Purely organic emitters that can efficiently utilize triplet excitons are highly desired to cut the cost of organic light‐emitting diodes (OLEDs), but most of them require complicated doping ...techniques for their fabrication and suffer from severe efficiency roll‐off. Herein, we developed novel luminogens with weak emission and negligible delayed fluorescence in solution but strong emission with prominent delayed components upon aggregate formation, giving rise to aggregation‐induced delayed fluorescence (AIDF). The concentration‐caused emission quenching and exciton annihilation are well‐suppressed, which leads to high emission efficiencies and efficient exciton utilization in neat films. Their nondoped OLEDs provide excellent electroluminescence efficiencies of 59.1 cd A−1, 65.7 lm W−1, and 18.4 %, and a negligible current efficiency roll‐off of 1.2 % at 1000 cd m−2. Exploring AIDF luminogens for the construction of nondoped OLEDs could be a promising strategy to advance device efficiency and stability.
Neat films of luminogens with aggregation‐induced delayed fluorescence (AIDF) were employed in nondoped OLEDs. These systems afford remarkable current, power, and external quantum efficiencies as the concentration‐caused emission quenching and exciton annihilation are well suppressed, which leads to high emission efficiencies and efficient exciton utilization in the neat films.
Development of new polymerizations based on triple-bond building blocks has received considerable research attention, from which polymers with unique structures and advanced functions can be ...generated. In this review, we summarize the research efforts on using alkynes and nitrogen-containing triple bonds as building blocks to prepare polymers with linear and topological structures since 2010. The metathesis polymerization and polyaddition of mono- and di-substituted acetylenes, the Cu(I)-catalyzed and metal-free azide-alkyne click polymerization, the thiol-yne click polymerization, polycyclotrimerization of diynes, and the polymerizations based on cyanide and isocyanide monomers are discussed in detail. Moreover, the unique stoichiometric imbalanced polymerization based on alkynes is also briefly introduced. The functions and applications of polymers, produced from these developed polymerization reactions, such as aggregation-induced emission, self-healing, fluorescent patterning, liquid crystal, fluorescence sensing, explosive detection, chiral catalysis and gas permeability are also reviewed.
With the continuous advancement of information technology, the requirements for the information storage capacity of materials are getting higher and higher. However, information code materials ...usually only store a single piece of information. In order to improve their storage capacity, aggregation‐induced emission (AIE) supramolecular adhesive hydrogels with different fluorescent colors are prepared, and a “Codes in Code” method is used to demonstrate the storage capacity for large amounts of information. Four kinds of poly(vinyl alcohol) (PVA) supramolecular hydrogels with different fluorescent colors are prepared; based on the hydrogen bonds on the hydrogel surface, these hydrogels can be assembled into a hydrogel, G5, which shows multiple fluorescent colors under the irradiation of UV light. When many 1D barcode patterns or/and 2D code patterns are incorporated into G5, not only a kind of 3D information but also plenty of 1D or/and 2D information can be stored. Therefore, the information codes prepared by the “Codes in Code” method can store a large amount of information.
The construction of AIE supramolecular adhesive hydrogels showing different fluorescent colors and the use of a “Codes in Code” method, incorporating 1D barcode or/and 2D code patterns into a 3D code pattern, to demonstrate the storage capacity of large amounts of information, are reported. This study realizes a great improvement of the storage capacity of information code materials.
Polymeric materials are susceptible to the chain re‐conformation, reorientation, slippage, and bond cleavage upon mechanical stimuli, which are likely to further grow into macro‐damages and ...eventually lead to the compromise or loss of materials performance. Therefore, it is of great academic importance and practical significance to sensitively detect the local mechanical states in polymers and monitor the dynamic variations in polymer structures and properties under external forces. Mechanochromic fluorescent polymers (MFP) are a class of smart materials by utilizing sensitive fluorescent motifs to detect polymer chain events upon mechanical stimuli. Taking advantage of the unique aggregation‐induced emission (AIE) effect, a variety of MFP systems that can self‐report their mechanical states and mechano‐induced structural and property changes through fluorescence signals have been developed. In this feature article, an overview of the recent progress on MFP systems enabled by AIE process is presented. The main design principles, including physically doping dispersed or microencapsulated AIE luminogens (AIEgens) into polymer matrix, chemically linking AIEgens in polymer backbones, and utilizing the clusterization‐triggered emission of polymers containing nonconventional luminogens, are discussed with representative examples. Perspectives on the existing challenges and problems in this field are also discussed to guide future development.
Mechanochromic fluorescent polymers (MFPs) can change their fluorescence properties with local polymer deformation responses under mechanical forces. The unique aggregation‐induced emission (AIE) processes enable the development of diverse MFPs. The main design principles include physically doping dispersed or microencapsulated AIE luminogens (AIEgens) into polymer matrix, chemically bonding AIEgens in polymer backbones, and the rational utilization of clusteroluminescent polymers.
For the development of organic light-emitting diodes (OLEDs) and their application in the display and lighting fields, efficiency, stability and cost are the most important factors to be considered. ...In particular, the performance of blue materials is a key factor that influences the extent of OLED applications. Although blue phosphors with triplet emission can realize high efficiency, their bad stability and severe efficiency roll-off at high luminance greatly hinder their applications. Comparatively speaking, currently, blue fluorophores with singlet emission are still the best choice due to their advantages of long lifetime and low cost. This review mainly focuses on advances in high performance blue OLEDs based on fluorescence emitters from the perspective of mechanisms and device structures. Efficient methods to harvest triplets, molecular orientation effects and stability are discussed in detail. We also demonstrate future directions for the design of materials and device structures for high performance blue fluorescent OLEDs.
This review summarizes recent advances in blue OLEDs based on fluorescence emitters, especially focusing on the different mechanisms involving the emitters and devices.
The development of multifunctional nanoplatforms has been recognized as a promising strategy for potent photodynamic theranostics. Aggregation‐induced emission (AIE) photosensitizers undergoing ...Type‐I reactive oxygen species (ROS) generation pathway appear as potential candidates due to their capability of hypoxia‐tolerance, efficient ROS production, and fluorescence imaging navigation. To further improve their performance, a facile and universal method of constructing a type of glutathione (GSH)‐depleting and near‐infrared (NIR)‐regulated nanoplatform for dual‐modal imaging‐guided photodynamic therapy (PDT) is presented. The nanoplatforms are obtained through the coprecipitation process involving upconversion nanoparticles (UCNPs) and AIE‐active photosensitizers, followed by in situ generation of MnO2 as the outer shell. The introduction of UCNPs actualizes the NIR‐activation of AIE‐active photosensitizers to produce ·OH as a Type‐I ROS. Intracellular upregulated GSH‐responsive decomposition of the MnO2 shell to Mn2+ realizes GSH‐depletion, which is a distinctive approach for elevating intracellular ·OH. Meanwhile, the generated Mn2+ can implement T1‐weighted magnetic resonance imaging (MRI) in specific tumor sites, and mediate the conversion of intracellular H2O2 to ·OH. These outputs reveal a triple‐jump ·OH production, and this approach brings about distinguished performance in FLI‐MRI‐guided PDT with high‐efficacy, which presents great potential for future clinical translations.
A triple‐jump photodynamic theranostics protocol is explored for high‐efficacy cancer treatment, by establishing an intelligent glutathione‐depleting and NIR‐regulated theranostic nanoplatform comprising a MnO2 nanoshell, upconversion nanoparticles, and aggregation‐induced emission‐active Type‐I photosensitizers.
Purely organic emitters with high exciton utilization have attracted considerable attention in the field of organic light‐emitting diodes (OLEDs). However, most reported thermally activated delayed ...fluorescence (TADF) emitters suffer from concentration quenching and exciton annihilation, so that they require complicated doping technique in OLED application. Nonetheless, the serious efficiency roll‐off remains a big challenge for doped OLEDs of TADF emitters. To simplify the fabrication process and improve the stability of devices, developing organic emitters for nondoped OLEDs is of high significance. This progress report provides a systematic summary and comments on the recent advances of efficient organic luminescent materials including conventional TADF materials and novel aggregation‐induced delayed fluorescence (AIDF) luminogens for the fabrication of high‐performance nondoped OLEDs. Their molecular design strategies, photophysical properties, and electroluminescence performances in nondoped OLEDs are elucidated in depth. The newly emerged organic materials with AIDF nature could be a promising direction for exploring light‐emitting materials to advance efficiency and stability of OLEDs.
Nowadays, nondoped organic light‐emitting diodes (OLEDs) have attracted much attention because of process simplicity, reduced fabrication cost, and advanced stability. Remarkably, aggregation‐induced delayed fluorescence luminogens have merits of the full utilization of singlet and triplet excitons and the efficient suppression of concentration‐caused emission quenching and exciton annihilation, which make them ideal materials for the fabrication of nondoped OLEDs.
Conventional π-conjugated luminophores suffer from problems such as emission quenching, biotoxicity, environmental pollution, etc. The emerging nonconjugated and nonaromatic clusteroluminogens ...(CLgens) are expected to overcome these stubborn drawbacks, so research of CLgens shows great significance not only for practical application but also for the construction of fundamental photophysical theories. This perspective summarizes the unusual features of CLgens in comparison to traditional chromophores, such as nonconjugated molecular structures, unmatched absorption and excitation, excitation-dependent luminescence, multiple emission peaks, and room-temperature phosphorescence. Different from the theory of through-bond conjugation in π-conjugated luminophores, through-space interactions, including through-space n···n interaction and through-space n···π interaction, are regarded as the emitting sources of nonconjugated CLgens. In addition, the formation of network clusters is proposed as an efficient strategy to improve the performance of CLgens, and their potential applications of anticounterfeiting, photoelectronic devices, and bioimaging are prospected.
Aggregation-induced emission of siloles Zhao, Zujin; He, Bairong; Tang, Ben Zhong
Chemical science (Cambridge),
2015-Oct-01, Letnik:
6, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Aggregation-induced emission (AIE) is a unique and significant photophysical phenomenon that differs greatly from the commonly acknowledged aggregation-caused emission quenching observed for many ...π-conjugated planar chromophores. The mechanistic decipherment of the AIE phenomenon is of high importance for the advance of new AIE systems and exploitation of their potential applications. Propeller-like 2,3,4,5-tetraphenylsiloles are archetypal AIE-active luminogens, and have been adopted as a core part in the design of numerous luminescent materials with diverse functionalities. In this review article, we elucidate the impacts of substituents on the AIE activity and shed light on the structure-property relationship of siloles, with the aim of promoting the judicious design of AIE-active functional materials in the future. Recent representative advances of new silole-based functional materials and their potential applications are reviewed as well.
Recent advances in the structure-property relationship decipherment and luminescent functional materials development of AIE-active siloles are reviewed.
Tailor‐made red thermally activated delayed fluorescence (TADF) molecules comprised of an electron‐withdrawing pyrazino2,3‐f1,10phenanthroline‐2,3‐dicarbonitrile core and various electron‐donating ...triarylamines are developed. They can form intramolecular hydrogen‐bonding, which is conducive to improving emission efficiency and promoting horizontal orientation and show near infrared (NIR) emissions (692–710 nm) in neat films and red delayed fluorescence (606–630 nm) with high photoluminescence quantum yields (73–90%) in doped films. They prefer horizontal orientation with large horizontal dipole ratios in films, rendering high optical out‐coupling factors (0.39–0.41). Their non‐doped OLEDs exhibit NIR lights (716–748 nm) with maximum external quantum efficiencies (ηext,max) of 1.0–1.9%. And their doped OLEDs radiate red lights (606–648 nm) and achieve record‐beating ηext,max of up to 31.5%. These new red TADF materials should have great potentials in display and lighting devices.
Tailor‐made red thermally activated delayed fluorescence molecules with intramolecular hydrogen bonding are developed, which exhibit excellent photoluminescence efficiencies and large horizontal dipole ratios, and thus furnish the state‐of‐the‐art red and near infrared OLEDs, with a record‐high external quantum efficiency of 31.5 %.
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