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The development of persistent room‐temperature phosphorescent (pRTP) hydrogels is important for the practical applications of organic phosphors. Unfortunately, the phosphorescence emission of nontraditional luminogens (NTLs) can be strongly quenched by water in hydrogel networks. Herein, a series of pRTP organohydrogels based on NTLs are prepared by dissolving poly(vinyl alcohol) (PVA), biuret (BIU) and poly(maleic acid) (PMAc) (or other nonaromatic macromolecular acids) in a glycerol/water mixed solvent, followed by a simple freezing‐thawing treatment. Very impressively, the organohydrogel exhibits remarkable excitation‐dependent and metal cation‐responsive phosphorescence with a maximum lifetime up to 782.8 ms at ambient conditions. Moreover, the organohydrogels treated with metal cations also have excitation‐dependent phosphorescence. Multidimensional information encryption can be achieved by simply printing solutions of metal cations onto the gel surface and switching the irradiation lights, or using gel blocks prepared with different macromolecular acids. Structural characterizations, mechanical tests, and comparative studies prove that hydrogen bonding between BIU and macromolecular chains leads to rigidification of molecular conformations and the cooperative effect of the components leads to the pRTP of the organohydrogels. This work provides a reliable strategy for the preparation of nonaromatic phosphorescent hydrogels with long afterglows and greatly expands the practical applications of phosphorescent materials. [ABSTRACT FROM AUTHOR]

Significant advances are made in understanding the structure‐property relationship in room‐temperature phosphorescence (RTP) materials. For example, intramolecular charge transfer (ICT) structural molecules based on electron donors(D) and electron acceptors(A) are an efficient method to achieve RTP. However, the ability to precisely regulate the singlet‐triplet energy gap (ΔEST) through molecular design to control RTP emissions remains constrained. Herein, a group of 4BN‐NP and 5BN‐NP isomers is reported with D and A position isomerization, where 4BN‐NP exhibits a photo‐induced orange afterglow phenomenon in PMMA. Calculations show that the spin‐orbit coupling (SOC) value of 4BN‐NP is greater compared to 5BN‐NP and the intersystem crossing (ISC) channel is more efficient, resulting in a smaller ΔEST value for 4BN‐NP. This indicates that the short ICT channel is more conducive to inducing phosphorescence emission. In addition, compound 4BN‐NP co‐doped with red fluorescent dyes (RhB, Rh6G, and RBNN) in PMMA produces phosphorescence resonance energy transfer (PRET), inducing red afterglow emission. Surprisingly, light‐activated yellow RTP can be obtained by attaching 4BN‐NP with polymethyl methacrylate (PMMA) to nylon filaments, and its phosphorescence intensity does not diminish even when it is immersed in water containing detergent solution, thus expanding the prospects of its application in textile encryption. [ABSTRACT FROM AUTHOR]

Some marine animals form long‐lived luminescence for predation, communication, camouflage, and anti‐predation. These marine animals demonstrate soft nature, sustainable glowing, and underwater emission, which are difficult to achieve in synthetic room temperature phosphorescence (RTP) materials. Inspired by these marine animals, here the study reports RTP hydrogels that show long‐lived phosphorescence (lifetime >500 ms and afterglow >10 s) in water. Exceptional underwater mechanical properties are simultaneously achieved, including tensile strength of 5.1 MPa, tensile strain of 452%, and toughness of 19.3 MJ m−3. The key to this achievement lies in the in situ phase separation microarchitecture formed between polyacrylamide (PAM) and its partial hydrolysates, which confines the motions of polymer chains and protects vulnerable triplet excitons from quenching of water. Such a strategy shows the merits of facile fabrication without laborious synthesis. In addition, these RTP hydrogels offer repeatable photoprinting and highly stability in water, providing a versatile platform for underwater applications of RTP materials, including information encryption and camouflage of marine animals. [ABSTRACT FROM AUTHOR]

Hybrid metal halides (HMHs) with time‐resolved luminescence behavior promise to be a breakthrough in multi‐level anti‐counterfeiting, but controlling the dynamic switching between phosphorescence and fluorescence is extremely challenging. Herein, an array of 0D HMHs is constructed by screening the π‐conjugated ligand with room‐temperature phosphorescence (RTP). Compared to the organic chromophore, (ETPP)2ZrCl6 possesses a misaligned stacking and rigid structure, contributing to an improved phosphorescence quantum yield (ΦP = 27.50%) and an extended phosphorescence lifetime (τ = 0.6234 s), as the intervening of inorganic unit [ZrCl6]2− suppresses the energy losses caused by nonradiative relaxation and prompts the intersystem crossover (ISC) process. Not only that, the interplay of phosphorescence‐fluorescence dual‐mode emission can be intelligently controlled by doping the active metal Te4+, resulting in a dynamic switching between RTP phosphorescence and self‐trapped exciton (STE) fluorescence. DFT calculations reveal the governing origins of RTP‐STE from the intermolecular ISC channels and spin‐orbit coupling (SOC) coefficients. These precise images into periodic pixelated arrays enable the multi‐level anti‐counterfeiting and information encryption. This work proposes a fluorescence‐phosphorescence co‐modulating strategy under the premise of dissecting the structural origins for optimizing RTP phosphorescence, which paves the way for designing high‐security‐level anti‐counterfeiting materials. [ABSTRACT FROM AUTHOR]

The efficient utilization of clean and safe sunlight as an excitation source for room‐temperature phosphorescent (RTP) materials is crucial for practical applications in solar energy. Herein, sunlight‐activated RTP nitrogen‐doped carbon dots @ alumina (N‐CDs@Al2O3) composites with long lifetime and exceptional stability are designed and fabricated using an in situ preparation strategy. The N‐CDs@Al2O3 display bright yellow RTP (more than 18 s to the naked eye) when activated by sunlight. The results indicate that the introduction of nitrogen into the CDs not only promotes the effective filling of triplet excitons but also facilitates the red‐shift of the absorption spectrum of the CDs. The high rigidity structure of Al2O3 and stable strong covalent bonds effectively protect the triplet excitons. Additionally, the numerous oxygen vacancy defects formed under appropriate calcination conditions effectively store and release triplet excitons. Finally, the application of N‐CDs@Al2O3 in multi‐color 3D artworks, defense markings, and emergency signs is demonstrated. This work provides design principles and feasible strategies for the development of new sunlight‐activated RTP materials. [ABSTRACT FROM AUTHOR]

Organic afterglow can be generated from persistent thermally activated delayed fluorescence (pTADF) or organic ultralong room temperature phosphorescence (OURTP), but the pTADF plus OURTP type organic afterglow is challenging to achieve, especially for the color‐tunable and high‐temperature ones. Herein, an accessible strategy toward such dual‐mode afterglow is presented by doping the indolo[3,2‐b]carbazole (ICZ‐p1) into polymethyl methacrylate (PMMA). The resulting films exhibit photo‐activated afterglow with two persistent emission peaks of ca. 435 and 497 nm. Impressively, their longest lifetimes respectively reach to 2.28 and 2.47 s at 298 K, along with 0.32 and 0.42 s at 360 K, enabling the afterglow at room and high temperature. Experimental and theoretical results reveal that the photo‐activated afterglow is associated with the elimination of molecular O2 inside film and composed by the pTADF with multi‐resonance (MR) effect and OURTP. By altering the temperature from 77 to 358 K, the color‐tunable afterglows of green and blue are harvested at such temperature ranges. Benefiting from the multi‐resonance thermally activated delayed fluorescence (MRTADF) characteristics, this emitter can release narrow‐band electroluminescence. Consequently, the results obtained here may offer important references for chasing MRTADF plus OURTP‐type dual‐mode organic afterglow showing color‐tunable and high‐temperature features. [ABSTRACT FROM AUTHOR]

Supramolecular organic framework (SOF) has recently garnered significant research interest in the field of luminescent materials. However, SOF with room‐temperature phosphorescence emission in solution is very rare due to the quenching of dissolved oxygen and free molecular motions, which would lead to nonradiative deactivation of triplet exciton in liquid state. In this work, a 3D cationic phosphorescent SOF is synthesized through host‐guest interaction between CB[8] and a tetrahedral monomer TBBP, which can rapidly adsorb anionic guests in solution. When anionic dyes are introduced, triplet to singlet Förster resonance energy transfer (TS‐FRET) in solution can be achieved, and delayed fluorescence with large Stokes shift can be realized. Additionally, when anionic drugs are introduced, the phosphorescence of TBBP‐CB[8] can be quenched due to charge transfer, enabling the detection of drugs through phosphorescence signals. Taking advantage of the fast adsorption property of 3D SOF, an INHIBIT logic gate with three inputs and two outputs is constructed. These findings provide a novel method to prepare phosphorescent functional materials and a new pathway to construct TS‐FRET system in solution. [ABSTRACT FROM AUTHOR]

Organic room‐temperature phosphorescence (RTP) materials are actively explored as attractive candidates for optoelectronic and bioelectronics applications given their unique long‐lived excited‐state features and inherent merits of low‐cost, appreciable functionality, and good biocompatibility. In recent years, many efforts in molecular design and aggregation modulation are devoted to achiev efficient RTP from organics, among which an emerging strategy focuses on confining chromophores within polymer matrices. Polymers possess intertwined chains making them a good platform to restrain the nonradiative decays and quenching, allowing the triplet excitons to survive a long time enough for emission at room temperature. Progress relating to polymer‐based organic RTP materials is highlighted as a new creative subject in the field. This review outlines recent advancements in polymer‐based organic RTP materials. The fundamental mechanism of organic RTP is first presented. Thereafter, design considerations and strategies to construct polymer‐based organic RTP materials are summarized in detail. Several promising progresses in the proposed use of these RTP materials, such as encryption and anti‐counterfeiting, sensors, and bioimaging are overviewed. Finally, the challenges and future perspectives are discussed to emphasize the directions that deserve focus attention in the field. [ABSTRACT FROM AUTHOR]

Room temperature phosphorescent (RTP) materials have triggered wide interests because of their excellent performance and various promising applications. However, conventional RTP materials possessing color‐tunable and ultralong afterglow often suffer from low phosphorescent emission efficiency. Herein, a long lifetime and high‐efficiency RTP emission system composed of boric acid as the host matrix and organic phosphors as guest molecules is constructed by suppressing the non‐radiative transition process and promoting the triplet exciton of the phosphors. The synergistic effect of the physically limited domain and supramolecular anchoring also contributes to the ultralong lifetime (up to 1.85 s) and high phosphorescence quantum yield (up to 53%). The afterglow can be visually observed for 30 s. With a large overlap of π‐conjugated chromophores, the emission peak of RTP redshifted, realizing cyan, green, and red afterglow in the monochromatic domain. In addition, the emission of colorful afterglow and white afterglow is adjustable with the different co‐doping ratios. Finally, the application of RTP materials to anti‐counterfeiting encryption is demonstrated. [ABSTRACT FROM AUTHOR]

Organic photoluminescent materials exhibiting room‐temperature phosphorescence (RTP) have attracted widespread attention. However, most of them can emit phosphorescence only in the solid state, which strongly limits their applications. Herein, a type of phosphorescent hydrogel with excellent mechanical properties is prepared by immersing an as‐prepared poly(vinyl alcohol) (PVA) hydrogel in a poly(sodium maleate) solution and then in a CaCl2 solution, followed by drying under stretching at 90 °C and finally soaking it in deionized water until equilibrium swelling to produce poly(vinyl alcohol)/poly(calcium maleate)‐DS (PVA/PMACa‐DS) hydrogels. Such hydrogels exhibit excellent mechanical properties, showing tensile strengths up to 15 MPa, due to the presence of strong hydrogen bonding and especially ionic bonding. The PVA/PMACa‐DS hydrogels emit varied phosphorescence emission colors from blue to yellow‐green upon excitation with 312–400 nm light, with a maximum lifetime of 13.4 ms. Experiments and theoretical calculations demonstrate that ionic crosslinking between Ca2+ and nonconventional chromophores prevents the contact of the nonconventional chromophores with water molecules and hence restricts nonradiative decay, leading to RTP emission. This work provides a reliable strategy for designing RTP hydrogels with excellent mechanical properties based on nonaromatic polymers for emerging applications. [ABSTRACT FROM AUTHOR]

The excited‐state tuning of luminescent metal–organic compounds has made great progress in the fields of optical imaging, photocatalysis, photodynamic therapy, light‐emitting devices, sensors, and so on. Although metal–organic compounds with high luminescence efficiency can be realized via enhanced molecular rigidity and heavy‐atom effect, their corresponding luminescence lifetimes are still limited on the order of a nanosecond to a millisecond, owing to the inherent competition between luminous efficiency and lifetime. Therefore, the advanced applications (i.e., persistent afterglow imaging, information security, anti‐counterfeiting, and smart materials, among others) related with long persistent luminescence (LPL, typically with the excited‐state lifetime larger than millisecond) are seriously hindered. This review gives a timely and systematic summary of metal–organic compounds for realizing room‐temperature phosphorescence (RTP)‐type and thermally activated delayed fluorescence (TADF)‐type LPL during last few years. Particularly, based on the perspectives of time, space, and energy dimensions, fundamental materials design and coordination assembly are systematically described for the first time. Moreover, the internal and external factors of influencing the LPL properties in terms of luminescence efficiency, lifetime, and color are illustrated. Last but not least, perspectives and challenges are also discussed for developing LPL from metal–organic compounds. [ABSTRACT FROM AUTHOR]

In contrast to their fluorescence counterparts, stimuli‐responsive organic afterglow materials display distinct advantages to function normally in the presence of strong fluorescence background. However, most of the stimuli‐responsive afterglow materials can only work in their solid states with those in aqueous medium being rarely reported. In addition, the types of these materials are limited to mechanical force‐, pH‐, ion‐, and temperature‐responsive ones. Here, a serendipitous finding of sonication‐responsive organic afterglow emulsions in aqueous medium is reported. The afterglow emulsions are produced by dopant‐matrix strategy and emulsion technique. In‐depth studies reveal that the key to achieve the sonication responsiveness is the selection of a specialized organic matrix that can form microcrystalline particles in aqueous medium with the aid of surfactants. In matrix's microcrystalline state, the triplet excited states of luminescent dopant within the matrix can be protected to exhibit room‐temperature afterglow. Under sonication, matrix's microcrystalline structure can be disrupted and consequently the triplet excited states of luminescent dopants lose protection to show afterglow quenching. To the best of the authors' knowledge, this study represents the first report of sonication‐responsive afterglow materials in aqueous medium, which show promising biomedical applications. [ABSTRACT FROM AUTHOR]

Metal‐free organic triplet emitters are an emerging class of organic semiconducting material. Among them, molecules with tunable emission responsive to environmental stimuli have shown great potential in solid‐state lighting, sensors, and anti‐counterfeiting systems. Here, a novel excited‐state intramolecular proton transfer (ESIPT) system is proposed showing the activation of thermally activated delayed fluorescence (TADF) or room‐temperature phosphorescence (RTP) simultaneously from both keto and enol tautomers. The prototype ESIPT triplet emitters exhibit up to 50% delayed emission quantum yield. Their enol–keto tautomerization can be switched by controlling the matrix acidity in doped polymer films. Taking advantage of these unique properties, "on‐off" switchable triplet emission systems controlled by acid vapor annealing, as well as photopatterning systems capable of generating facile and high‐contrast emissive patterns, are devised. [ABSTRACT FROM AUTHOR]

Organic phosphors exhibiting room‐temperature phosphorescence (RTP) in amorphous phase are good candidates for optoelectronic and biomedical applications. In this proof‐of‐concept work, a rational strategy to activate wide‐color ranged and persistent RTP from amorphous films by embedding electron‐rich organic phosphor into electron‐deficient matrix polyacrylonitrile (PAN) is presented. Through tailoring noncovalent interactions between the electron‐deficient PAN matrix and electron‐rich organic phosphors, an ultralong lifetime of 968.1 ms is obtained for doped film TBB‐6OMe@PAN. Control experiments conducted on the polymers polymethyl methacrylate (PMMA) and polystyrene (PS) without electron‐withdrawing groups, and organic phosphors containing electron‐withdrawing groups indicate that the persistent RTP of doped films may be triggered by strong electrostatic interactions between electron‐deficient PAN and electron‐rich organic phosphor. Further theoretical calculations including electrostatic potential distributions, binding energies, and energy decomposing analysis demonstrate that both electrostatic and dispersion interactions between electron‐deficient PAN and electron‐rich organic phosphor are responsible for the activation of persistent RTP of doped films. In addition, the doped film TBB‐6OMe@PAN still maintains brightness even after soaking in water for 12 weeks. This excellent water resistance not only is favorable for future applications but also demonstrates an advantage of electrostatic and dispersion interactions over hydrogen bonding interactions. [ABSTRACT FROM AUTHOR]

Recently, a remarkable advance has been made for metal‐free room‐temperature phosphorescence (RTP) crystals with high phosphorescence quantum yield. However, amorphous, especially heavy‐atom‐free, RTP materials still suffer from low quantum yield due to the transition‐forbidden character of phosphorescence and the relatively poor suppression of nonradiative transition in amorphous materials. In this study, a series of single‐benzene structure‐based high intersystem crossing yield phosphor is obtained. After embedding into polyvinyl alcohol matrix, all these phosphor exhibits efficient phosphorescence emission (ФP, up to 44.0%). Besides, photo‐switchable phosphorescence emission can be obtained by doping these molecules into a polymethyl methacrylate (PMMA) matrix. The phosphorescence can be gradually switched on by consuming the residual oxygen in the PMMA matrix under continuous UV light irradiation. Furthermore, the phosphorescence will be spontaneously switched off under ambient conditions. Taking advantage of the photoactivation character, this material has potential in information storage and anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

Abstract: Herein, a simple aza‐aromatic compound dibenzo[a,c]phenazine (DPPZ), which exhibits single‐molecule white light with a ternary emission, consisting of simultaneous fluorescence (S1→S0) and dual room‐temperature phosphorescence (RTP, T2→S0 and T1→S0) is reported. The Commission Internationale de l' Éclairage coordinates of DPPZ powder are (0.28, 0.33). To everyone's knowledge, this is the first case to achieve single‐molecule white emission with ternary emission of fluorescence and dual RTP. This finding provides a prototype strategy to realize low‐cost, stable pure organic single‐molecule white light emission with three standard primary colors through further precise modulation of excited states. [ABSTRACT FROM AUTHOR]

Traditional long‐persistent luminescence (LPL) materials, which are based on inorganic systems containing rare elements and with preparation temperatures of at least 1000 °C, exhibit afterglow times of more than 10 h and can be tuned for different applications. However, the development of this field is hindered due to the large thermal energy consumption and the need for nonrenewable resources. Thus, the development of a "green" design and preparation of LPL materials is of some importance. A doped‐crystalline material based on two metal‐free organic small molecules is easily prepared through ultrasonic crystallization at room temperature. It has a high‐quality, single‐crystalline structure, and visible LPL performance with a duration of more than 6 s upon low‐energy photoexcitation. A green, flexible, and convenient screen‐printing technology for controllable pattern anticounterfeiting is then developed from this purely organic material, which improves the prospects for commercial utilization in the future. [ABSTRACT FROM AUTHOR]

In article number 1807599, Dongpeng Yan and Bo Zhou describe the energy transfer that occurs between a thermally activated delayed fluorescent molecule (melamine) and room temperature phosphorescent molecule (isophtalic acid) in their co‐crystal, which achieves a highly enhanced photoemission lifetime (2 seconds). [ABSTRACT FROM AUTHOR]

Molecular room‐temperature phosphorescent (RTP) materials with long‐lived excited states have attracted widespread attention in the fields of optical imaging, displays, and sensors. However, accessing ultralong RTP systems remains challenging and examples are still limited to date. Herein, a thermally activated delayed fluorescence (TADF)‐assisted energy transfer route for the enhancement of persistent luminescence with an RTP lifetime as high as 2 s, which is higher than that of most state‐of‐the‐art RTP materials, is proposed. The energy transfer donor and acceptor species are based on the TADF and RTP molecules, which can be self‐assembled into two‐component ionic salts via hydrogen‐bonding interactions. Both theoretical and experimental studies illustrate the occurrence of effective Förster resonance energy transfer (FRET) between donor and acceptor molecules with an energy transfer efficiency as high as 76%. Moreover, the potential for application of the donor–acceptor cocrystallized materials toward information security and personal identification systems is demonstrated, benefitting from their varied afterglow lifetimes and easy recognition in the darkness. Therefore, the work described in this study not only provides a TADF‐assisted FRET strategy toward the construction of ultralong RTP, but also yields hydrogen‐bonding‐assembled two‐component molecular crystals for potential encryption and anti‐counterfeiting applications. Two‐component co‐crystallized materials formed by melamine and isophthalic acid through hydrogen‐bonding exhibit ultralong room temperature phosphorescence (RTP) with a lifetime of 2 seconds, which has been further designed for encryption and finger identification. Effective energy transfer occurs between melamine (thermally activated delayed fluorescence molecule) and isophtalic acid, like carriers in traps triggered by thermal excitation in inorganic persistent phosphors. [ABSTRACT FROM AUTHOR]

Polymer‐based materials have evoked increasing attention in the research field of room‐temperature phosphorescence (RTP) because they can not only possess fantastic properties such as good flexibility, easy processing, low cost, high thermal stability and so forth, but also serve as rigid matrices to suppress the nonradiative decay process and thus contribute to phosphorescence emission at room temperature. This Review outlines the development of RTP in organic polymer‐based materials from the perspective of nondoped and doped polymer systems, containing the detailed photophysical properties, luminescent mechanisms and their applications. The conclusion and outlook are presented to point out the advances and challenges for further study of polymer‐based metal‐free RTP materials. Here, the perspective of material categories in polymer‐based metal‐free room‐temperature phosphorescence during the past decades is presented. Detailed photophysical properties, luminescent mechanisms, and the related applications in hypoxia imaging, sensing, encryption ink, and lifetime‐encoding are summarized. The current challenges are also analyzed and highlighted. [ABSTRACT FROM AUTHOR]