Indolocarbazole-Based Photo-Crosslinkable Hole-Transporting Layer for Efficient Solution-Processed Organic Light-Emitting Diodes.

We designed and synthesized a new indolocarbazole-based polymer, poly(N,N-diphenyl(5,11-dihexylindolo[3,2,1-jk]carbazol-2-yl)amine) (PICA), for solution-processed organic light-emitting diodes (OLEDs). The highest occupied and lowest unoccupied molecular orbital energy levels of this polymer, -5.25 and -2.

Thermal Management Enables Stable Perovskite Nanocrystal Light-Emitting Diodes with Novel Hole Transport Material.

The severely insufficient operational lifetime of perovskite light-emitting diodes (LEDs) is incompatible with the rapidly increasing external quantum efficiency, even as it approaches the theoretical limit, thereby significantly impeding the commercialization of perovskite LEDs. In addition, Joule heating induces ion migration and surface defects, degrades the photoluminescence quantum yield and other optoelectronic properties of perovskite films, and induces the crystallization of charge transport layers with low glass transition temperatures, resulting in LED degradation under continuous operation. Here, a novel thermally crosslinked hole transport material, poly(FCA -co-BFCA -co-VFCA ) (poly-FBV), with temperature-dependent hole mobility is designed, which is advantageous for balancing the charge injection of the LEDs and limiting the generation of Joule heating.

Highly Efficient Deep-Blue Phosphorescent OLEDs Based on a Trimethylsilyl-Substituted Tetradentate Pt(II) Complex.

Compared to Ir(III) complexes with octahedral geometries, Pt(II) complexes with square planar geometries show superior optical properties because their flat shapes lead to an orientation that enhances the outcoupling of organic light-emitting diodes (OLEDs). However, the flat shapes of Pt(II) complexes typically induce a bathochromic shift, limiting their application in high-performance deep-blue phosphorescent OLEDs with high color purity. In this study, bulky trimethylsilyl (TMS)-substituted blue phosphorescent Pt(II) complex (PtON7-TMS) is successfully synthesized to improve color purity.

Dinuclear Pt(II) Complexes with Red and NIR Emission Governed by Ligand Control of the Intramolecular Pt-Pt Distance.

Red and near-infrared (NIR) phosphorescent double-decker dinuclear Pt(II) complexes were synthesized, and their structural and spectroscopic properties were characterized. The Pt(II) complexes, which are composed of achiral ligands and are themselves chiral, were shown to exist as racemic mixtures using single-crystal X-ray crystallography. The Pt(II) complexes have different intramolecular Pt-Pt distances that are governed by the electronic characteristics of the component C^N ligands.

Novel Conjugated Polymers Containing 3-(2-Octyldodecyl)thieno[3,2-]thiophene as a π-Bridge for Organic Photovoltaic Applications.

3-(2-Octyldodecyl)thieno[3,2-]thiophen was successfully synthesized as a new π-bridge with a long branched side alkyl chain. Two donor-π-bridge-acceptor type copolymers were designed and synthesized by combining this π-bridge structure, a fluorinated benzothiadiazole acceptor unit, and a thiophene or thienothiophene donor unit, ( or respectively) through Stille polymerization. Inverted OPV devices with a structure of ITO/ZnO/polymer:PCBM/MoO/Ag were fabricated by spin-coating in ambient atmosphere or N within a glovebox to evaluate the photovoltaic performance of the synthesized polymers (effective active area: 0.

Thermally Cross-Linkable Styrene-Based Host Materials for Solution-Processed Organic Light-Emitting Diodes.

Thermally cross-linkable host materials, DV-TPACZ, DV-TPADBCZ, and TV-TPBI, were designed and synthesized for solution-processed organic light-emitting diodes (OLEDs). The synthesized styrene-functionalized host materials were thermally cross-linked by curing at 150-200 °C without using a polymerization initiator. Excellent solvent resistance was observed for all cured host films.

Synthesis of Novel Polyacrylates Containing Cyclotetrasiloxane for Fouling-Release Coating Applications.

An acrylate monomer containing cyclotetrasiloxane (CTS) were designed and synthesized for anti-fouling coating applications. New acryl-based copolymers consisting of styrene and CTS, poly(styrene--CTS)s, were synthesized by changing molar ratios via free radical polymerization. The properties of poly(styrene--CTS)s were compared with those of poly(styrene) (PS) as a reference.

Blue Phosphorescent Bipyridine-Based Iridium(III) Complex for Vacuum-Deposited Organic Light-Emitting Diodes.

We have synthesized and characterized a blue phosphorescent iridium(III) complex (dfpypy)2Ir(tftamp), which contains 2',6'-difluoro-2,3'-bipyridine (dfpypy) as the main ligand and 4-methyl-2-(3'-trifluoromethyl-1'H-1',2',4'-triazol-5'-yl)pyridine (tftamp) as the ancillary ligand. The photophysical, electrochemical, and electroluminescent (EL) properties of (dfpypy)2Ir(tftamp) were investigated. Vacuum-deposited blue and white organic light-emitting diodes (OLEDs) were fabricated using (dfpypy)2Ir(tftamp) in 1,3-bis(carbazol-9-yl)benzene (mCP) as the emitting layer.

Synthesis and Properties of Fluorinated Styrene Copolymers as Antibiofouling Coatings.

A series of polystyrene (PS) copolymers containing 2,3,4,5,6-pentafluorostyrene units with different monomer ratios were prepared for antifouling applications. PS, poly(styrene-co-pentafluorostyrene) (poly(S-co-FS)), and poly(pentafluorostyrene) (PFS) were synthesized by free-radical polymerization and characterized by 1H NMR, Fourier-transform infrared spectroscopy, and gel permeation chromatography. The surface energy of the polymer films decreased with increasing content of fluorinated styrene.

Polystyrene-block-Poly(ionic liquid) Copolymers as Work Function Modifiers in Inverted Organic Photovoltaic Cells.

Interfacial layers play a critical role in building up the Ohmic contact between electrodes and functional layers in organic photovoltaic (OPV) solar cells. These layers are based on either inorganic oxides (ZnO and TiO) or water-soluble organic polymers such as poly[(9,9-dioctyl-2,7-fluorene)-alt-(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)] and polyethylenimine ethoxylated (PEIE). In this work, we have developed a series of novel poly(ionic liquid) nonconjugated block copolymers for improving the performance of inverted OPV cells by using them as work function modifiers of the indium tin oxide (ITO) cathode.

Synthesis of a Zr-Based Metal-Organic Framework with Spirobifluorenetetrabenzoic Acid for the Effective Removal of Nerve Agent Simulants.

A new microporous Zr(IV)-based metal-organic framework (MOF) containing 4,4',4″,4‴-(9,9'-spirobi[fluorene]-2,2',7,7'-tetrayl)tetrabenzoic acid (Spirof-MOF) was synthesized, characterized, and size-controlled for the adsorption and decomposition of a nerve agent simulant, dimethyl 4-nitrophenylphosphate (DMNP). Spirof-MOF showed a hydrolysis half-life (t) of 7.5 min to DMNP, which was confirmed by using in situ P NMR spectroscopy.

Layer-by-Layer Assembled Films of Perylene Diimide- and Squaraine-Containing Metal-Organic Framework-like Materials: Solar Energy Capture and Directional Energy Transfer.

We demonstrate that thin films of metal-organic framework (MOF)-like materials, containing two perylenediimides (PDICl4, PDIOPh2) and a squaraine dye (S1), can be fabricated by layer-by-layer assembly (LbL). Interestingly, these LbL films absorb across the visible light region (400-750 nm) and facilitate directional energy transfer. Due to the high spectral overlap and oriented transition dipole moments of the donor (PDICl4 and PDIOPh2) and acceptor (S1) components, directional long-range energy transfer from the bluest to reddest absorber was successfully demonstrated in the multicomponent MOF-like films.

Synthesis of nanocrystals of Zr-based metal-organic frameworks with csq-net: significant enhancement in the degradation of a nerve agent simulant.

The synthesis of nano-sized particles of NU-1000 (length from 75 nm to 1200 nm) and PCN-222/MOF-545 (length from 350 nm to 900 nm) is reported. The catalytic hydrolysis of methyl paraoxon was investigated as a function of NU-1000 crystallite size and a significant enhancement in the rate was observed for the nano-sized crystals compared to microcrystals.

Rational design, synthesis, and characterization of deep blue phosphorescent Ir(III) complexes containing (4'-substituted-2'-pyridyl)-1,2,4-triazole ancillary ligands.

On the basis of the results of frontier orbital considerations, 4-substituted-2'-pyridyltriazoles were designed to serve as ancillary ligands in 2-phenylpyridine main ligand containing heteroleptic iridium(III) complexes that display deep blue phosphorescence emission. The iridium(III) complexes, Ir1-Ir7, prepared using the new ancillary ligands, were found to display structured, highly quantum efficient (Φp = 0.20-0.

Photoaddition reactions of acetylpyridines with silyl ketene acetals: SET vs [2 + 2]-cycloaddition pathways.

Photoaddition reactions of silyl ketene acetals with 2-, 3- and 4-acetylpyridine have been explored. The results show that the acetylpyridines react with an electron rich, dimethyl-substituted silyl ketene acetal via a pathway in which excited state single electron transfer (SET) takes place to produce β-hydroxyesters in high yields. In contrast, photochemical reactions of the acetylpyridines with an electron deficient, nonmethyl-substituted silyl ketene acetal generate oxetanes as major products, which arise via a route involving excited state [2 + 2]-cycloaddition.

Exploration of photochemical reactions of N-trimethylsilylmethyl-substituted uracil, pyridone, and pyrrolidone derivatives.

Photochemical reactions of N-trimethylsilylmethyl-substituted uracil, pyridone and pyrrolidone derivatives were carried out to determine if silicone containing substituents have an impact on excited state reaction profiles. The results show that ultraviolet irradiation of N-trimethylsilylmethyl substituted uracils in the presence of substituted alkenes leads to efficient formation of both dimeric and cross [2+2]-cycloaddition products. Qualitatively similar observations were made in a study of the photochemistry of N-trimethylsilylmethyl-2-pyridone.

Regioselectivity of enzymatic and photochemical single electron transfer promoted carbon-carbon bond fragmentation reactions of tetrameric lignin model compounds.

New types of tetrameric lignin model compounds, which contain the common β-O-4 and β-1 structural subunits found in natural lignins, have been prepared and carbon-carbon bond fragmentation reactions of their cation radicals, formed by photochemical (9,10-dicyanoanthracene) and enzymatic (lignin peroxidase) SET-promoted methods, have been explored. The results show that cation radical intermediates generated from the tetrameric model compounds undergo highly regioselective C-C bond cleavage in their β-1 subunits. The outcomes of these processes suggest that, independent of positive charge and odd-electron distributions, cation radicals of lignins formed by SET to excited states of sensitizers or heme-iron centers in enzymes degrade selectively through bond cleavage reactions in β-1 vs β-O-4 moieties.

Nature and kinetic analysis of carbon-carbon bond fragmentation reactions of cation radicals derived from SET-oxidation of lignin model compounds.

Features of the oxidative cleavage reactions of diastereomers of dimeric lignin model compounds, which are models of the major types of structural units found in the lignin backbone, were examined. Cation radicals of these substances were generated by using SET-sensitized photochemical and Ce(IV) and lignin peroxidase promoted oxidative processes, and the nature and kinetics of their C-C bond cleavage reactions were determined. The results show that significant differences exist between the rates of cation radical C1-C2 bond cleavage reactions of 1,2-diaryl-(β-1) and 1-aryl-2-aryloxy-(β-O-4) propan-1,3-diol structural units found in lignins.

Photoaddition reactions of 1,2-diketones with silyl ketene acetals. formation of beta-hydroxy-gamma-ketoesters.

Photochemical reactions taking place between 1,2-diketones and silyl ketene acetals and their excited state reaction mechanisms have been explored. Irradiation of benzene, acetone, or acetonitrile solutions containing 1,2-diketones and silyl ketene acetals is observed to promote formation of 1,4-dioxenes, resulting from [4 + 2]-cycloaddition, oxetanes, arising by Paterno-Buchi processes, and beta-hydroxy-gamma-ketoesters, generated by SET-promoted Claisen-type condensation. These competitive pathways leading from the excited states of the 1,2-diketones to these products are influenced by solvent polarity and the nature of the silyl ketene acetal and 1,2-diketone.

Beneficial effects of simultaneous treatment with 15-deoxyspergualin and monoclonal antibodies to CD45RB and CD154 on murine islet transplantation recipients.

Background: Treatment of transplant recipients with either 15-deoxyspergualin (DSG) or monoclonal antibodies (mAbs) to T-cell proteins CD45RB and CD154 (a two-signal blockade) has been shown to prolong islet graft survival. Therefore, we investigated the combined effect of DSG, anti-CD45RB, and anti-CD154 in murine islet model.

Methods: Chemically induced diabetic C57BL/6 mice underwent allografting with islets from BALB/c mice or xenografting with rat islets.