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Articles 1 - 30 of 149
Full-Text Articles in Engineering
23% Enhanced Efficiency Of Polymer Solar Cells Processed With 1-Chloronaphthalene As The Solvent Additive Organic Electronics, Xiong Gong
Xiong Gong
No abstract provided.
Donor--Acceptor Conjugated Polymer Based On Naphtho [1, 2-C: 5, 6-C] Bis [1, 2, 5] Thiadiazole For High-Performance Polymer Solar Cells, Ming Wang, Xiaowen Hu, Peng Liu, Wei Li, Xiong Gong, Fei Huang, Yong Cao
Donor--Acceptor Conjugated Polymer Based On Naphtho [1, 2-C: 5, 6-C] Bis [1, 2, 5] Thiadiazole For High-Performance Polymer Solar Cells, Ming Wang, Xiaowen Hu, Peng Liu, Wei Li, Xiong Gong, Fei Huang, Yong Cao
Xiong Gong
Donor–acceptor conjugated polymers PBDT-DTBT and PBDT-DTNT, based on 2,1,3-benzothiadiazole (BT) and naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole (NT), have been designed and synthesized for polymer solar cells. NT contains two fused 1,2,5-thiadiazole rings that lower the band gap, enhance the interchain packing, and improve the charge mobility of the resulting polymer. Consequently, the NT-based polymer PBDT-DTNT exhibited considerably better photovoltaic performance with a power conversion efficiency (PCE) of 6.00% when compared with the BT-based polymer PBDT-DTBT, which gave a PCE of 2.11% under identical device configurations.
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.
Synthesis Of Tetrachloro-Azapentacene As An Ambipolar Organic Semiconductor With High And Balanced Carrier Mobilities, Cheng-Li Song, Chong-Bo Ma, Feng Yang, Wei-Jing Zheng, Hao-Li Zhang, Xiong Gong
Synthesis Of Tetrachloro-Azapentacene As An Ambipolar Organic Semiconductor With High And Balanced Carrier Mobilities, Cheng-Li Song, Chong-Bo Ma, Feng Yang, Wei-Jing Zheng, Hao-Li Zhang, Xiong Gong
Xiong Gong
Two new azapentacene derivatives 9,10-dibromo-6,13-bis(triisopropylsilylethynyl)-1-azapentacene (a) and 8,9,10,11-tetrachloro-6,13-bis(triisopropylsilylethynyl)-1-azapentacene (b) were synthesized, and their FET properties were investigated. Compound b exhibits high and balanced ambipolar transport properties, with the hole and electron mobilities reaching up to 0.12 and 0.14 cm2 V–1 s–1, respectively. This work suggests that chlorination to the N-heteropentacene framework is an efficient way for producing high performance ambipolar organic semiconductors.
White Light Electrophosphorescence From Polyfluorene-Based Light-Emitting Diodes: Utilization Of Fluorenone Defects, Xiong Gong
Xiong Gong
Poly(9,9-dioctylfluorene-co-fluorenone) with 1% fluorenone, (PFO−F(1%)), was synthesized as a model compound to investigate the optical and electrical effects of fluorenone defects in poly(9,9-dioctylfluoren-2,7-diyl), PFO. Photoluminescence (PL) and electroluminescence (EL) measurements demonstrate that PFO−F(1%) emits stable green light. PL and EL studies indicate that Förster energy transfer to and charge carrier trapping on fluorenone defects (with subsequent fluorenone emission) are responsible for the color degradation typically observed with the polyfluorenes. By utilization of “fluorenone defects” in PFO−fluorenone copolymers (PFO−F), white electrophosphorescent light-emitting diodes were fabricated. Polymer blends were spin-cast from solution containing PFO, PFO−F (1%), and tris[2,5-bis(9,9-dihexylfluoren-2-yl)pyridine-κ2NC3]iridium(III), Ir(HFP)3. The white emission …
Preparation, Structure And Ir Spectra Of Rare Earth Complex Oxides Nanocrystallines Re~ 2sn~ 2~-~ Xb'~ Xo~ 7 (Re= Sm, Ce; B'= Fe, Co, Nix; X= 0 Asymptotically Equal To 1.0), Xiong Gong
Xiong Gong
No abstract provided.
Printable Polymer Electronics, Xiong Gong
Zinc Oxide Nanowire As An Electron-Extraction Layer For Broadband Polymer Photodetectors With An Inverted Device Structure, Tingbin Yang, Ke Sun, Xilan Liu, Wei Wei, Tianzhi Yu, Xiong Gong, Deli Wang, Yong Cao
Zinc Oxide Nanowire As An Electron-Extraction Layer For Broadband Polymer Photodetectors With An Inverted Device Structure, Tingbin Yang, Ke Sun, Xilan Liu, Wei Wei, Tianzhi Yu, Xiong Gong, Deli Wang, Yong Cao
Xiong Gong
We report the fabrication of high-performance broadband polymer photodetectors based on narrow bandgap conjugated polymers with an inverted device structure, where electrons and holes are collected on indium tin oxide and metal contact with high work function. High-quality wide bandgap vertically aligned ZnO nanowire array offers an enhanced surface area and is used as the cathode buffer layer in this device for effectively extracting electrons and blocking holes from the active polymer layer. The room-temperature detectivity of polymer photodetectors with such an inverted device structure is greater than 1010 Jones with the spectral response from 400 to 1450 nm. Our …
Multilayer Led And Deposition Method, Xiong Gong
Solution Processed Infrared Polymer Photodetector, Xiong Gong
Solution Processed Infrared Polymer Photodetector, Xiong Gong
Xiong Gong
No abstract provided.
Fluids, Plasmas, And Electrical Discharges, Xiong Gong
Fluids, Plasmas, And Electrical Discharges, Xiong Gong
Xiong Gong
No abstract provided.
New Architecture For High-Efficiency Polymer Photovoltaic Cells Using Solution-Based Titanium Oxide As An Optical Spacer, Xiong Gong
Xiong Gong
Polymer photovoltaic cells with power conversion efficiencies approaching 5 % have been fabricated using titanium oxide (TiOx) as an optical spacer (see Figure). Solar cells with a TiOx layer (deposited via a sol–gel process) between the active layer and the electron-collecting aluminum electrode exhibit approximately a 50 % enhancement in short-circuit current compared to similar devices without the optical spacer, as a result of modification of the spatial distribution of the light intensity inside the device.
Methods And Devices Comprising Soluble Conjugated Polymers, Xiong Gong
Methods And Devices Comprising Soluble Conjugated Polymers, Xiong Gong
Xiong Gong
Methods, compositions and articles of manufacture involving soluble conjugated polymers are provided. The conjugated polymers have a sufficient density of polar substituents to render them soluble in a polar medium, for example water and/or methanol. The conjugated polymer may desirably comprise monomers which alter its conductivity properties. In some embodiments, the inventors have provided cationic conjugated polymers (CCPs) comprising both solubilizing groups and conductive groups, resulting in conductive conjugated polymers soluble in polar media. The different solubility properties of these polymers allow their deposition in solution in multilayer formats with other conjugated polymers. Also provided are articles of manufacture comprising …
Polymer White Light-Emitting Diodes, Xiong Gong
Solution-Processed Near-Infrared Polymer Photodetectors With An Inverted Device Structure, Xilan Liu, Hangxing Wang, Tingbin Yang, Wei Zhang, I-Fan Hsieh, Stephen Cheng, Xiong Gong
Solution-Processed Near-Infrared Polymer Photodetectors With An Inverted Device Structure, Xilan Liu, Hangxing Wang, Tingbin Yang, Wei Zhang, I-Fan Hsieh, Stephen Cheng, Xiong Gong
Xiong Gong
Solution-processed near-infrared polymer photodetectors with an inverted device structure were designed and fabricated. By introducing ZnOx and MoO3 as an electron extraction layer and a hole extraction layer, respectively, the asymmetric characteristics of the inverted polymer photodetectors was constructed. Operating at room temperature, the inverted polymer photodetectors exhibited the detectivity over 1012 cm Hz1/2/W from 400 to 850 nm, resulting from the enhanced photocurrent and reduced dark current induced by fabricating photoactive layer from solution with processing additive 1,8-diiodooctane. These device performances were comparable to those of inorganic counterparts.
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.
Multilayer Polymer Light-Emitting Diodes For Solid State Lighting Applications, Xiong Gong
Multilayer Polymer Light-Emitting Diodes For Solid State Lighting Applications, Xiong Gong
Xiong Gong
Multilayer polymer light-emitting diodes (PLEDs) are demonstrated using semiconducting polymers blended with organometallic emitters as the emissive layer and one or both of an electron transport layer and a hole transparent layer on the appropriate electron injection and hole injection sides of the emissive layer. The transport layers reduce energy potential gaps between the hole injection electrode and the emissive polymer and between the electron injection electrode and the emissive polymer. A solvent-processing based procedure for preparing these devices is also disclosed It uses nonpolar solvent-based solutions of emissive polymers to form the emissive layer and polar solvent-based solutions to …
Towards High Performance Inverted Polymer Solar Cells, Xiong Gong
Towards High Performance Inverted Polymer Solar Cells, Xiong Gong
Xiong Gong
Bulk heterojunction (BHJ) polymer solar cells (PSCs) that can be fabricated by solution processing techniques are under intense investigation in both academic institutions and industrial companies because of their potential to enable mass production of flexible and cost-effective alternative to silicon-based solar cells. A combination of novel polymer development, nanoscale morphology control and processing optimization has led to over 8% of power conversion efficiencies (PCEs) for BHJ PSCs with a conventional device structure. Attempts to develop PSCs with an inverted device structure as required for achieving high PCEs and good stability have, however, met with limited success. Here, we report …
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 …
Novel Silafluorene-Based Conjugated Polymers With Pendant Acceptor Groups For High Performance Solar Cells, Xiong Gong
Novel Silafluorene-Based Conjugated Polymers With Pendant Acceptor Groups For High Performance Solar Cells, Xiong Gong
Xiong Gong
Two low-band-gap conjugated polymers, PSiFDCN and PSiFDTA, which consist of alternating silafluorene and triphenylamine backbone and different pendant acceptor groups (malononitrile and 1,3-diethyl-2-thiobarbituric acid) with styrylthiophene as π-bridge, were synthesized and characterized. By changing the acceptor groups in side chain, the energy levels, absorption spectra, and band gaps of the resulted polymers were effectively tuned. As the strength of the acceptors increases, the band gap reduces from 1.83 eV for PSiFDCN to 1.74 eV for PSiFDTA. Bulk heterojunction solar cells with these polymers as electron donor and (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) as electron acceptor exhibit high Voc (>0.85 …
Image Storage Based On Biphotonic Holography In Azo/Polymer System, Xiong Gong
Image Storage Based On Biphotonic Holography In Azo/Polymer System, Xiong Gong
Xiong Gong
Image storage has been investigated with the biphotonic holographic method in an azo/polymer film. Experimental results show that this biphotonic holographic storage has high spatial resolution and exhibits an image enhancement effect after blocking the noncoherent light. The mechanism of biphotonic holographic storage is attributed to the redistribution of cis form azo molecules induced by both coherent light and noncoherent light.
System And Methods For Improving The Qualities Of Polymer Light-Emitting Electrochemical Cells, Xiong Gong
System And Methods For Improving The Qualities Of Polymer Light-Emitting Electrochemical Cells, Xiong Gong
Xiong Gong
A light-emitting device comprising a pair of electrodes, and an emitting polymer active layer between the pair of electrodes, and either a) an electron transport layer, b) a hole transport layer, or c) a low work function material layer, wherein said emitting polymer layer comprising a single phase combination of a light-emitting polymer and an ionic liquid, is provided. Such multilayered devices have increased stability at relatively high voltages, fast turn-on times, low operating voltage, high brightness and long lifetimes.
Enhanced Electron Injection In Polymer Light-Emitting Diodes: Polyhedral Oligomeric Silsesquioxanes As Dilute Additives, Xiong Gong
Xiong Gong
By blending monochlorocyclohexyl- polyhedral oligomeric silsesquioxanes (MCC-POSS) into poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1.4-phenylenevinylene (MEH-PPV), enhanced luminous efficiency (LE, cd A−1) and brightness were observed in polymer light-emitting diodes (PLEDs) using Al as the cathode. PLEDs made from MEH-PPV with 0.5 wt.% of MCC-POSS exhibit LE of 1 cd A−1, four times higher than that observed in simple MEH-PPV devices. x-ray diffraction studies, measurements of photovoltaic response and measurements of photoconductivity from the films of pure MEH-PPV and MEH-PPV with MCC-POSS demonstrated that the improved device performance results from mixing of MCC-POSS with MEH-PPV. The enhanced electron-injection into the emissive layer results from the effect …
Strain And Huckel Aromaticity: Driving Forces For A Promising New Generation Of Electron Acceptors In Organic Electronics, Xiong Gong
Xiong Gong
Straining at the leash: The main features of electron-accepting materials with a 9,9′-bifluorenylidene backbone are strain relief and a gain in aromaticity. These dimers (see picture) exhibit absorption near the red spectral region (ca. 600 nm) and HOMO (5.58–5.06 eV) and LUMO (3.37–3.09 eV) energy levels, which, together with high solubility and thermal stability render these materials attractive acceptors for bulk heterojunction (BHJ) solar cells.
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 …
High Performance Polymer Light-Emitting Diodes Fabricated With A Novel Hole Injection Layer, Xiong Gong
High Performance Polymer Light-Emitting Diodes Fabricated With A Novel Hole Injection Layer, Xiong Gong
Xiong Gong
Enhanced luminance (L) and luminous efficiency (LE) of polymer light-emitting diodes (PLEDs) is demonstrated using poly (bis (tetraphenyldiamino)biphenyl-perfluorocyclobutane), poly(BTPD-Si-PFCB), as the hole injection layer. The monomer is cast directly onto the indium-tin-oxide anode and thermally polymerized in situ. Hole injection from poly(BTPD-Si-PFCB) into the Â"super yellowÂ" derivative of poly(phenylene vinylene) and into several blue emitting polymers is comparable to or better than that from poly(enthylendioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSSA). With poly(BTPD-Si-PFCB) as the hole injecting layer into super yellow, the performance is identical to that obtained with PEDOT:PSSA (LE » 8 cd/A with little fall-off even at L > 104 cd/m2). For …
Preparation And Photoluminescence Of Nanocrystalline Mso 4: Xtb 3+(M= Ca, Sr, And Ba; X= 0.001--0.005), Xiong Gong
Preparation And Photoluminescence Of Nanocrystalline Mso 4: Xtb 3+(M= Ca, Sr, And Ba; X= 0.001--0.005), Xiong Gong
Xiong Gong
A series of nanocrystalline MSO4:xTb3+ (M=Ca, Sr, and Ba; x=0.001-0.005) samples have been prepared by the co-precipitation method following low-temperature treatment. The x-ray diffraction technique yielded an average grain size of approximately 24 nm. Based upon the experimental data and theoretical calculations, it is concluded that the photoluminescence quenching in nanocrystalline MSO4:xTb3+ results from the dipole-quadrupole interaction.
Polymer Solar Cells, Xiong Gong
An Electrochemical Super Sandwich Assay For Sensitive And Selective Dna Detection In Complex Matrices, Xiong Gong
An Electrochemical Super Sandwich Assay For Sensitive And Selective Dna Detection In Complex Matrices, Xiong Gong
Xiong Gong
In a traditional sandwich assay, a DNA target hybridizes to a single copy of the signal probe. Here we employ a modified signal probe containing a methylene blue (a redox moiety) label and a “sticky end.” When a DNA target hybridizes this signal probe, the sticky end remains free to hybridize another target leading to the creation of a supersandwich structure containing multiple labels. This leads to large signal amplification upon monitoring by voltammetry.
Polymer Solar Cells With Larger Open-Circuit Voltage, Xiong Gong
Polymer Solar Cells With Larger Open-Circuit Voltage, Xiong Gong
Xiong Gong
No abstract provided.