Browsing by Author "Hsu, Fang-Ming"

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A Bipolar Host Material Containing Triphenylamine and Diphenylphosphoryl-Substituted Fluorene Units for Highly Efficient Blue Electrophosphorescence
(2009-09-09)
Hsu, Fang-Ming
;
Chien, Chen-Han
;
Shu, Ching-Fong
;
Lai, Chin-Hung
;
Hsieh, Cheng-Chih
Highly efficient blue electrophosphorescent organic light-emitting diodes incorporating a bipolar host, 2,7-bis(diphenylphosphoryl)-9-[4-(N,N-diphenylamino)phenyl]-9-phenylfluorene (POAPF), doped with a conventional blue triplet emitter, iridium(III) bis[(4,6-difluorophenyl)pyridinato-N,C(2)]picolinate (FIrpic) are fabricated. The molecular architecture of POAPF features an electron-donating (p-type) triphenylamine group and an electron-accepting (n-type) 2,7-bis(diphenylphosphoryl)fluorene segment linked through the sp(3)-hybridized C9 position of the fluorene unit. The lack of conjugation between these p- and n-type groups endows POAPF with a triplet energy gap (ET) of 2.75 eV, which is sufficiently high to confine the triplet excitons on the blue-emitting guest. In addition, the built-in bipolar functionality facilitates both electron and hole injection. As a result, a POAPF-based device doped with 7 wt% FIrpic exhibits a very low turn-on voltage (2.5 V) and high electroluminescence efficiencies (20.6% and 36.7 lm W(-1)). Even at the practical brightnesses of 100 and 1000cd m(-2), the efficiencies remain high (20.2%/33.8 lm W(-1) and 18.8%/24.3 lm W(-1), respectively), making POAPF a promising material for use in low-power-consumption devices for next-generation flat-panel displays and light sources.
Antibacterial polypeptide/heparin composite hydrogels carrying growth factor for wound healing
(2020-07-01)
Hsu, Fang-Ming
;
Hu, Ming-Hsien
;
Jiang, Yi-Sheng
;
Lin, Bi-Yun
;
Hu, Jin-Jia
We report an efficient growth factor delivering system based on polypeptide/heparin composite hydrogels for wound healing application. Linear and star-shaped poly(L-lysine) (l-PLL and s-PLL) were chosen due to not only their cationic characteristics, facilitating the efficient complexation of negatively charged heparin, but also the ease to tune the physical and mechanical properties of as-prepared hydrogels simply by varying polypeptide topology and chain length. The results showed that polymer topology can be an additional parameter to tune hydrogel properties. Our experimental data showed that these composite hydrogels exhibited low hemolytic activity and good cell compatibility as well as excellent antibacterial activity, making them ideal as wound dressing materials. Unlike other heparin-based hydrogels, these composite hydrogels with heparin densely deposited on the surface can increase the stabilization and concentration of growth factor, which can facilitate the healing process as confirmed by our in vivo animal model. We believe that these PLL/heparin composite hydrogels are promising wound dressing materials and may have potential applications in other biomedical fields.
Efficient non-doped blue-light-emitting diodes incorporating an anthracene derivative end-capped with fluorene groups
(2009)
Wu, Chen-Hao
;
Chien, Chen-Han
;
Hsu, Fang-Ming
;
Shih, Ping-I
;
Shu, Ching-Fong
We have synthesized and characterized a novel blue-emitting material, 2-tert-butyl-9,10-bis[40-(9-ptolylfluoren- 9-yl) biphenyl-4-yl] anthracene (BFAn), containing an anthracene core end-capped with 9-phenyl-9-fluorenyl groups. The presence of the sterically congested fluorene groups imparts BFAn with a high thermal decomposition temperature (T(d) = 510 degrees C) and results in its forming a stable glass (T(g) = 227 degrees C). Atomic force microscopy measurements revealed that BFAn forms high-quality amorphous films and possesses good morphological stability after annealing. Organic light-emitting diodes (OLEDs) featuring BFAn as the emitter exhibited an excellent external quantum efficiency of 5.1% (5.6 cd A(-1)) with Commission Internationale de L'Eclairage coordinates of (0.15, 0.12) that are very close to the National Television Standards Committee's blue standard. The power efficiency of our BFAn-based devices reached as high as 5.7 lmW(-1), making them superior to other reported non-doped deep-blue OLEDs.
Efficient red electrophosphorescence from a fluorene-based bipolar host material
(2009-08-01)
Chien, Chen-Han
;
Hsu, Fang-Ming
;
Shu, Ching-Fong
;
Chi, Yun
;
應用化學系
We have prepared efficient red organic light-emitting diodes (OLEDs) incorporating 2,7-bis(diphenylphosphoryl)-9-[4-(N,N-diphenylamino)phenyl]-9-phenylfluorene (POAPF) as the host material doped with the osmium phosphor Os(fptz)(2)(PPh(2)Me)(2) (fPtZ = 3-trifluoromethyl-5-pyridyl-1,2,4-triazole). POAPF, which possesses bipolar functionalities, can facilitate both hole- and electron-injection from the charge transport layers to provide a balanced charge flux within the emission layer. The peak electroluminescence performance of the device reached as high as 19.9% and 34.5 lm/W - the highest values reported to date for a red phosphorescent OLED. In addition, we fabricated a POAPF-based white light OLED - containing red-[doped with OS(fPtZ)(2)(PPh(2)Me)(2)] and blue-emitting [doped with iridium(III) bis[(4,6-difluorophenyl)pyridinato-N,C(2')] picolinate, Firpic} layers - that also exhibited satisfactory efficiencies (18.4% and 43.9 lm/W). (C) 2009 Elsevier B.V. All rights reserved.
High morphology stability and ambipolar transporting host for use in blue phosphorescent single-layer organic light-emitting diodes
(2014-11-01)
Hsu, Fang-Ming
;
Chien, Liang-Jung
;
Chen, Kuan-Ting
;
Li, Ya-Ze
;
Liu, Shun-Wei
The authors report a small molecule host of 2,7-bis(diphenylphosphoryl)-9-[4-(N, N-diphenylamino)phenyl]-9-phenylfluorene (POAPF) doped with 8 wt% iridium(III)-bis[(4,6-difluorophenyl)pyridinato-N,C-2\']picolinate (FIrpic) for use in efficient and single-layer blue phosphorescent organic light-emitting diodes (PHOLEDs) exhibiting a maximum external quantum efficiency of similar to 20.3% at brightness of 100 cd/m(2). The high performance of such single layer PHOLEDs is attributed to the POAPF host\'s high morphological stability, suitable triplet energy level, and equal charge carrier mobilities of hole and electron to form the broad carrier recombination zone in the emitting layer, thus reducing the triplet-triplet annihilation and resulting in a slight efficiency roll off of 0.5% from the brightness of 1 and 1000 cd/m(2). This work also systematically investigated the arrangement of the POAPF:FIrpic recombination zone for optimizing the performance of the single layer PHOLED. (C) 2014 Elsevier B.V. All rights reserved.
Highly efficient red electrophosphorescent device incorporating a bipolar triphenylamine/bisphenylsulfonyl-substituted fluorene hybrid as the host
(2009)
Hsu, Fang-Ming
;
Chien, Chen-Han
;
Hsieh, Ya-Jou
;
Wu, Chen-Hao
;
Shu, Ching-Fong
We have fabricated highly efficient red phosphorescent organic light-emitting diodes (PHOLEDs) incorporating a bipolar host material, 2,7-bis(phenylsulfonyl)-9-[4-(N,N-diphenylamino)phenyl]-9-phenylfluorene (SAF), doped with 7 wt% tris(1-phenylisoquinolinolato-C(2),N)iridium(III) [Ir(piq)(3)]. Attaching the electron-donating (p-type) triphenylamine group onto the electron-accepting (n-type) 2,7-bis(phenylsulfonyl)fluorene segment (through the C9 position of the fluorene unit) imparts SAF with good morphological stability, high triplet energy gap (ET), bipolar transporting ability, and matching energy levels with adjacent carrier-transporting layers. Consequently, the SAF-based red-PHOLED exhibited a very low turn-on voltage (2.4 V) and high electroluminescence efficiencies of 15.8% and 22.0 lm W(-1), superior to those of the corresponding device incorporating a conventional host material, 4,4'-N,N'-dicarbazolbiphenyl (CBP; 3.2 V, 8.5%, and 8.4 lm W(-1), respectively). At a practical brightness of 1000 cd m(-2), the efficiencies of the SAF-based red-PHOLED remained high (13.1%, 14.4 lm W(-1)).
Multifunctional Deep-Blue Emitter Comprising an Anthracene Core and Terminal Triphenylphosphine Oxide Groups
(1970-01-01)
Chien, Chen-Han
;
Chen, Ching-Kun
;
Hsu, Fang-Ming
;
Shu, Ching-Fong
;
Chou, Pi-Tai
"A highly efficient blue-light emitter, 2-tert-butyl-9,10-bis[4'-diphenyl-phosphoryl)phenyl]anthracene (POAn) is synthesized, and comprises electron-deficient triphenylphosphine oxide side groups appended to the 9- and 10-positions of a 2-tert-butylanthracene core. This sophisticated anthracene compound possesses a non-coplanar configuration that results in a decreased tendency to crystallize and weaker intermolecular interactions in the solid state, leading to its pronounced morphological stability and high quantum efficiency. In addition to serving as an electron-transporting blue-light-emitting material, POAn also facilitated electron injection from the Al cathode to itself. Consequently, simple double-layer devices incorporating POAn as the emitting, electron-transporting, and -injecting material produce bright deep-blue lights having Commission Internationale de L'Eclairage coordinates of (0.15,0.07). The peak electroluminescence performance was 4.3% (2.9 cd A(-1)). For a device lacking an electron-transport layer or alkali fluoride, this device displays the best performance of any such the deep-blue organic light-emitting diodes reported to date."
Phosphine-Oxide-Containing Bipolar Host Material for Blue Electrophosphorescent Devices
(1970-01-01)
Hsu, Fang-Ming
;
Chien, Chen-Han
;
Shih, Ping-I
;
Shu, Ching-Fong
;
應用化學系
"We report highly efficient blue electrophosphorescent organic light-emitting diodes (OLEDs) incorporating a bipolar host, 2,7-bis(diphenylphosphine oxide)-9-(9-phenylcarbazol-3-yl)-9-phenylfluorene (PCF), doped with iridium(III) bis[(4,6-difluorophenyl)pyridinato-NC2']picolinate (FIrpic). PCF, which contains diphenylphosphine oxide groups appended onto a carbazole/fluorene hybrid, displays both electron- and hole-tran sporting characteristics, resulting in a low turn-on voltage (2.6 V) and greatly improved power efficiencies. In addition, the sterically hindered structure of PCF provides a compatible environment for the FIrpic dopant, alleviating concentration quenching of the phosphor at high doping levels. The device doped with 28 wt % FIrpic exhibited maximum EL efficiencies of 30.8 cd/A and 26.2 lm/W (at 121 cd/m(2)) /m(2), Even at a high brightness of 1000 cd/m(2) the efficiencies remained high (26.9 cd/A and 19.6 lm/W)."