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Attaining phosphorescent materials with narrowband emission is crucial for advancing wide‐color‐gamut organic light‐emitting diode (OLED). Herein, a rigid modification strategy is introduced for iridium(III) complexes to achieve the narrowband red emission with negligible 0–1 peak. By introducing the rigid indolo[3,2,1‐jk]carbazole (ICz) into the cyclometalated ligand, Ir(III) complexes, ICziq‐Ir and ICzqz‐Ir, exhibit pure red phosphorescence with emission peaks at 608 and 613 nm and full widths at half‐maximum (FWHMs) of 37 and 38 nm (0.12 and 0.13 eV) in toluene, respectively. Furthermore, the specific site modification of ICzqz‐Ir greatly suppresses the high‐frequency vibration of the structure, resulting in the narrowband photoluminescent spectrum close to the Gaussian distribution with superior color purity. The OLEDs utilizing ICziq‐Ir and ICzqz‐Ir demonstrate maximum external quantum efficiencies of 21.4 and 17.8% as well as mild efficiency roll‐off. Remarkably, the electroluminescence spectra exhibit similar narrowband red emission with FWHMs of 37 and 43 nm and CIE coordinates of (0.65, 0.35) and (0.66, 0.34), attesting to the excellent color purity of the phosphorescent OLEDs. [ABSTRACT FROM AUTHOR]

The rigid planar architecture of multiple resonance thermally activated delayed fluorescence (MR‐TADF) molecules employing boron/nitrogen (B/N) frameworks typically results in severe aggregation‐caused quenching (ACQ) and spectral broadening. Herein, a steric modification strategy is proposed by incorporating a tetrahedral architecture of triphenylgermanium (TPhGe) into the para‐position of B/N/N, B/N/O, and B/N/S frameworks for the first time, formed three MR‐TADF emitters, BNNGe, BNOGe, and BNSGe, with narrowband emissions ranging from bluish‐green to pure blue. Consequently, these emitters exhibit high photoluminescence quantum yields of > 90% in doped films. Organic light‐emitting diodes (OLEDs) based on BNNGe, BNOGe, and BNSGe demonstrate impressive maximum external quantum efficiencies (EQEmaxs) of 30.1% to 15.5%, and 20.7%, respectively. The unique tetrahedral TPhGe moiety, with its bulky size conformation, effectively separates adjacent MR‐TADF molecules, resulting in efficient luminescence across a broad range of doping concentrations (5–30 wt%) in doped films, thereby successfully suppressing the ACQ in devices. Furthermore, OLEDs containing BNSGe display low‐efficiency roll‐offs because of higher spin‐orbital coupling and reverse intersystem crossing rates of the emitter, attributed to the heavy atom effect. Notably, the device with 5 wt% BNOGe exhibits a pure blue emission peaking at 461 nm, with a narrow full‐width at half‐maximum of 32 nm. [ABSTRACT FROM AUTHOR]

The chiral materials and circularly polarized organic light‐emitting diodes (CP‐OLEDs) have potential applications in 3D display due to the generation of circularly polarized luminescence (CPL). However, achieving a combination of chirality, high efficiency, and narrowband emission for thermally activated delayed fluorescence (TADF) materials has proven to be a challenging endeavor, often involving complicated synthesis and chiral separation processes. In this study, a simple design approach is introduced by direct connection of the multiple resonance (MR) skeleton and chiral (R/S)‐1,1′‐binaphthyl units, obtaining two pairs of chiral MR‐TADF enantiomers (R/S)‐DtCzB‐OBN and (R/S)‐DtCzB‐BN without chiral resolution. These enantiomers exhibit blue‐green emissions with photoluminescence quantum efficiencies of up to 98% in doped films and full‐width at half‐maximum of 22 nm both in toluene and in the device. Furthermore, (R/S)‐DtCzB‐OBN and (R/S)‐DtCzB‐BN display symmetric CPL spectra with dissymmetry factors (gPL) of + 3.86(± 0.317) × 10−4/‐3.37(± 0.317) × 10−4 and + 7.09(± 0.233) × 10−4/‐7.74(± 0.233) × 10−4, respectively. The CP‐OLEDs based on (R/S)‐DtCzB‐OBN and (R/S)‐DtCzB‐BN exhibit impressive maximum external quantum efficiencies of 30.0% and 33.9%, as well as gEL factors of +3.40(± 0.362) × 10−4/‐3.11(± 0.362) × 10−4 and + 7.99(± 0.391) × 10−4/‐8.19(± 0.391) × 10−4, respectively. This research proposes a strategy for directly constructing chiral MR‐TADF materials for high‐performance CP‐OLEDs, avoiding complicated chiral separation. [ABSTRACT FROM AUTHOR]

The development of efficient multi‐resonance thermally activated delayed fluorescence (MR‐TADF) materials with ultra‐narrowband emission presents an ongoing challenge. In this work, a carbazole‐fused dual‐boron embedded MR‐TADF framework is proposed, achieving three emitters, CFDBO, CFDBA, and CFDBCz, via one‐shot borylation with very high yields of over 70%. The emitters display ultra‐narrowband blue emission with peaks ranging from 452 to 479 nm and small full width at half maximum (FWHM) values of only 16–18 nm in dilute toluene solutions. Furthermore, the organic light‐emitting diode (OLED) incorporating CFDBO exhibits pure‐blue emission with a peak of 460 nm and Commission International de l'Eclairage coordinates of (0.14, 0.12). Meanwhile, OLEDs incorporating CFDBA/CFDBCz demonstrate remarkable performances with high external quantum efficiencies of 30.9%/32.4% and exceptionally slender FWHM values of 21/22 nm, representing outstanding performances among reported MR‐TADF materials. [ABSTRACT FROM AUTHOR]

Chiral emitters capable of producing circularly polarized luminescence (CPL) with high dissymmetry factors (g) are crucial for circularly polarized organic light‐emitting diodes (CP‐OLEDs) and 3D display. Herein, sulfonyl binaphthalene is incorporated as both electron acceptor and chiral source into three pairs of thermally activated delayed fluorescence (TADF) enantiomers, (R/S)‐BPSTCZ, (R/S)‐BPSDMAC, and (R/S)‐BPSPXZ, for the first time, combining tert‐butylcarbazole, 9,9‐dimethyl‐9,10‐dihydro‐acridine and phenoxazine electron donors, respectively. These TADF compounds exhibit tunable emissions spanning from deep blue to green, accompanied by high photoluminescence quantum yields. Due to the large distorted angles caused by two sulfonyl units, all enantiomers exhibit pronounced CPL with |gPL| factors of up to 6.0 × 10−3 in doped films. The corresponding CP‐OLEDs display good performances with external quantum efficiencies of up to 28.5% and notable |gEL| factors of up to 8.8 × 10−3, surpassing most CP‐OLEDs based on chiral TADF materials. [ABSTRACT FROM AUTHOR]

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 |gPL| 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 |gEL| 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. [ABSTRACT FROM AUTHOR]

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 |gPL| 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. [ABSTRACT FROM AUTHOR]

This work describes the first hot exciton fluorescent material based on benzo[c][1,2,5]thiadiazole and chiral binaphthol enabling circularly polarized luminescence (CPL) through a chiral perturbation strategy. The new molecular architecture displays CPL, hybridized local and charge transfer (HLCT) properties concurrently. Utilizing it as the emitter, circularly polarized organic light‐emitting diodes (CP‐OLEDs) achieve an external quantum efficiency (EQE) of 7.2% with a good exciton utilization (36%) and a moderate circularly polarized electroluminescence (CPEL) dissymmetry factor (gEL, 2.1 × 10−3). In addition, the CP‐HLCT molecule is sensitized by a thermally activated delayed fluorescence material, significantly ameliorating the efficiency of HLCT fluorescent CP‐OLEDs. Excellent performances of twofold maximum EQE (EQEmax) of 15.3% and 82% exciton utilization are obtained in the sensitized device, regarding an extremely low‐efficiency roll‐off of 2.6% at 1000 cd m−2 as well as CPEL with a gEL value of 2.0 × 10−3. [ABSTRACT FROM AUTHOR]

Click chemistry focuses on the development of highly selective reactions using simple precursors for the exquisite synthesis of molecules. Undisputedly, the CuI‐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. [ABSTRACT FROM AUTHOR]