Polymer Hosts Containing Carbazole-Dibenzothiophene-Based Pendants for Application in High-Performance Solution-Processed TADF-OLEDs.

The film-forming capability of the host plays a crucial role in effectively forming a light-emitting layer through a solution process in organic light-emitting diodes (OLEDs). In this study, we synthesized two side-chain polymer hosts, and , consisting of carbazole and dibenzothiophene. The synthesis was carried out through radical polymerization using styrene-based host monomers.

Effect of intramolecular energy transfer in a dual-functional molecular dyad on the performance of solution-processed TADF OLEDs.

This paper introduces the design concept of a dual-functional molecular dyad tailored specifically for solution-processable organic light-emitting diodes (OLEDs). Cy-tmCPBN, characterized by an asymmetric molecular dyad structure, integrates a host unit (tmCP) and a multiple-resonance (MR) emitter (CzBN) a non-conjugated cyclohexane linker. Cy-tmCPBN exhibited efficient intramolecular energy transfers (EnTs) from tmCP to the CzBN unit, as confirmed by time-resolved fluorescence experiments.

Enantioselective S-Alkylation of Sulfenamides by Phase-Transfer Catalysis.

A general phase-transfer catalyst (PTC) mediated enantioselective alkylation of N-acylsulfenamides is reported. Essential to achieving high selectivity was the use of the triethylacetyl sulfenamide protecting group along with aqueous KOH as the base under biphasic aqueous conditions to enable the reaction to be performed at -40 °C. With these key parameters, enantiomeric ratios up to 97.

Precision-Engineered Medium-Sized Molecular Host and Emitter for Ensuring Consistent Performance in Solution-Processed Narrowband OLEDs.

In this study, two novel multiple resonance (MR) emitters, DtCzBN and Cy-DtCzBN, were designed based on the well-known BCzBN structure and synthesized for narrowband solution-processed organic light-emitting diodes (OLEDs). Cy-DtCzBN possesses a dimeric V-shaped structure formed by coupling two individual DtCzBN units via a nonconjugated cyclohexane linker. When compared with DtCzBN, Cy-DtCzBN, as a medium-sized molecule, was found to maintain the optical and photophysical properties of the corresponding monomeric unit, DtCzBN, but exhibits high thermal stability, excellent solubility, and good film-forming ability.

Novel π-Extended Indolocarbazole-Based Deep-Blue Fluorescent Emitter with Remarkably Narrow Bandwidth for Solution-Processed Organic Light-Emitting Diodes.

In solution-processed organic light-emitting diodes (OLEDs), achieving high color purity and efficiency is as important as that in vacuum processes. Emitters suitable for solution processing must have excellent solubility in organic solvents, high molecular weight, and compatibility with the host materials. In this study, we synthesized a deep-blue emitter that satisfies the above conditions by introducing a 1,4-bis(indolo[3,2,1-]carbazol-2-yl)benzene-based planar emitting core (DICz) structure and four 3,6-di--butyl-9-phenyl-9-carbazole (Cz) peripheral units, namely, 4Cz-DICz.

Catalyst-Controlled C-H Allylation and Annulation of 2-Aryl Quinazolinones with 2-Methylidene Cyclic Carbonate.

The site-selective modification of quinazolinone as a privileged bicyclic N-heterocycle is an attractive topic in medicinal chemistry and material science. We herein report the ruthenium(II)-catalyzed C-H allylation of 2-aryl quinazolinones with 2-methylidene cyclic carbonate. In addition, tandem C-H allylation and annulation are achieved under rhodium(III) catalysis, resulting in the formation of tetracyclic quinazolinones including a tertiary carbon center.

Rational Molecular Design Strategy for Host Materials in Thermally Activated Delayed Fluorescence-OLEDs Suitable for Solution Processing.

Herein, a novel core molecule for V-shaped host molecules was synthesized, wherein two carbazoles were directly linked to cyclohexane. and hosts were also successfully prepared for solution-processable thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs). The and molecules contained a cyclohexane linker directly linked to two small molecular hosts (mCP and mCBP), exhibiting twice the molecular weight while maintaining the basic properties of a single host molecule with improved film-forming ability and solubility in organic solvents.

Enhanced Efficiency and Stability of Novel Pseudo-ternary Polymer Solar Cells Enabled by a Conjugated Donor Block Copolymer.

The recent breakthrough in power conversion efficiencies (PCEs) of polymer solar cells (PSCs) that contain an active layer of a ternary system has achieved values of 18-19%; this has sparked interest for further research. However, this system has difficulties in optimizing the composition and controlling the interaction between the three active materials. In this study, we investigated the use of a donor (D)-donor (D) conjugated block copolymer (CBP), PM6--TT, to replace the physical blend of two donors.

Universal Polymeric Hole Transporting Material for Solution-Processable Green and Blue Thermally Activated Delayed Fluorescence OLEDs.

To obtain high-efficiency solution-processed organic light-emitting diodes (OLEDs), a hole transport material (HTM) capable of solution processing with excellent charge transport properties is required. In this study, a new vinyl polymer () containing hole-transporting 1,3-di(9-carbazol-9-yl)benzene (mCP) in the side chain was successfully synthesized via radical polymerization. showed good film-forming ability and thermal stability.

Customized Orthogonal Solvent System with Various Hole-Transporting Polymers for Highly Reproducible Solution-Processable Organic Light-Emitting Diodes.

Recently, various hosts and emitters for solution-processable thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) have been developed. However, a few studies have been conducted on hole transport materials (HTMs) with differentiated solubility characteristics for manufacturing multilayer OLEDs using a solution process. Here, three new hole transport (HT) styrene polymers, PICz, PPBCz, and PTPCz, were synthesized by radical polymerization.

Uniform Silver Nanowire Patterned Electrode on Robust PEN Substrate Using Poly(2-hydroxyethyl methacrylate) Underlayer.

Silver nanowire (AgNW) electrodes are among the most essential flexible transparent electrodes (FTEs) emerging as promising alternatives to brittle indium tin oxide (ITO) electrodes. The polymer comprising the plastic substrate to which the AgNWs are applied must also satisfy the mechanical requirements of the final device and withstand the device processing conditions. However, AgNW-based FTEs have some limitations, such as poor adhesion to coated plastic substrates, surface roughness, and difficulty in patterning.

KOBu-promoted C3-homocoupling of quinoxalinones through single electron transfer from an sp carbanion intermediate.

The C3-selective homodimerization of quinoxalinones is described. A C3-sp carbanion species generated through deprotonation of quinoxalinone using potassium -butoxide (KOBu) transfers an electron (single electron transfer mechanism) to a second quinoxalinone, affording a radical-anion intermediate. The radical scavenging and electron paramagnetic resonance (EPR) experiments support the plausible radical reaction pathway.

Patterned Sandwich-Type Silver Nanowire-Based Flexible Electrode by Photolithography.

Silver nanowires (AgNWs) are one of the important flexible electrode material candidates that can replace brittle indium tin oxide (ITO). In this work, we demonstrated novel patterned sandwich-type AgNW-based transparent electrodes easily prepared using the photolithography method for application in flexible devices. A cross-linked underlayer was introduced to increase the adhesion properties between a poly(ethylene terephthalate) substrate and AgNWs, and as a result, a uniform AgNW layer was easily deposited.

Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer.

This study demonstrated the use of a thermally crosslinked polyimide (PI) for the liquid crystal (LC) alignment layer of an LC display (LCD) cell. Polyamic acid was prepared using 4,4'-oxydianiline (ODA) and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The 6FDA-ODA-based polyimide (PI) prepared by the thermal cyclic dehydration of the polyamic acid (PAA) was soluble in various polar solvents.

Synthesis of spirosuccinimides annulative cyclization between -aryl indazolols and maleimides under rhodium(III) catalysis.

The rhodium(III)-catalyzed spiroannulation reaction between -aryl indazol-3-ols and maleimides is described herein. The developed method is showcased by the construction of spirosuccinimides using bioactive molecule-linked and chemical probe-linked maleimides. Combined mechanistic investigations including the determination of an isolable rhodacycle complex aided the elucidation of a plausible reaction mechanism.

Improved Stability of All-Polymer Solar Cells Using Crosslinkable Donor and Acceptor Polymers Bearing Vinyl Moieties in the Side-Chains.

Crosslinkable polymers have attracted tremendous attention in various fields of science and technology, owing to their potential utilization in applications requiring dimensional and morphological stability under thermal and mechanical stress. In this study, random terpolymers were successfully synthesized by introducing thiophene-based monomers bearing vinyl functional groups in the side-chain of the polymer donor () and polymer acceptor () structures. The physical properties of the blend films of and before and after thermal crosslinking were extensively investigated and compared to those of the homogeneous individual polymer films.

Nonhalogenated Solvent-Processed High-Performance Indoor Photovoltaics Made of New Conjugated Terpolymers with Optimized Monomer Compositions.

Conjugated random terpolymers, , , and were successfully synthesized from three different monomers. Fluorine-substituted benzotriazole (2F-BTA) was incorporated into 4,8-bis(4-chlorothiophen-2-yl)benzo[1,2-:4,5-']dithiophene (BDT-T-Cl) and a 1,3-bis(4-(2-ethylhexyl)thiophen-2-yl)-5,7-bis(2-alkyl)benzo[1,2-:4,5-']dithiophene-4,8-dione (BDD)-based alternating copolymer PM7 as a third monomeric unit. The solubility of the random terpolymers in nonhalogenated solvents increased with the number of 2F-BTA units in PM7.

Dynamics of Photoinduced Energy Transfer in Fully and Partially Conjugated Polymers Bearing π-Extended Donor and Acceptor Monomers.

The photophysical properties of donor ()-acceptor () polymers were studied by designing two types of polymers, and , with non-conjugated alkyl ( ) and π-conjugated ( ) linkers using π-extended donor and acceptor monomers that exhibit planar A-D-A structures. The non-conjugated alkyl linker provides structural flexibility to the polymers, while the π-conjugated linker retains the rigid structure of the polymers. Photoinduced energy transfer occurs from the large donor to acceptor units in both polymers.

C2-Selective C-H Methylation of Heterocyclic -Oxides with Sulfonium Ylides.

A redox-neutral C2-selective methylation of heterocyclic -oxides with sulfonium ylides is described herein. This report presents unprecedented findings for the utility of sulfonium ylides as the methylation source of -heterocycles beyond the Corey-Chaykovsky reaction. Intriguingly, pyrrolidine plays a significant role in minimizing the reductive C2-methylation process.

Environmentally Friendly Methylcellulose-Based Binders for Active and Passive Dust Control.

Particulate matter (PM) is an essential indicator to evaluate air pollution, threatening human health. Although PM control could be achieved by using a variety of polymeric materials, identifying effective and green materials remains elusive in dust control technology. Here, we have employed environmentally friendly cellulose modified by methyl side groups, such as methylcellulose (MC)-based polymers, and evaluated their PM reduction efficiency when utilized in active and passive dust control methods, such as dust suppressants and air filters, respectively.

C-H Methylation of Iminoamido Heterocycles with Sulfur Ylides*.

The direct methylation of N-heterocycles is an important transformation for the advancement of pharmaceuticals, agrochemicals, functional materials, and other chemical entities. Herein, the unprecedented C(sp )-H methylation of iminoamido heterocycles as nucleoside base analogues is described. Notably, trimethylsulfoxonium salt was employed as a methylating agent under aqueous conditions.

Significantly Improved Morphology and Efficiency of Nonhalogenated Solvent-Processed Solar Cells Derived from a Conjugated Donor-Acceptor Block Copolymer.

A highly crystalline conjugated donor (D)-acceptor (A) block copolymer (PBDT2T--N2200) that has good solubility in nonhalogenated solvents is successfully synthesized. PBDT2T--N2200 shows a broad complementary absorption behavior owing to a wide-band gap donor (PBDT2T) present as a D-block and a narrow-band gap acceptor (N2200) present as an A-block. Polymer solar cells (PSCs) with conjugated block copolymer (CBCP) are fabricated using a toluene solution and PSC created with an annealed film showing the highest power conversion efficiency of 6.

Deoxygenative Amination of Azine--oxides with Acyl Azides via [3 + 2] Cycloaddition.

A transition-metal-free deoxygenative C-H amination reaction of azine--oxides with acyl azides is described. The initial formation of an isocyanate from the starting acyl azide via a Curtius rearrangement can trigger a [3 + 2] dipolar cycloaddition of polar -oxide fragments to generate the aminated azine derivative. The applicability of this method is highlighted by the late-stage and sequential amination reactions of complex bioactive compounds, including quinidine and fasudil.

Site-Selective C-H Alkylation of Diazine -Oxides Enabled by Phosphonium Ylides.

The synthesis of alkylated diazine derivatives is important for their practical utilization as pharmaceuticals and for other purposes. Herein, we describe the metal-free site-selective C-H alkylation of diazine -oxides using phosphonium ylides that affords a variety of alkylated diazine derivatives with broad functional group tolerance. The utility of this method is showcased by the late-stage functionalization of a commercially available drug such as varenicline.

Ruthenium(II)-Catalyzed Site-Selective Hydroxymethylation of Indolines with Paraformaldehyde.

The facile synthesis of hydroxymethylated indole derivatives is crucial for their further development as pharmaceutical compounds and other synthetic purposes. Herein, we describe the ruthenium(II)-catalyzed hydroxymethylation of indolines and other N-heterocycles using paraformaldehyde as an abundant C1 feedstock. A wide substrate scope range and high levels of site selectivity as well as functional group tolerance were observed.