PSS-based devices. Thus, PTC-A represents the next-generation hole injection/transport material for high efficiency LED device and low-cost fabrication process. (C) 2015 Elsevier Ltd. All rights reserved.
Photo-Crosslinking of Pendent Uracil Units Provides Supramolecular Hole Injection/Transport Conducting Polymers for Highly Efficient Light-Emitting Diodes
(2015-05-01)
Shih, Hsi-Kang
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Chen, Yi-Han
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Chu, Yu-Lin
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Cheng, Chih-Chia
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Chang, Feng-Chih
A new process for modifying a polymeric material for use as a hole injection transport layer in organic light-emitting diodes has been studied, which is through 2 + 2 photodimerization of a DNA-mimetic -conjugated poly(triphenylamine-carbazole) presenting pendent uracil groups (PTC-U) under 1 h of UV irradiation. Multilayer florescence OLED (Organic light-emitting diodes) device with the PTC-U-1hr as a hole injection/transport layer (ITO (Indium tin oxide)/HITL (hole-injection/transport layer) (15 nm)/N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB) (15 nm)/Tris-(8-hydroxyquinoline)aluminum (Alq(3)) (60 nm)/LiF (1 nm)/Al (100 nm)) is fabricated, a remarkable improvement in performance (Q(max) (external quantum efficiency) = 2.65%, B-max (maximum brightness) = 56,704 cd/m(2), and LE (luminance efficiency)(max) = 8.9 cd/A) relative to the control PTC-U (Q(max) = 2.40%, B-max = 40,490 cd/m(2), and LEmax = 8.0 cd/A). Multilayer phosphorescence OLED device with the PTC-U-1hr as a hole injection/transport layer (ITO/HITL (15 nm)/Ir(ppy)(3):PVK (40 nm)/BCP (10nm)/Alq(3) (40 nm)/LiF (1 nm)/Al (100 nm)) is fabricated by successive spin-coating processes, a remarkable improvement in performance (Q(max) = 9.68%, B-max = 41,466 cd/m(2), and LEmax = 36.6 cd/A) relative to the control PTC-U (Q(max) = 8.35%, B-max = 34,978 cd/m(2), and LEmax = 30.8 cd/A) and the commercial product (poly(3,4-ethylenedioxythiophene):polystyrenesulfonate) PEDOT:PSS (Q(max) = 4.29%, B-max = 15,678 cd/m(2), and LEmax = 16.2 cd/A) has been achieved.
Surface modification of poly(2-methoxy-5-(2 '-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) by confined photo-catalytic oxidation
(2012-02-15)
Yen, Ying-Chieh
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Cheng, Chih-Chia
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Wang, Yeh-Sheng
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Chu, Yu-Lin
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Lu, Chu-Hua
In this study, the surface of pi-conjugated polymer, poly(2-methoxy-5(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV), was successfully modified with the sulfate anion (SO4-) groups by the confined photo-catalytic oxidation (CPO). After the surface modification, the water contact angle of MEH-PPV is changed from 95.5 degrees to 82.1 degrees without influence on its optical properties (based on the UV and PL spectra), and the water droplet can be absorbed on the modified MEH-PPV surface without sliding even at substrate tilt angles of 90 degrees and 180 degrees. The CPO on the MEH-PPV surface is able to further expand the use of MEH-PPV for applications. In addition, the water transport test indicates that the modified MEH-PPV can be a candidate for transporting water droplet. (C) 2011 Elsevier Inc. All rights reserved.