Luminescent materials with efficient solid-state emissions are important for the advancement of optoelectronics. Recently, a new class of propeller-like luminogenic molecules with aggregationinduced emission (AIE) characteristics has drawn increasing research interest. Among them, tetraphenylethene (TPE) is an archetypal luminogen with a simple molecule structure but shows a splendid AIE effect. Utilizing TPE as a building block, an effective strategy to create efficient solid-state emitters is developed. In this feature article, we review mainly our recent work on the construction of luminogenic materials from TPE and present their applications in organic light-emitting diodes. The applicability of the synthetic strategy and the utility of the resulting materials are demonstrated.
Recent advances in the structure–property relationship decipherment and luminescent functional materials development of AIE-active siloles are reviewed.
Ultrabright organic dots with aggregation-induced emission characteristics (AIE dots) are prepared and shown to exhibit a high quantum yield, a, large two-photon absorption cross-section, and low in vivo toxicity. Real-time two-photon intravital blood vascular imaging in various tissues substantiates that the AIE dots are effective probes for in vivo vasculature imaging in a deep and high-contrast manner.
Development of highly efficient circularly polarized organic light‐emitting diodes (CPOLEDs) has gained increasing interest as they show improved luminous efficiency and high contract 3D images in OLED displays. In this work, a series of binaphthalene‐containing luminogenic enantiomers with aggregation‐induced emission (AIE) and delayed fluorescence properties is designed and synthesized. These molecules can emit from green to red light depending on the solvent polarity due to the twisted intramolecular charge transfer effect. However, their solid powders show bright light emissions, demonstrating a phenomenon of AIE. All the molecules exhibit Cotton effects and circularly polarized luminescence in toluene solution and films. Multilayer CPOLEDs using the doped and neat films of the molecules as emitting layers are fabricated, which exhibit high external quantum efficiency of up to 9.3% and 3.5% and electroluminescence dissymmetry factor (gEL) of up to +0.026/−0.021 and +0.06/−0.06, respectively. Compared with doped CPOLEDs, the nondoped ones show higher gEL and much smaller current efficiency roll‐off due to the stronger AIE effect. By altering the donor unit, the electroluminescence maximum of the doped film can vary from 493 to 571 nm. As far as it is known, this is the first example of efficient CPOLEDs based on small chiral organic molecules.
Luminescent materials with thermally activated delayed fluorescence (TADF) can harvest singlet and triplet excitons to afford high electroluminescence (EL) efficiencies for organic light‐emitting diodes (OLEDs). However, TADF emitters generally have to be dispersed into host matrices to suppress emission quenching and/or exciton annihilation, and most doped OLEDs of TADF emitters encounter a thorny problem of swift efficiency roll‐off as luminance increases. To address this issue, in this study, a new tailor‐made luminogen (dibenzothiophene‐benzoyl‐9,9‐dimethyl‐9,10‐dihydroacridine, DBT‐BZ‐DMAC) with an unsymmetrical structure is synthesized and investigated by crystallography, theoretical calculation, spectroscopies, etc. It shows aggregation‐induced emission, prominent TADF, and interesting mechanoluminescence property. Doped OLEDs of DBT‐BZ‐DMAC show high peak current and external quantum efficiencies of up to 51.7 cd A−1 and 17.9%, respectively, but the efficiency roll‐off is large at high luminance. High‐performance nondoped OLED is also achieved with neat film of DBT‐BZ‐DMAC, providing excellent maxima EL efficiencies of 43.3 cd A−1 and 14.2%, negligible current efficiency roll‐off of 0.46%, and external quantum efficiency roll‐off approaching null from peak values to those at 1000 cd m−2. To the best of the authors' knowledge, this is one of the most efficient nondoped TADF OLEDs with small efficiency roll‐off reported so far.
Efficient synthesis of poly(enamine)s has been a great challenge because of their poor stability, poor solubility, and low molecular weights. In this work, a spontaneous amino-yne click polymerization for the efficient preparation of poly(enamine)s was established, which could proceed with 100% atom efficiency under very mild conditions without any external catalyst. Through systematic optimization of the reaction conditions, several soluble and thermally stable poly(β-aminoacrylate)s with high molecular weights (M up to 64400) and well-defined structures were obtained in excellent yields (up to 99%). Moreover, the polymerization can perform in a regio- and stereospecific fashion. Nuclear magnetic resonance spectra analysis revealed that solely anti-Markovnikov additive products with 100% E-isomer were obtained. The reaction mechanism was well demonstrated with the assistance of density functional theory calculations. In addition, by introducing the tetraphenylethene moiety, the resulting polymers exhibit unique aggregation-induced emission characteristics and could be applied in explosives detection and bioimaging. This polyhydroamination is a new type of click polymerization and opens up enormous opportunities for preparing functional polymeric materials.
Two is better than one: a luminogen comprised of two units of tetraphenylethene (BTPE) emits more efficiently than that with one tetraphenylethene unit in the solid state; self-assembly of the BTPE molecules affords crystalline microfibers that fluoresce in 100% efficiency, giving the largest effect of aggregation-induced emission (alpha(AIE)-->infinity); BTPE-based electroluminescence devices emit in current efficiency up to approximately 7.3 cd/A.
Phosphindole oxide-based photosensitizers with Type I reactive oxygen species generation ability are developed and used for endoplasmic reticulum stress-mediated photodynamic therapy of tumors.
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