Energy-efficient and deep-blue organic light-emitting diode (OLED) with long operating stability remains a key challenge to enable a disruptive change in OLED display and lighting technology. Part of the challenge is associated with a very narrow choice of the robust host materials having over 3 eV triplet energy level to facilitate efficient deep-blue emission and deliver excellent performance in the OLED device. Here we show the molecular design of new 1,3,5-oxadiazines (NON)-host materials with high triplet energy over 3.
View Article and Find Full Text PDFLinear gold complexes of the "carbene-metal-amide" (CMA) type are prepared with a rigid benzoguanidine amide donor and various carbene ligands. These complexes emit in the deep-blue range at 424 and 466 nm with 100% quantum yields in all media. The deep-blue thermally activates delayed fluorescence originates from a charge transfer state with an excited state lifetime as low as 213 ns, resulting in fast radiative rates of 4.
View Article and Find Full Text PDFOrganic thermally activated delayed fluorescence (TADF) materials have been widely investigated due to their impressive electronic properties and applied potential for the third generation of organic light-emitting diodes (OLED). We present organic TADF material () based on the strained benzoguanidine donor and compare it with the benchmark carbazole-based material (). Extended π-conjugation in material results in yellow-green luminescence at 512 nm with a fast radiative rate of 5.
View Article and Find Full Text PDFA series of carbene-gold-acetylide complexes [(BiCAAC)AuCC] C H (n = 1, Au1; n = 2, Au2; n = 3, Au3; BiCAAC = bicyclic(alkyl)(amino)carbene) have been synthesized in high yields. Compounds Au1-Au3 exhibit deep-blue to blue-green phosphorescence with good quantum yields up to 43% in all media. An increase of the (BiCAAC)Au moieties in gold complexes Au1-Au3 increases the extinction coefficients in the UV-vis spectra and stronger oscillator strength coefficients supported by theoretical calculations.
View Article and Find Full Text PDFGold-centered carbene-metal-amides (CMAs) containing cyclic (alkyl)(amino)carbenes (CAACs) are promising emitters for thermally activated delayed fluorescence (TADF). Aiming at the design and optimization of new TADF emitters, we report a density functional theory study of over 60 CMAs with various CAAC ligands, systematically evaluating computed parameters in relation to photoluminescence properties. The CMA structures were primarily selected based on experimental synthesis prospects.
View Article and Find Full Text PDFThe molecular design of metal-free organic phosphors is essential for realizing persistent room-temperature phosphorescence (pRTP) despite its spin-forbidden nature. A series of halobenzonitrile-carbazoles has been prepared following a one-pot nucleophilic substitution protocol involving commercially available and laboratory-synthesized carbazoles. We demonstrate how halo- and cyano-substituents affect the molecular geometry in the crystal lattice, resulting in tilt and/or twist of the carbazole with respect to the phenyl moiety.
View Article and Find Full Text PDFA series of σ-SiH copper complexes with different carbazole derivatives have been synthesized and characterized that adopt a neutral SiP ligand (SiP = (2-PrPCH)SiMe) and present photophysical properties. A previously reported copper complex (SiP)Cu(carbazolide), and its derivatives showed that tuning of the emission properties is possible by incorporating various substituents on the carbazolide moiety. Newly synthesized copper complexes (-) having 3,6-dichlorocarbazolide, 3,6-dibromocarbazolide, 1-fluorocarbazolide, 3,6-dimethylcarbazolide, and 3,6-diphenylcarbazolide show a range of λ values of emission from 418 to 511 nm.
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