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The circularly polarized organic light-emitting diodes (CP-OLEDs) demonstrate promising application in 3D display due to the direct generation of circularly polarized electroluminescence (CPEL). But the chiral luminescence materials face challenges as intricated synthetic route, enantiomeric separation, etc. Herein, fresh CP-OLEDs are designed based on chiral hole transport material instead of chiral emitters. A pair of hole transport enantiomers (R/S-NPACZ) exhibit intense dissymmetry factors (|g PL |) about 5.0 × 10 -3 . With R/S-NPACZ as hole transport layers, CP-OLEDs are fabricated employing six achiral phosphorescence and thermally activated delayed fluorescence (TADF) materials with different wavelengths, in consistence with the generated CPEL spectra. The CP-OLEDs based on achiral red, green, and blue iridium(III) complexes exhibit external quantum efficiencies (EQEs) of 14.9%, 30.7%, and 14.1% with |g EL | factors of 8.8 × 10 -4 , 2.3 × 10 -3 , and 2.0 × 10 -3 , respectively. Moreover, the devices using achiral blue, blueish-green, and green TADF materials display EQEs of 24.1%, 17.9%, and 25.4% with |g EL | factors of 1.0 × 10 -3 , 3.6 × 10 -3 , and 2.2 × 10 -3 , respectively. As far as known, it is the first example of CP-OLEDs based on chiral hole transport materials, which act as the organic circularly polarizers and have potential to generate CPEL from achiral luminescence materials., (© 2024 Wiley‐VCH GmbH.)

Chiral boron/nitrogen doped multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters are promising for highly efficient and color-pure circularly polarized organic light-emitting diodes (CP-OLEDs). Herein, we report two pairs of MR-TADF materials (Czp-tBuCzB, Czp-POAB) based on planar chiral paracyclophane with photoluminescence quantum yields of up to 98 %. The enantiomers showed symmetric circularly polarized photoluminescence spectra with dissymmetry factors |g PL | of up to 1.6×10 -3 in doped films. Meanwhile, the sky-blue CP-OLEDs with (R/S)-Czp-tBuCzB showed an external quantum efficiency of 32.1 % with the narrowest full-width at half-maximum of 24 nm among the reported CP-OLEDs, while the devices with (R/S)-Czp-POAB displayed the first nearly pure green CP electroluminescence with |g EL | factors at the 10 -3 level. These results demonstrate the incorporation of planar chirality into MR-TADF emitter is a reliable strategy for constructing of efficient CP-OLEDs., (© 2022 Wiley-VCH GmbH.)

Herein, we report the structures of chiral-at-cage carborane derivatives bearing carbazole chromophores that emit circularly polarized luminescence (CPL) and aggregation-induced electrochemiluminescence (AIECL). By adjusting the substituent positions on the carborane derivatives, two chiral luminescent molecules, Cb1 and Cb2, with different properties were obtained. The photoluminescence dissymmetry factors |g PL | of both (R/S)-Cb1 and (R/S)-Cb2 enantiomers in neat films were as high as 6.24×10 -3 and 7.38×10 -3 , respectively. Cb1 showed a deep blue emission peak at 434 nm in n-pentane. Interestingly, distinct fluorescence and CPL spectra were observed in solvents of different polarities due to the twisted intramolecular charge transfer effect, suggesting its potential use in solvent recognition. Meanwhile, Cb2 exhibited good AIECL property, excellent ECL stability and could be used for determining dopamine concentrations, suggesting its potential applications in biology and diagnosis., (© 2022 Wiley-VCH GmbH.)

The realization of luminescent materials with narrowband and circularly polarized luminescence (CPL) is of great significance for the development of future optical and photonic devices. Herein, through a steric-hindrance-assisted dual-core strategy, two pairs of chiral dual-core multiple resonance thermally activated delayed fluorescence (MR-TADF) materials (R/S-DOBN and R/S-DOBNT) are directly constructed by the bonding of two organoboron MR-TADF monocores (SOBN and SOBNT) with carbazole/3,6-di-tert-butyl-9H-carbazole and phenol derivative as donors, realizing obvious CPL and narrowband emissions. Furthermore, the dual-core effect in the prepared R/S-DOBN and R/S-DOBNT increases the transition oscillator strength two times more than that of a monocore structure, while maintaining the ultrapure blue emissions peaking at 453 and 459 nm with a narrower full-width at half-maximum of 21 nm through reorganization energy reduction. The circularly polarized organic light-emitting diodes based on the enantiomers exhibit ultrapure blue emission with Commission Internationale de L'Eclairage (CIE) coordinates of (0.14, 0.10) and (0.13, 0.12), high maximum external quantum efficiencies of 23.9% and 25.6%, and obvious circularly polarized electroluminescence with dissymmetry factors (|g EL |) ≈ 10 -3 ., (© 2022 Wiley-VCH GmbH.)

Click chemistry focuses on the development of highly selective reactions using simple precursors for the exquisite synthesis of molecules. Undisputedly, the Cu I -catalyzed azide-alkyne cycloaddition (CuAAC) is one of the most valuable examples of click chemistry, but it suffers from some limitations as it requires additional reducing agents and ligands as well as cytotoxic copper. Here, we demonstrate a novel strategy for the azide-alkyne cycloaddition reaction that involves a photoredox electron-transfer radical mechanism instead of the traditional metal-catalyzed coordination process. This newly developed photocatalyzed azide-alkyne cycloaddition reaction can be performed under mild conditions at room temperature in the presence of air and visible light and shows good functional group tolerance, excellent atom economy, high yields of up to 99 %, and absolute regioselectivity, affording a variety of 1,4-disubstituted 1,2,3-triazole derivatives, including bioactive molecules and pharmaceuticals. The use of a recyclable photocatalyst, solar energy, and water as solvent makes this photocatalytic system sustainable and environmentally friendly. Moreover, the azide-alkyne cycloaddition reaction could be photocatalyzed in the presence of a metal-free catalyst with excellent regioselectivity, which represents an important development for click chemistry and should find versatile applications in organic synthesis, chemical biology, and materials science., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)