Fluorescence imaging in the second near‐infrared (NIR‐II) window facilitated by aggregation‐induced emission luminogens (AIEgens) is an emerging research field. NIR‐II AIEgens overcome limitations ...imposed by penetration depth and fluorescence efficiency, offering high‐performance imaging with enhanced precision. Some reported NIR‐II AIEgens demonstrate capabilities for fluorescence and photoacoustic bimodal imaging, and fluorescence imaging guided photothermal therapy, which not only improves diagnosis accuracy but provides an efficient theranostic platform to accelerate preclinical translation as well. This minireview summarizes recent efforts on exploiting NIR‐II AIEgens with regard to molecular design strategies and bioapplications, and puts forward current challenges and promising prospects. This timely sketch should benefit the further exploitation of diverse and multifunctional NIR‐II AIEgens for a wide array of applications.
Fluorescence imaging facilitated by NIR‐II emissive aggregation‐induced emission luminogens (AIEgens) is an emerging research field. This minireview summarizes recent efforts on developing novel NIR‐II AIEgens in terms of molecular design strategies and bioapplications, and discusses current challenges and future prospects.
Aggregation‐induced emission (AIE) describes a photophysical phenomenon in which molecular aggregates exhibit stronger emission than the single molecules. Over the course of the last 20 years, AIE ...research has made great strides in material development, mechanistic study and high‐tech applications. The achievements of AIE research demonstrate that molecular aggregates show many properties and functions that are absent in molecular species. In this review, we summarize the advances in the field of AIE and its related areas. We specifically focus on the new properties of materials attained by molecular aggregates beyond the microscopic molecular level. We hope this review will inspire more research into molecular ensembles at and beyond the meso level and lead to the significant progress in material and biological science.
The importance of the whole picture: Aggregation‐induced emission (AIE) research demonstrates that many properties and functions that are absent in molecular species can be found in molecular aggregates. AIE research thus emphasizes the significance of aggregate science in addition to molecular science for materials development.
The study of purely organic room‐temperature phosphorescence (RTP) has drawn increasing attention because of its considerable theoretical research and practical application value. Currently, organic ...RTP materials with both high efficiency (ΦP > 20%) and a long lifetime (τP > 10 s) in air are still scarce due to the lack of related design guidance. Here, a new strategy to increase the phosphorescence performance of organic materials by integrating the RTP host and RTP guest in one doping system to form a triplet exciplex, is reported. With these materials, the high‐contrast labeling of tumors in living mice and encrypted patterns in thermal printing are both successfully realized by taking advantage of both the long afterglow time (up to 25 min in aqueous media) and high phosphorescence efficiency (43%).
A series of simple organic phosphorescence host–guest materials with high performance are successfully developed. With these materials, high‐contrast labeling of tumors in living mice and encrypted patterns in thermal printing are successfully realized by taking advantage of both their long afterglow time (up to 25 min in aqueous media) and high phosphorescence efficiency (43%).
Non‐doped organic light‐emitting diodes (OLEDs) possess merits of higher stability and easier fabrication than doped devices. However, luminescent materials with high exciton use are generally ...unsuitable for non‐doped OLEDs because of severe emission quenching and exciton annihilation in neat films. Herein, we wish to report a novel molecular design of integrating aggregation‐induced delayed fluorescence (AIDF) moiety within host materials to explore efficient luminogens for non‐doped OLEDs. By grafting 4‐(phenoxazin‐10‐yl)benzoyl to common host materials, we develop a series of new luminescent materials with prominent AIDF property. Their neat films fluoresce strongly and can fully harvest both singlet and triplet excitons with suppressed exciton annihilation. Non‐doped OLEDs of these AIDF luminogens exhibit excellent luminance (ca. 100000 cd m−2), outstanding external quantum efficiencies (21.4–22.6 %), negligible efficiency roll‐off and improved operational stability. To the best of our knowledge, these are the most efficient non‐doped OLEDs reported so far. This convenient and versatile molecular design is of high significance for the advance of non‐doped OLEDs.
Robust emitters, affording high‐performance non‐doped organic light‐emitting diodes with outstanding external quantum efficiencies (EQE) of up to 22.6 % and negligible efficiency roll‐off, have been obtained by molecularly integrating an aggregation‐induced delayed fluorescence (AIDF) luminogen into a host material.
Nonradiative decay invariably competes with radiative decay during the deexcitation process of matter. In the community of luminescence research, nonradiative decay has been deemed less attractive ...than radiative decay. However, all things in their being are good for something and so is nonradiative decay. As the molecular motion‐facilitated nonradiative decay (MMFND) effect is inevitable in photophysical processes, it provides a new avenue to convert the harvested light energy into exploitable forms by harnessing molecular motion. In many cases, active molecular motion enables thermal deactivation from excited states. In this Minireview, recent advances in photothermal and photoacoustic systems with MMFND character are summarized. We believe that this presentation of the rational engineering of molecular motion for efficient photothermal generation will deepen the understanding of the relationship between molecular motion and nonradiative decay and navigate people to rethink the positive aspects of nonradiative decay for the establishment of new light‐controllable techniques.
In the past few years, the molecular motion‐facilitated nonradiative decay (MMFND) effect has been widely used to develop efficient photothermal and photoacoustic systems. To give a timely summary of this emerging field, the present Minireview systematically highlights the underlying mechanism, molecular design principles, and advanced applications of photothermal transduction agents with flexible molecular groups.
Herein the novel tetraphenylethylene (TPE) derivative 1 was designed with an integration of aggregation‐induced emission (AIE), multi‐state mechanochromism and self‐recovery photochromism. The ...molecule was susceptible to grinding, heating and vapor fuming and showed corresponding transition of its emission colors. The heated powder or single crystal of 1 exhibited reversible photochromism. After a short period of UV irradiation, it showed a bright red color, but recovered to its original white appearance within 1 min. The photochromism is due to the formation of photocyclization intermediates upon UV irradiation, while the eversible mechanochromism is attributed to the weak molecular interactions derived from head‐to‐tail stacking of the molecules. This reversible multi‐state, high‐contrasted and rapid responsive mechanochromic and photochromic property cooperatively provide double enhancement of a multimode guarantee in advanced anti‐counterfeiting.
Forgery‐proof: A novel AIE molecule 1 is designed with high‐contrasted and multi‐state mechanochromic and photochromic properties. Based on these properties, 1 shows great potential for application in advanced multidimensional anti‐counterfeiting, which was demonstrated by fabrication of a model banknote.
Superior artificial light‐harvesting systems (ALHSs) require exceptional capacity in harvesting light and transferring energy. In this work, we report a novel strategy to build ALHSs with an ...unprecedented antenna effect (35.9 in solution and 90.4 in solid film). The ALHSs made use of a conjugated polymeric supramolecular network (CPSN), a crosslinked network obtained from the self‐assembly of a pillar5arene‐based conjugated polymeric host (CPH) and conjugated ditopic guests (Gs). The excellent performance of the CPSN could be attributed to the following factors: 1) The “molecular wire effect” of the conjugated polymeric structure, 2) aggregation‐induced enhanced emission (AEE) moieties in the CPH backbone, and 3) high capacity of donor–acceptor energy transfer, and 4) crosslinked structures triggered by the host–guest binding between Gs and CPH. Moreover, the emission of the CPSN could be tuned by using different Gs or varying the host/guest ratio, thus reaching a 96 % sRGB area.
You're the antenna: A conjugated polymeric supramolecular network with aggregation‐induced emission enhancement has been developed as an excellent light‐harvesting system with an unprecedented antenna effect (35.9 in solution and 90.4 in solid film). Moreover, the emission of this network could be tuned, reaching 96 % sRGB area.
Multicolor fluorescent polymeric hydrogels (MFPHs) are three‐dimensionally crosslinked hydrophilic polymer networks with tunable emission color. Different from the classic fluorescent materials that ...are used primarily in dry solid states or solutions, MFPHs exist as highly water‐swollen quasi‐solids. They thus present many promising properties of both solids and solution, including tissue‐like mechanical properties, an intrinsic soft and wet nature, fabulous biocompatibility, along with a responsive volume, shape, and fluorescence color change. These advantageous properties hold great potential in many applications such as sensing, bioimaging, information encoding, encryption, biomimetic actuators, and soft robotics. This Review gives an in‐depth overview of recent progress in the field of MFPHs, with a particular focus on the diverse construction methods and important demonstrated applications. Current challenges and future perspectives on MFPHs are also discussed.
Multicolor fluorescent polymeric hydrogels (MFPHs), rising stars of luminescent materials, are the marriage of multicolor fluorescent materials and polymeric hydrogels. They have many extraordinary properties, such as a tissue‐like modulus, an intrinsic soft and wet nature, and fluorescence color change. In this Review, recent progress in MFPHs is summarized, with a particular focus on the construction methods and important applications.
With recent progress in photothermal materials, organic small molecules featured with flexibility, diverse structures, and tunable properties exhibit unique advantages but have been rarely applied in ...solar‐driven water evaporation owing to limited sunlight absorption resulting in low solar–thermal conversion. Herein, a stable croconium derivative, named CR‐TPE‐T, is designed to exhibit the unique biradical property and strong π–π stacking in the solid state, which facilitate not only a broad absorption spectrum from 300 to 1600 nm for effective sunlight harvesting, but also highly efficient photothermal conversion by boosting nonradiative decay. The photothermal efficiency is evaluated to be 72.7% under 808 nm laser irradiation. Based on this, an interfacial‐heating evaporation system based on CR‐TPE‐T is established successfully, using which a high solar‐energy‐to‐vapor efficiency of 87.2% and water evaporation rate of 1.272 kg m−2 h−1 under 1 sun irradiation are obtained, thus making an important step toward the application of organic‐small‐molecule photothermal materials in solar energy utilization.
A stable croconium derivative, “CR‐TPE‐T”, is designed to exhibit the unique biradical property and strong π–π stacking in the solid state, which facilitate not only a broad absorption spectrum from 300 to 1600 nm for effective sunlight harvesting, but also highly efficient photothermal conversion by boosting nonradiative decay, enabling a high solar‐energy‐to‐vapor efficiency of 87.2% under one sun irradiation.
Many luminescent stimuli responsive materials are based on fluorescence emission, while stimuli-responsive room temperature phosphorescent materials are less explored. Here, we show a kind of ...stimulus-responsive room temperature phosphorescence materials by the covalent linkage of phosphorescent chromophore of arylboronic acid and polymer matrix of poly(vinylalcohol). Attributed to the rigid environment offered from hydrogen bond and B-O covalent bond between arylboronic acid and poly(vinylalcohol), the yielded polymer film exhibits ultralong room temperature phosphorescence with lifetime of 2.43 s and phosphorescence quantum yield of 7.51%. Interestingly, the RTP property of this film is sensitive to the water and heat stimuli, because water could destroy the hydrogen bonds between adjacent poly(vinylalcohol) polymers, then changing the rigidity of this system. Furthermore, by introducing another two fluorescent dyes to this system, the color of afterglow with stimulus response effect could be adjusted from blue to green to orange through triplet-to-singlet Förster-resonance energy-transfer. Finally, due to the water/heat-sensitive, multicolor and completely aqueous processable feature for these three afterglow hybrids, they are successfully applied in multifunctional ink for anti-counterfeit, screen printing and fingerprint record.
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