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Multilayer Polymer Light-Emitting Diodes: White-Light Emission With High Efficiency, Xiong Gong
Multilayer Polymer Light-Emitting Diodes: White-Light Emission With High Efficiency, Xiong Gong
Xiong Gong
This work was jointly supported by Mitsubishi Chemical Center for Advanced Materials at UC Santa Barbara, by Air Force Office of Scientific Research through the MURI Center (“Polymeric Smart Skins”, AFOSRF 49620-01-10364), Program Officer, Dr. Charles Lee. We thank Dr. Gang Yu of Dupont Displays for advice on calculating the CIE coordinates, Dr. Yoshiharu Sato at the Science & Technology Research Center of Mitsubishi Chemical Corporation in Japan for useful discussions, Dr. Steven Xiao at Organic Vision, Inc. (Canada) for providing the conjugated polymers, and Dr. Jack Ostrowski at UC Santa Barbara for synthesis of Ir-complex.
Bulk Heterojunction Solar Cells With Large Open-Circuit Voltage: Electron Transfer With Small Donor-Acceptor Energy Offset, Xiong Gong
Xiong Gong
Photoinduced electron transfer is observed in polymer bulk heterojunction solar cells with very small interfacial energy offset. The results imply that open circuit voltage values close to the band gap of the semiconducting polymer should be possible for polymer bulk heterojunction solar cells just as for inorganic solar cells.
Stabilization Of Semiconducting Polymers With Silsesquioxane, Xiong Gong
Stabilization Of Semiconducting Polymers With Silsesquioxane, Xiong Gong
Xiong Gong
Polyhedral oligomeric silsesquioxanes (POSS) anchored to poly(2-methoxy-5-(2-ethylhexyloxy)-1.4-phenylenevinylene) (MEH-PPV) (MEH-PPV–POSS), and to poly(9,9-dihexylfluorenyl-2,7-diyl) (PFO) (PFO–POSS) were synthesized. Compared with the corresponding parent polymers, MEH-PPV and PFO, MEH-PPV–POSS and PFO–POSS have better thermal stability. MEH-PPV–POSS and MEH-PPV have identical absorption and photoluminescent (PL) spectra, both in solution and as thin films. They also have identical electroluminescent (EL) spectra. Devices made from MEH-PPV–POSS exhibit higher brightness (1320 cd m–2 at 3.5 V) and higher external quantum efficiency (ηext = 2.2 % photons per electron) compared to MEH-PPV (230 cd m–2 at 3.5 V and ηext = 1.5 % ph el–1). Compared with PFO …
Biosensors From Conjugated Polyelectrolyte Complexes, Xiong Gong
Biosensors From Conjugated Polyelectrolyte Complexes, Xiong Gong
Xiong Gong
n this paper, we report an investigation of the PL from a conjugated polyelectrolyte complex in aqueous solution. We show that the anionic conjugated polymer alone is subject to nonspecific effects on the PL (luminescence enhancement), which complicates the use of conjugated polyelectrolytes in biosensing applications. We find, however, that when a cationic polymer is added in the solution to associate with the anionic conjugated polyelectrolyte and form a charge neutral complex (CNC) [formed in aqueous solution by an anionic conjugated polyelectrolyte and a saturated cationic polyelectrolyte at a 1:1 ratio (per repeat unit)], the CNC shows little evidence of …
Electrophosphorescence From A Conjugated Copolymer Doped With An Iridium Complex: High Brightness And Improved Operational Stability, Xiong Gong
Xiong Gong
High efficiency electrophosphorescent light-emitting diodes (LEDs), with an emission peak at 600 nm, a luminance of 2200 cd m–2, and good operational stability were fabricated from a conjugated copolymer doped with an iridium complex. The devices exhibited an external quantum efficiency of 1.5 % and a luminous efficiency of 3 cd A–1. These results demonstrate that electrophosphorescent devices with high brightness and operational stability can be produced in the form of polymer LEDs fabricated by processing the active materials from solution.
Modern Science And Technological English-Chinese Dictionary, Xiong Gong
Modern Science And Technological English-Chinese Dictionary, Xiong Gong
Xiong Gong
No abstract provided.
Long-Lifetime Polymer Light-Emitting Electrochemical Cells Fabricated With Crosslinked Hole-Transport Layers, Xiong Gong
Long-Lifetime Polymer Light-Emitting Electrochemical Cells Fabricated With Crosslinked Hole-Transport Layers, Xiong Gong
Xiong Gong
By inserting a crosslinkable hole-transport layer as the buffer layer between the single-phase polymer active layer and the anode of this new type of polymer light-emitting electrochemical cells (PLECs), the interface properties are improved and the PLECs can be operated with enhanced stability.
High-Detectivity Polymer Photodetectors With Spectral Response From 300 Nm To 1450 Nm, Xiong Gong
High-Detectivity Polymer Photodetectors With Spectral Response From 300 Nm To 1450 Nm, Xiong Gong
Xiong Gong
Sensing from the ultraviolet-visible to the infrared is critical for a variety of industrial and scientific applications. Today, gallium nitride–, silicon-, and indium gallium arsenide–-based detectors are used for different sub-bands within the ultraviolet to near-infrared wavelength range. We demonstrate polymer photodetectors with broad spectral response (300 to 1450 nanometers) fabricated by using a small-band-gap semiconducting polymer blended with a fullerene derivative. Operating at room temperature, the polymer photodetectors exhibit detectivities greater than 1012 cm Hz1/2/W and a linear dynamic range over 100 decibels. The self-assembled nanomorphology and device architecture result in high photodetectivity over this wide spectral range and …
Enhanced Efficiency Of Polymer Solar Cells By Magnetic Effects Science, Xiong Gong
Enhanced Efficiency Of Polymer Solar Cells By Magnetic Effects Science, Xiong Gong
Xiong Gong
No abstract provided.
Efficient, Air-Stable Bulk Heterojunction Polymer Solar Cells Using Moox As The Anode Interfacial Layer, Xiong Gong
Efficient, Air-Stable Bulk Heterojunction Polymer Solar Cells Using Moox As The Anode Interfacial Layer, Xiong Gong
Xiong Gong
The use of molybdenum oxide as the anode interfacial layer in conventional bulk heterojunction polymer solar cells leads to an improved power conversion efficiency and also dramatically increases the device stability. This indicates that the engineering of improved anode interface materials is an important method by which to fabricate efficient and stable polymer solar cells.
Electrophosphorescence From A Polymer Guest--Host System With An Iridium Complex As Guest: Forster Energy Transfer And Charge Trapping, Xiong Gong
Xiong Gong
This work was supported by the Mitsubishi Chemical Center for Advanced Materials at UCSB and the Air Force Office of Scientific Research through the MURI Center (“Polymeric Smart Skins”), Charles Lee, Program Officer. Synthesis of the iridium complexes was supported by a grant to G. Bazan from Kodak. X. Gong is grateful to Dr. Gang Yu of Dupont Displays for valuable discussion.
Synthesis And Characterization Of Polystyrene-Block-Polyisoprene Functionalized With Aromatic 1, 3, 4-Oxadiazoles By Metal Catalyzed Reaction, Xiong Gong
Xiong Gong
A series of polystyrene-block-polyisoprene functionalized with aromatic oxadiazoles have been synthesized by platinum catalyzed hydrosilation and palladium catalyzed Heck reaction. Transmission electron microscopic studies show that the copolymers exhibit microphase separation with a spherical microdomain. From the time-of-flight experimental results, the electron transport process is dispersive with the electron carrier mobilities of ˜10–4 cm2 V–1 s–1, which is comparable to some oxadiazole-doped polymer films.
End-Capping As A Method For Improving Carrier Injection In Electrophosphorescent Light-Emitting Diodes, Xiong Gong
End-Capping As A Method For Improving Carrier Injection In Electrophosphorescent Light-Emitting Diodes, Xiong Gong
Xiong Gong
The electronic properties, carrier injection, and transport into poly(9,9-dioctylfluorene) (PFO), PFO end-capped with hole-transporting moieties (HTM), PFO–HTM, and PFO end-capped with electron-transporting moieties (ETM), PFO–ETM, were investigated. The data demonstrate that charge injection and transport can be tuned by end-capping with HTM and ETM, without significantly altering the electronic properties of the conjugated backbone. End-capping with ETM resulted in more closely balanced charge injection and transport. Single-layer electrophosphorescent light-emitting diodes (LEDs), fabricated from PFO, PFO–HTM and PFO–ETM as hosts and tris[2,5-bis-2′-(9′,9′-dihexylfluorene)pyridine-κ2NC3′]iridium(III), Ir(HFP)3 as the guest, emitted red light with brightnesses of 2040 cd m–2, 1940 cd m–2 and 2490 cd …
High-Performance Polymer-Based Electrophosphorescent Light-Emitting Diodes, Xiong Gong
High-Performance Polymer-Based Electrophosphorescent Light-Emitting Diodes, Xiong Gong
Xiong Gong
High-performance electrophosphorescent light-emitting diodes (LEDs) were demonstrated with tris-[9,9-dihexyl-2-(pyridinyl-2′) fluorene] iridium(III) [Ir(DPF)3], tris-{9,9-dihexyl-2-[phenyl-4′-(-pyridin-2″-yl)] fluorene} iridium(III) [Ir(DPPF)3], and tris-[2,5-bis-2′-(9,9′-dihexylfluorene) iridium] [Ir(HFP)3] as guests and poly(vinylcarbazole) (PVK) blended with 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazol (PBD), poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), and poly(9,9-dihexylfluorene)-co-2,5-dicyanophenylene (PF3CNP1) as hosts. The devices made with PVK-PBD exhibited the highest external quantum efficiency (QEext), luminous efficiency (LE) and luminance (L). For example, yellowish green emission from PVK-PBD doped with Ir(DPF)3 was observed with QEext = 10% ph/el, LE = 36 cd/A, and L > 8300 cd/m2, and red emission from PVK-PBD doped with Ir(DPPF)3 was observed with QEext = 5% ph/el, LE = 7.2 cd/A, and L …
Quinoxaline-Based Conjugated Polymers Containing Ruthenium (Ii) Bipyridine Metal Complex, Xiong Gong
Quinoxaline-Based Conjugated Polymers Containing Ruthenium (Ii) Bipyridine Metal Complex, Xiong Gong
Xiong Gong
A series of novel quinoxaline-based conjugated polymers which contain a ruthenium(II) bipyridine complex were synthesized by the Suzuki coupling reactions. UV/VIS spectroscopy showed that the spectral features of the polymers are dependent on the amount of metal complex present. Results from excitation and emission spectroscopy suggest an energy transfer between the backbone and the metal complex. The polymers exhibit hole carrier mobilities of ≈ 10−5 cm2 · V−1 · s−1, which is comparable to organic photoconductors.
Semiconducting Polymer Photodetectors With Electron And Hole Blocking Layers: High Detectivity In The Near-Infrared, Xiong Gong
Xiong Gong
Sensing from the ultraviolet-visible to the infrared is critical for a variety of industrial and scientific applications. Photodetectors with broad spectral response, from 300 nm to 1,100 nm, were fabricated using a narrow-band gap semiconducting polymer blended with a fullerene derivative. By using both an electron-blocking layer and a hole-blocking layer, the polymer photodetectors, operating at room temperature, exhibited calculated detectivities greater than 1013 cm Hz1/2/W over entire spectral range with linear dynamic range approximately 130 dB. The performance is comparable to or even better than Si photodetectors.
Mimicking The Binding And Unbinding Of Fe3+ With Transferrin Using A Single Biomimetic Nanochannel, Chao Zhao, Xiaosi Li, Lingyan Li, Xiong Gong, Yung Chang, Jie Zheng
Mimicking The Binding And Unbinding Of Fe3+ With Transferrin Using A Single Biomimetic Nanochannel, Chao Zhao, Xiaosi Li, Lingyan Li, Xiong Gong, Yung Chang, Jie Zheng
Xiong Gong
A new type of apo-Tf functionalized nanochannel is developed to achieve the specific and selective binding and unbinding of Fe3+ in a multiple and reversible manner via a protein-conformation-gating mechanism. This ion-responsive biomimetic nanochannel provides a simple, robust, and promising model for studying other biological processes.
Stabilized Blue Emission From Polyfluorene-Based Light-Emitting Diodes: Elimination Of Fluorenone Defects, Xiong Gong
Stabilized Blue Emission From Polyfluorene-Based Light-Emitting Diodes: Elimination Of Fluorenone Defects, Xiong Gong
Xiong Gong
This work was partially supported by the Mitsubishi Chemical Center for Advanced Materials at UCSB and the Air Force Office of Scientific Research through the MURI Center (“Polymeric Smart Skins”), Charles Lee, Program Officer. Synthesis of the CF3OXD and related tetrahedrally coordinated molecules was supported by a grant to G. Bazan from DuPont Displays. The XPS results were obtained by using the MRL (Material Research Laboratory at UCSB) Central Facilities supported by the National Science Foundation under DMR 96-32716. We thank Prof. W. R. Salaneck of Linköping University (Sweden) for important comments. X. Gong is grateful to Dr. Gang Yu …