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A fully soluble and photo-crosslinkable gate dielectric (6 F-SPI-Cinnamoyl: 6 F-SPI-CM) was synthesized. First, hydroxyl group substituted polyimide (6 F-SPI-Hydroxyl: 6 F-SPI-OH) polymer was prepared using monomers, 5-(2,5-dioxytetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOCDA) and 4,4'-(perfluoropropane-2,2-diyl)dianiline (6FHAB) through polycondensation reaction. And, then 6 F-SPI-OH was further reacted with cinnamoyl chloride to prepare a photo-crosslinkable 6 F-SPI-CM. The thin film of photo-crosslinked 6 F-SPI-CM (C-6F-SPI-CM) showed the extremely low leakage current density of <1.0 x10−11 A/cm2. In addition, 6 F-SPI-CM was easily patterned by selective UV-light exposure. A flexible pentacene thin-film transistor (TFT) on polyethersulfone (PES) substrate with photo-crosslinked 6 F-SPI-CM as a gate dielectric showed a field effect mobility of 0.11 cm2/Vs with no hysteresis behavior. [ABSTRACT FROM AUTHOR]

In this study, we applied a strategy which is systematically varying the central' core in non-fused NFA structure to modulate the optical-electrochemical properties and photovoltaic performance. The optical and structural calculation was analyzed via UV–Vis spectroscopy and DFT calculation. The results exhibit that strong NIR absorption and good planar backbone structure on those non-fused NFAs. Consequently, photovoltaic device based on TT linked acceptor delivered a promising photovoltaic efficiency of 8.37% for as-cast device. These results suggest that the change of central unit is an effective strategy to improve the optoelectronic properties of non-fused NFAs in organic solar cells. [ABSTRACT FROM AUTHOR]

Fluorination has been established as an effective structural modification strategy to influence properties and has attracted attention in organic solar cells. Here, we design and synthesize three fused‐ring electron acceptors based on ladder‐type pentacyclic heteroacenes as the electron‐rich unit and 1,1‐dicyanomethylene‐3‐indanones with 0–2 fluorine substituents as the electron‐deficient units. Among these three molecules, two fluorine substituents nonfullerene acceptor, DTP‐2F exhibit strong absorption with high extinction coefficients and deep HOMO and LUMO level as compared with DTP‐0F and DTP‐1F. Device studies show that fluorinated nonfullerene acceptors (NFAs) lead to reduced VOC but increased JSC and FF, and therefore, the ultimate influence to efficiency depends on the compensation of VOC loss and gains of JSC and FF. Furthermore, fluorination affect to film morphology and miscibility between donor and acceptor. The fluorination of NFAs is one of the best design method of the donor and acceptor materials for efficient high‐performance organic solar cell. [ABSTRACT FROM AUTHOR]

A new alkoxy substituted phenyl-containing hyperbranched conjugated poly(phenylene vinylene) (Hyper-PMEH-PPV) has been synthesized through the well-known Wittig polycondensation reaction. The synthesized Hyper-PMEH-PPV was completely soluble in common organic solvents and exhibited good thermal stability up to 383 °C. The photophysical properties of Hyper-PMEH-PPV are investigated and compared with a linear conjugated poly(para-phenylene vinylene) (Linear-PMEH-PPV) and well-known MEH-PPV. An absorption maximum of Hyper-PMEH-PPV film was determined at 395 nm which was far blue-shifted than that of Linear-PMEH-PPV (428 nm). Hyper-PMEH-PPV film showed green photoluminescence (PL) peak at 513 nm. In addition, Hyper-PMEH-PPV film exhibited almost no excimer or aggregate emission peaks even when the polymer film was annealed at 80 °C for 30 min in air condition. No undesirable emissions from Hyper-PMEH-PPV film are due to the inhibition of intermolecular interaction by the introduction of the hyperbranched network into the poly(phenylene vinylene) backbone. [ABSTRACT FROM AUTHOR]

A new wide bandgap (WBG) conjugated polymer diO-PBDB-T containing alkoxy substituted thiophene spacer was designed and synthesized for application as a donor in nonfullerene acceptor (NFA) based polymer solar cells (PSCs), to investigate the effect of alkoxy substitution on the photovoltaic performance. The suggested polymer diO-PBDB-T showed good complementary absorption spectra with a bandgap of 1.96 eV, a highest occupied molecular orbital (HOMO) energy level of −5.4 eV. The diO-PBDB-T:Y6-based PSCs exhibit a much higher power conversion efficiency (PCE) of 4.26%. These results suggest that alkoxy substitution is an effective strategy to improve the optoelectronic properties of WBG polymers in NFA-PSCs. [ABSTRACT FROM AUTHOR]

Herbal medicine is widely prescribed worldwide. To date, however, studies on the prediction of efficacy of herbal medicine based on machine learning have very rarely been reported. The objectives of this study are to predict the efficacy of Taeumjowi-tang (one of herbal medicines) and evaluate the prediction model in treating metabolic abnormalities. Subjects were divided into an improvement group and a non-improvement group based on the difference before and after oral administration of an herbal medicine. Efficacy models of triglyceride level, high-density lipoprotein (HDL) cholesterol level, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were built using a least absolute shrinkage and selection operator (LASSO) based on variables extracted from face shape, face colors, body circumference, questionnaire, voice, and tongue color. In predicting efficacy for four metabolic risk factors, the efficacy model of HDL cholesterol level showed the best the area under the receiver operating characteristic curve (AUC) value among the four models (AUC = 0.785 (confidence interval = 0.693, 0.877)). The AUC value of the efficacy model of triglyceride level was 0.659 (0.551, 0.768). Efficacy models of DBP and SBP showed AUC values of 0.665 (0.551, 0.78) and 0.54 (0.385, 0.694), respectively. The results may provide a clue to predict whether a drug will be effective for each subject with phenotypic information and to reduce the use of an ineffective drug or its side effects. [ABSTRACT FROM AUTHOR]

We have synthesized a thermally curable polymeric gate insulator (TFVOB-SPI) through the modification of soluble polyimide (SPI) using a 4-(1,2,2-trifluorovinyloxy)benzoyl (TFVOB) chloride. The thermal cross-linking of TFVOB-SPI was done and prepared the cross-linked TFVOB-SPI thin film having the perfluorocyclobutane (PFCB) structure. The PFCB structure was formed by the radical mediated thermal cycloaddition of trifluorovinyl ether of TFVOB. The cross-linked TFVOB-SPI showed excellent thermal stability up to 495 °C with only 5% weight loss and excellent chemical resistance to common organic solvents. The pentacene thin-film transistor (TFT) with the cross-linked TFVOB-SPI as a gate dielectric exhibited a field effect mobility of 0.28 cm2/Vs with almost no hysteresis during the TFT operation. [ABSTRACT FROM AUTHOR]

A new carbazole-containing hyperbranched conjugated poly(phenylene vinylene) (Hyper-PCPPV) was synthesized through the Wittig polycondensation polymerization. Hyper-PCPPV has good solubility in common organic solvents and showed excellent thermal stability up to 425 °C with less than 5% weight loss. The photophysical properties of Hyper-PCPPV were investigated and compared with a carbazole-containing linear conjugated poly(para-phenylene vinylene) (Linear-PCPPV). An absorption maximum of Hyper-PCPPV film was determined at 353 nm which was far blue shifted than that of Linear-PCPPV (403 nm). Hyper-PCPPV showed blue photoluminescence (PL) peak at 448 nm. In addition, Hyper-PCPPV exhibited almost no excimer or aggregate emission peaks even when the polymer film was annealed at 80 °C for 30 min in air condition. [ABSTRACT FROM AUTHOR]

Two 1,3-bis(thiophen-2-yl)−5,7-bis(2-ehtylhexyl)benzo-[1,2-c:4,5-c]-dithiophene-4,8-dione (BDD) based small molecules, SM1 and SM2 are designed and synthesized by incorporating benzodithiophene (BDT) central core, BDD dual accepting units and 3-ethyl rhodamine as endcap group with various number of BDT units. We systematically investigated the synthesis, optical and electrochemical properties, and photovoltaic characteristics of these donor materials. The number of BDT units have a significant influence on Jsc due to interconnected structure and results in a broader absorption on thin film. The inverted devices employed for both small molecules exhibited power conversion efficiencies of 0.41% for SM1 and 0.82% for SM2. [ABSTRACT FROM AUTHOR]

We have prepared a photo-crosslinkable, low-temperature processable, and soluble polyimide (SPI-Cinnamoyl: SPI-CM) gate insulator. Firstly, the soluble polyimide with hydroxyl group (SPI-Hydroxyl: SPI-OH) was synthesized through one-step condensation polymerization of monomers, 5-(2,5-dioxytetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOCDA) and 3,3'-dihydroxy-4,4'-diaminobiphenyl (HAB). And, then SPI-OH was further reacted with cinnamoyl chloride to make a photo-crosslinkable polyimide (SPI-CM). The thin film of photo-crosslinked SPI-CM (C-SPI-CM) exhibited a dielectric constant as 3.7 at 10 kHz, and leakage current density of <9.7 × 10−11 A/cm2. In addition, SPI-CM could be easily patterned by selective UV-light exposure. A pentacene thin-film transistor (TFT) with the photo-crosslinked SPI-CM as a gate dielectric showed a field effect mobility of 0.16 cm2/Vs. [ABSTRACT FROM AUTHOR]

We have synthesized a thermally curable polymeric gate insulator (TFVOB-PVP) through the modification of the well-known poly(4-vinylphenol) (PVP) polymer using a 4-(1,2,2-trifluorovinyloxy) benzoyl (TFVOB) chloride. The thermal cross-linking of TFVOB-PVP was conducted and produced the cross-linked TFVOB-PVP with the perfluorocyclobutane (PFCB) structure. The PFCB structure was formed by the radical mediated thermal cycloaddition of trifluorovinyl ether group of TFVOB. The cross-linked TFVOB-PVP showed good thermal stability up to 423°C with only 5% weight loss and excellent chemical resistance to common organic solvents. The pentacene thin-film transistor (TFT) with the cross-linked TFVOB-PVP as a gate dielectric exhibited a field effect mobility of 0.14 cm2/Vs with almost no hysteresis during the TFT operation. [ABSTRACT FROM AUTHOR]

A novel fluorene containing hyperbranched conjugated poly(phenylene vinylene) (Hyper-PFPPV) was obtained through the Wittig polycondensation polymerization. Hyper-PFPPV has good solubility in common organic solvents and showed good thermal stability up to 369°C with less than 5wt% weight loss. The photophysical properties of Hyper-PFPPV in solution and net solid film are inspected and compared with fluorene containing linear poly(1,4-phenylene vinylene) (PFPPV). An absorption maximum of Hyper-PFPPV film was determined at 385 nm which was far blue shifted than that of linear PFPPV film (425 nm). Hyper-PFPPV showed blue photoluminescence (PL) peak at 461 nm. In addition, Hyper-PFPPV film exhibited almost no long wavelength emission peaks even the film was annealed at 80°C for 1 hr in air condition. High PL efficiencies (Φsol= 0.78 and Φfilm= 0.75) and no aggregate or excimer emission of Hyper-PFPPV are due to the inhibition of intramolecular or intermolecular interaction by the introduction of the hyperbranched network into the fluorene containing poly(phenylene vinylene) backbone. [ABSTRACT FROM AUTHOR]

We report a new polyvinyl alcohol (PVA)-tetraethoxysilane (TEOS) hybrid layer to protect an organic thin-film transistor (OTFT). PVA/TEOS hybrid thin film was successfully fabricated through hydrolysis and condensation mechanism. The surface roughness of PVA/TEOS film was measured by atomic force miscroscophy (AFM) and it showed a good surface roughness with a root-mean-squae value of about 0.23 nm. Thermally crosslinked PVA with TEOS was successfully adaped as a solution processable passivation layer for pentacene TFT. In case of well known photo-crosslinked PVA/ammonium dichromater (ADC) passivation, extremely large initial performance drop (almost 52% mobility drop) was observed after passivation. PVA/TEOS hybrid passiavtion, however, no significant initial performance drop was found after passivation process. In addition, pentacene TFT with PVA/TEOS passivation layer exhibited very stable TFT operation with almost no field mobility drop or threshold voltage shift up to 980 h. [ABSTRACT FROM AUTHOR]

Two novel thieno[3,4-b]pyrazine-based copolymers of the donor-acceptor type, poly[4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b’]dithiophene-alt-5,7-(2,3-bis-(4-octyl-oxy-phenyl)-thieno[3,4-b]pyrazine)] (P1) and poly[4,8-bis(5-((2-ethylhexylthiophene)-2-yl))benzo[1,2-b:4,5-b’]dithiophene-alt-5,7-(2,3-bis-(4-octyloxy-phenyl)-thieno[3,4-b]pyrazine)] (P2), designed and synthesized by Stille polymerization for use in polymer solar cells. The synthesis, thermal stability, as well as the optical and photovoltaic properties of these polymers are systematically investigated. The polymers were thermally stable up to 290°C, and readily soluble in common organic solvent. Conventional polymer solar cells (PSCs) with the configuration ITO/PEDOT:PSS/polymer:PC71BM/Ca/Al are fabricated. Under optimized conditions, the polymers display power conversion efficiencies (PCEs) for the PSCs in the range 0.28–1.46% under AM 1.5 illumination. Among the studied thienopyrazine-based copolymers, P2 displays a PCE of 1.46% with a short circuit current of 7.61 mA/cm2, an open circuit voltage of 0.43 V, and a fill factor of 0.45 under AM 1.5 illumination. [ABSTRACT FROM AUTHOR]

We report a new crosslinked polyvinyl alcohol (PVA) layer to protect organic thin-film transistors (OTFTs) using the glutaraldehyde (GA) as a crosslinking agent. After thermal crosslinking reaction of PVA with GA, the water contact angle was increased from 9.8° to 55.1° as more hydrophobic state. This clearly means that hydroxyl group of PVA surface was disappeared by the crosslinking reaction. Thermally crosslinked PVA/GA was successfully adapted as solution processable passivation layer for pentacene TFT. In case of well known photo-crosslinked PVA/ammonium dichromate (ADC) passivation, extremely large initial performance drop (almost 52% mobility drop) was observed after passivation. PVA/GA passivation, however, only 3.8% initial mobility drop was found after passivation process. In addition, pentacene TFT with PVA/GA passivation layer exhibited very stable TFT operation with almost no field effect mobility drop or threshold voltage shift up to 1100 h. [ABSTRACT FROM PUBLISHER]

A set of novel conjugated polyfluorene co- polymers, poly[(9,9′-didecylfluorene-2,7-diyl)- co-(4,7′-di-2-thienyl- 2′,1′,3′-benzothiadiazole-5,5-diyl)- co-(pyrene-1,6-diyl)], are synthesized via Pd(II)-mediated polymerization from 2,7-bis(4′,4′,5′, 5′-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9′-di- n-decylfluorene, 4, 7-di(2-bromothien-5-yl)-2,1,3-benzothiadiazole, and 1,6-dibromopyrene with a variety of monomer molar ratios. The field-effect carrier mobilities and optical, electrochemical, and photovoltaic properties of the copolymers are systematically investigated. The hole mobilities of the copolymers are found to be in the range 7.0 × 10−5 − 8.0 × 10−4 cm2 V−1 s−1 and the on/off ratios were 8 × 103 − 7 × 104. Conventional polymer solar cells (PSCs) with the configuration ITO/PEDOT:PSS/polymer:PC71BM/LiF/Al are fabricated. Under optimized conditions, the polymers display power conversion efficiencies (PCEs) for the PSCs in the range 1.99-3.37% under AM 1.5 illumination (100 mW cm−2). Among the four copolymers, P2, containing a 2.5 mol % pyrene component incorporated into poly[9,9′-didecylfluorene-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PFDTBT) displays a PCE of 3.37% with a short circuit current of 9.15 mA cm−2, an open circuit voltage of 0.86 V, and a fill factor of 0.43, under AM 1.5 illumination (100 mW cm−2). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

A novel hyperbranched conjugated poly(fluorene) (Hyper-PDHF) was obtained through the Suzuki coupling polymerization. Hyper-PDHF has good solubility in common organic solvents and showed good thermal stability up to 428°C with less than 5 wt% weight loss. The photophysical properties of Hyper-PDHF in solution and net solid film are inspected and compared with poly(di-n-hexylfluorene) (PDHF) having linear structure. An absorption maximum of Hyper-PDHF film was determined at 334 nm which was far blue shifted than that of linear PDHF film (381 nm). Hyper-PDHF showed absolute blue photoluminescence (PL) peak at 418 nm with 394 and 444 nm as shoulder peaks. Hyper-PDHF showed also high fluorescence quantum yield as about Φsol = 0.81. In addition, Hyper-PDHF film exhibited almost no longer wavelength emission peaks even the film was annealed at 80°C for 1 hr with illuminating UV (365 nm) in air condition. The high PL efficiency and no aggregate or excimer emission of Hyper-PDHF results from the inhibition of intramolecular or intermolecular interaction by the introduction of the hyperbranched network into the poly(fluorene) backbone. [ABSTRACT FROM PUBLISHER]

Using conductive functional ink comprising Cu/CuO core–shell nanoparticles, we present the printed Cu source/drain electrode surrounded by a CuO hole injection layer for organic thin-film transistors. The inherent CuO hole injection layer facilitates the transistor with electrical performance comparable to that of a transistor based on a vacuum deposited Au electrode, without additional physical or chemical treatments for obtaining an energetically compatible interface between the electrode and p-type organic semiconductor. [ABSTRACT FROM AUTHOR]

We have synthesised a series of new reactive mesogens with photopolymerisable di-acrylates and their corresponding non-reactive analogues based on the π-conjugated aromatic core, fluorene (F)-di-[thiophene (T)-benzene (B)], using the Stille and Suzuki coupling reaction. The effect of lateral alkyl chains on the 9-position of the central fluorene moiety as well as α, ω- side alkyl chains attached to the π-conjugated aromatic core on the mesomorphism was investigated by utilising differential scanning calorimetry (DSC) and polarising optical microscopy (POM). A wide angle X-ray scattering (WAXS) study at the various temperatures was also carried out to reveal phase structures. Photopolymerisable di-acrylates connected directly to the rigid aromatic core showed higher phase transition temperatures, probably due to the induced dipole moment in comparison with those of a non-reactive methyl-ether counterpart. [ABSTRACT FROM AUTHOR]

Abstract: We report the results of a systematic investigation of the electrical and physical modifications to pentacene organic thin-film transistors (OTFT) that result from postfabrication thermal annealing. The thermally induced electrical modifications of the performance of the pentacene OTFTs were explored, and the morphology and structure of the pentacene films were investigated using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. We found that postfabrication thermal annealing at 50°C significantly improved the mobility, from 0.19 to 0.36cm2/Vs, and increased the on/off ratio to almost twice that of the non-annealed device. We also found that annealing increased the pentacene grain size and enhanced the 001 peak intensity in the XRD pattern, indicating greater molecular ordering. At postfabrication thermal annealing temperatures of 70°C and above, the pentacene films lose their crystallinity and the OTFT performance is decreased. [Copyright &y& Elsevier]

The effect of ion concentration, neutralization level and counterions in ionomers was systematically studied to obtain the optimal electroluminescent (EL) characteristics in polymer light-emitting diodes using poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV) for the emissive layer and sulfonated polystyrene (SPS) ionomers for the electron-injecting layer. The optimum ion concentration of NaSPS was determined to be at 6.7 mol %. Ionomers with a higher neutralization level make the EL device more efficient, with the highest efficiency being at 200% overneutralization. The ionomer with a smaller metal counter ion greatly enhances the efficiency of EL devices with the indium–tin–oxide/MEH-PPV/LiSPS/Al device having the highest EL quantum efficiency, 1.18% photons/electron. The dominant factor in enhancing the luminance is the number of ionic dipoles near the cathode irrespective of the type of metal counterions, while the hole blocking mostly depends on the restriction of chain segmental motion in ionomers. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]