Synthesis of Homo- and Copoly(arylene bicarbazole)s via Nucleophilic Substitution Polycondensation Reactions of NH Groups with Activated Dihalides

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

In this work we showcase the emitter DICzTRZ in which we employed a twin-emitter design of our previously reported material, ICzTRZ. This new system presented a red-shifted emission at 488 nm compared to that of ICzTRZ at 475 nm and showed a comparable photoluminescence quantum yield of 57.1% in a 20 wt % CzSi film versus 63.3% for ICzTRZ. The emitter was then incorporated within a solution-processed organic light-emitting diode that showed a maximum external quantum efficiency of 8.4%, with Commission Internationale de l'Éclairage coordinate of (0.22, 0.47), at 1 mA cm-2.

Carbazole-Fused Polycyclic Aromatics Enabled by Regioselective Scholl Reactions

The synthesis of new carbazole-fused polycyclic aromatics with interesting geometry and useful properties was explored using Scholl reactions. As found from the Scholl reactions of substrates having two carbazole units linked at different positions through o-phenylene, oxidative coupling of carbazole units occurred in a regioselective manner with new carbon-carbon bonds preferably formed at C3 and C4 in N-alkyl carbazoles. A new N-containing aromatic bowl was characterized by single-crystal X-ray crystallography, and new p-type organic semiconductors exhibited field effect mobility of up to 0.070 cm²  V^-1  s^-1 in solution-processed thin-film transistors.

Synthesis and Chiroptical Properties of Chiral Carbazole-Based BODIPYs

A series of carbazole-based boron dipyrromethenes (BODIPYs) 2 a-g bearing binaphthyl units have been synthesized by the Et₂ AlCl-mediated reaction of the corresponding BODIPY difluorides 1 a-g with 1,1'-binaphthalene-2,2'-diol. Substituents such as halogen, nitrile, and amino groups were tolerated under the reaction conditions, and the reaction of the phenylethynyl-substituted 1 h gave (R,R)-3 h bearing two binaphthyl units. The chiroptical properties of these dyes with different substituents were investigated by UV/Vis, CD, fluorescence, and circularly polarized luminescence (CPL) spectroscopy. The CD spectra showed Cotton effects in the absorption region of the BODIPY moieties. In addition, they showed CPL both in solution and in the solid state. Interestingly, several dyes recorded higher g_lum values in the solid state, probably due to intermolecular interactions. Because (R,R)-3 h recorded relatively low g_lum values, the diastereomer (R,S)-3 h was prepared. The (R,S) diastereomer showed intense CPL, which suggests a synergetic effect of the two binaphthyl groups. Finally, chiral carbazole-based BODIPY dimers have been synthesized for the first time and their chiroptical properties were investigated. They showed redshifted fluorescence and CPL, which reached the near-IR (NIR) region in the solid state.

3,3'-Bicarbazole-Based Host Molecules for Solution-Processed Phosphorescent OLEDs

Solution-processed organic light-emitting diodes (OLEDs) are attractive due to their low-cost, large area displays, and lighting features. Small molecules as well as polymers can be used as host materials within the solution-processed emitting layer. Herein, we report two 3,3′-bicarbazole-based host small molecules, which possess a structural isomer relationship. 9,9′-Di-4-n-butylphenyl-9H,9′H-3,3′-bicarbazole (BCz-nBuPh) and 9,9′-di-4-t-butylphenyl-9H,9′H-3,3′-bicarbazole (BCz-tBuPh) exhibited similar optical properties within solutions but different photoluminescence within films. A solution-processed green phosphorescent OLED with the BCz-tBuPh host exhibited a high maximum current efficiency and power efficiency of 43.1 cd/A and 40.0 lm/W, respectively, compared to the device with the BCz-nBuPh host.

High efficiency solution-processed blue electrophosphorescent device with a bipolar host material based on diphenylphosphine oxide unit

A new bipolar host material BCz-BPO for solution-processed blue phosphorescent OLED was designed and synthesized. The device showed a maximum luminance efficiency of 30.1 cd A⁻¹, which was about three times higher compared with that of BCz-PO.

Direct synthesis of triphenylamine-containing polyarylsulfones from commercially available aniline

A novel triphenylamine-containing polyarylsulfone (PAS-TPA) was synthesized from commercially available aniline and 1,1′-sulfonylbis(4-fluorobenzene) via two-step N–C coupling reaction under nucleophilic substitution polycondensation condition. Subsequently, a new series of polysulfones with different TPA contents (PSU-TPAs) was developed by the same method. Both PAS-TPA and PSU-TPAs not only exhibited good thermal stability and solubility but also exhibited intense ultraviolet absorption and fluorescence and high fluorescence quantum yield (approximately 16–42%). Their ideal highest occupied molecular orbital level (approximately −5.5 to −5.6) indicated the potential application of these polymers in organic photoelectronic fields.

Synthesis and characterization of poly(arylene ether ketone)s with 3,6-diphenyl-9H-carbazole pendants using C–N coupling reaction

3,6-Diphenyl-9 H-carbazole pendants are grafted herein to poly(arylene ether ketone)s (PAEKs) via the Ullmann C–N coupling reaction. To the best of our knowledge, this is the first time that PAEKs containing a carbazole pendant (Cz) have been synthesized through the Ullmann C–N coupling reaction. The high molecular weights of PAEK-Cz (PAEKs with 3,6-diphenyl-9 H-carbazole pendants) are inherited from their precursors, owing to the high reactivity of their monomers. The obtained PAEK-Cz- x polymers exhibit good solubility in most common organic solvents and excellent thermal stabilities, with the 5% weight loss temperatures for all products being above 598°C under a nitrogen atmosphere. The glass transition temperatures are all above 199°C and can be controlled by adjusting the feed ratio of monomers. The polymer membranes obtained by the casting method are tough and thus have strong potential for practical applications.

Synthesis and characterization of novel high-performance polyarylsulfones with 4-(carbazol-9-yl) triphenylamine moieties

A novel homopolyarylsulfone with 4-(carbazol-9-yl) triphenylamine moieties was synthesized successfully through N–C coupling reactions under similar conditions to the synthesis of polyarylsulfones (PSU). By using this simple method and adjusting the feed ratio between 9-(4-aminobenzene) carbazole (NH2–Ar–Cz) and bisphenol A, a series of high-performance copolymers with high molecular weight, good film-reforming ability, great thermal stability, and excellent photoelectric characteristics were also prepared, which have good application potential in the field of organic optoelectronics.

3,3'-Bicarbazole-based host materials for high-efficiency blue phosphorescent OLEDs with extremely low driving voltage

Four types of functionalized 3,3'-bicarbazole derivatives are prepared and investigated as a host material for blue phosphorescent OLEDs. By using a 3,3'-bicarbazole derivative/FIrpic film as an emissive layer, high power efficiency of 46 lm W(-1) (45 cd A(-1), EQE 20%) with an extremely low driving voltage at 3.1 V is obtained at 100 cd m(-2).

Preparation of carboxylated/sulfonated poly(arylene ether ketone)s for proton exchange membranes

Derived from a hydroquinone monomer, a series of poly(arylene ether ketone)s containing ethyl benzoate pendants were first prepared as starting materials via aromatic nucleophilic substitution polycondensations. Sulfonated analogues could be obtained by simply stirring the obtained polymers in 95–98% sulfuric acid at room temperature. Following this, poly(arylene ether ketone)s bearing both carboxyl and sulfonic acid groups were prepared through a hydrolysis reaction of the ester groups on the above sulfonated polymers. The properties, including thermal, oxidative and dimensional stability, water absorption, mechanical properties, proton conductivity and methanol crossover of both sulfonated and sulfonated/carboxylated polymers were well investigated. It was found that some membranes exhibited good properties for proton exchange membranes.

Synthesis and Properties of Polymers Containing 2H-Benzimidazol-2-one Moieties: Polymerization via N-C Coupling Reactions

Novel homopolymers and copolymers containing 2H-benzimidazol-2-one units have been synthesized by N-C coupling reactions of 1H-benzo[d]imidazol-2(3H)-one and activated aromatic dihalides under conditions similar to those for the synthesis of poly(aryl ether)s and poly(benzimidazole sulfone)s. 1H-Benzo[d]imidazol-2(3H)-one behaved like a bisphenol in the polymerization reaction to afford, quantitatively, high molecular weight linear polymers with inherent viscosities (η_inh) ranging from 0.57 to 1.31 dL/g. The polymers were soluble in various organic solvents, and transparent, flexible, and creasable films were cast from its dichloromethane-solution. The homopolymer had a remarkably high glass transition temperature (T_g 348 °C) and good thermal stability. Only 30 mol % (8.9 wt %) of the 2H-benzimidazol-2-one unit for the copolymer with 4,4'-biphenol was required to raise the T_g of commercial poly(aryl ether), Radel R-5000 from 220 to 269 °C.