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Abstract Recently, biomass‐derived carbon dots (CDs) have attracted considerable attention in high‐technology fields due to their prominent merits, including brilliant luminescence, superior biocompatibility, and low toxicity. However, most of the biomass‐derived CDs only show bright fluorescence in diluted solution because of aggregation‐induced quenching effect, hence cannot exhibit solid‐state long‐lived room‐temperature phosphorescence (RTP) in ambient conditions. Herein, matrix‐free solid‐state RTP with an average lifetime of 0.50 s is realized in the CDs synthesized by one‐pot hydrothermal treatment of duck feather waste powder. To further enhance RTP lifetime, hydrogen bonding is introduced by employing polyols like polyvinyl alcohol (PVA) and phytic acid (PA), and a bimodal luminescent CDs/PVA/PA ink is exploited by mixing the CDs and polyols. Astonishingly, the CDs/PVA/PA ink screen‐printed onto cellulosic substrates exhibits unprecedented green RTP with average lifetime of up to 1.97 s, and the afterglow lasts for more than 14 s after removing UV lamp. Such improvement on RTP is proposed to the populated excited triplet excitons stabilized by rigid chains. Furthermore, the CDs/PVA/PA ink demonstrates excellent potential in anticounterfeiting and information encryption. To the best of the authors' knowledge, this work is the first successful attempt to fabricate matrix‐free ultra‐long RTP CDs by reclamation of the feather wastes for environmental sustainability.

Herein we employ density functional theory (DFT) and linear response time-dependent density functional theory (LR-TDDFT) together with our own n-layered integrated molecular orbital and molecular mechanics (ONIOM)-based quantum mechanical/molecular mechanics (QM/MM) methods to study the room-temperature phosphorescent (RTP) micro-mechanism of several benzonitrile-carbazole (CzBz-X) molecules (i.e. CzBz-H, CzBz-F, CzBz-Cl, CzBz-Br) in liquid and solid state. Based on the calculated the ground- and excited-state geometric and electronic structures, the absorption and emission spectra are simulated and agreed well with previous experimental observation. The intersystem crossing (ISC) rate constants of S1 -> T1 obtained by the formula derived from the Fermi golden rule are small in liquid state, while the ISC rate constants are comparable to the relative radiative rate constants of S1 ->S0 in solid state. Molecular vibrations are restricted in solid state, which lead to the decrease of reorganization energies and Huang-Rhys factors, and the increase of ISC rate constants. Both the heavy-atom effect and aggregation effect play important roles in improving the RTP performance in CzBz-X compounds. Through quantum chemistry calculations, the present work not only elucidates the RTP mechanism and the significance of heavy-atom and aggregation effects in CzBz-X, but also provides new insights for designing novel RTP materials.

The long-lived room-temperature phosphorescence (RTP) originating from thiophene boronate polyvinyl alcohol (PVA) has enabled the creation of metal-ion-responsive RTP films doped with spirolactam ring-containing rhodamine 6G (1). In this study, RTP-active PVA films, namely, TDB@PVA and ATB@PVA, were prepared through boronate esterification of thiophene-2,5-diboronic acid (TDB) and 5-acetylthiophene-2-boronic acid (ATB) with the diol units of PVA. The delayed emission properties were evaluated, revealing an emission band at 477 nm with a turquoise afterglow for TDB@PVA and at 510 nm with a green afterglow for ATB@PVA after UV light irradiation ceased. The photophysical properties were assessed using TD-DFT and DFT calculations at the B3LYP/cc-pVDZ level. N-(rhodamine-6G)lactam dye with a salicylimine unit (1) was doped into the RTP-based PVA films, producing a multicolored afterglow upon the addition of metal ions. This phenomenon is explained by a triplet-to-singlet Förster-type resonance energy transfer process from the cross-linked thiophene boronate in PVA to the metal-ion-activated colored form of 1. This photophysical feature finds applicability in encryption techniques. Notably, the reversible metal-ligand coordination of 1 in the PVA system enabled a write/erase information process.

Abstract Polymeric room‐temperature phosphorescence (RTP) materials especially multicolor RTP systems hold great promise in concrete applications. A key feature in these applications is a triplet charge transfer transition. Aromatic electron donors and electron acceptors are often essential to ensure persistent RTP. There is much interest in fabricating non‐aromatic charge‐transfer‐mediated RTP materials and it still remains a formidable challenge to achieve color‐tunable RTP via charge transfer. Herein, a charge‐transfer‐mediated RTP material by embedding quinoline derivatives within a non‐aromatic polymer matrix such as polyacrylamide (PAM) or polyvinyl alcohol (PVA) is developed. Through‐space charge transfer (TSCT) is achieved upon alkali‐ or heat treatment to realize a long phosphorescence lifetime of up to 629.90 ms, high phosphorescence quantum yield of up to 20.51%, and a green‐to‐blue afterglow for more than 20 s at room temperature. This color‐tunable RTP emerges from a nonaromatic polymer to single phosphor charge transfer that has rarely been reported before. This finding suggests that an effective and simple approach can deliver new color‐tunable RTP materials for applications including multicolor display, information encryption, and gas detection.

Abstract Avoiding the tedious process of crystal cultivation and directly obtaining organic crystals with desirable phosphorescent performance is of great significance for studying their structure and properties. Herein, a set of benzophenone‐cored phosphors with bright green afterglow are obtained on a large scale through in‐situ generation via an end‐capping strategy to suppress non‐radiative triplet excitons and reinforce the intermolecular interactions. The ordered arrangement of phosphors with alkyl‐cyano groups as regulators is crucial for the enhancement of room‐temperature phosphorescence (RTP) emission, which has been further verified by the attenuated lifetimes in isolated states through the formation of inclusion complexes upon binding with pillar[5]arenes. Moreover, the hierarchical interactions of phosphors, including hydrogen bonding, π‐π stacking interactions, and van der Waals forces, are quantified by crystal structures and theoretical calculation to deeply interpret the origins of RTP emission. With this study, we provide a potential strategy for the direct acquisition of crystalline organic phosphors and modulation of RTP.

Abstract Organic scintillators have recently gained considerable attentions in X‐ray detection for their potential applications in biomedical radiograph and security inspection. However, the weak X‐ray absorption and/or inefficient exciton utilization have limited the development and commercialization of organic scintillators. Currently, high‐performance X‐ray organic scintillators are scarce and organic scintillators with dual triplet‐harvesting channels have not been explored before. Here, we develop several proof‐of‐concept sulfone‐based organic molecules, C1–C7, using different alkoxy chains to manipulate molecular packing mode. These materials exhibit dual triplet‐harvesting channels of thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP) in aggregated state. Inspiringly, these molecules display distinct radioluminescence under the X‐ray stimulation. Among them, C6 behaves the highest light yield of 16,558 photons MeV−1. Moreover, clear X‐ray images are demonstrated in both aggregated state and single‐molecule level. High spatial resolutions of 15.0 and 10.6 line pairs per millimeter (lp mm−1) are achieved for rigid and flexible scintillator screens, exceeding most reported organic and conventional inorganic scintillators. These results highlight the great potential of organic molecules with TADF and RTP nature for efficient X‐ray scintillation and imaging.

Abstract In order to improve the performance of organic luminescent materials, lots of studies have been carried out at the molecular level. However, these materials are mostly applied as solids or aggregates in practical applications, in which the relationship between aggregation structure and luminescent property should be paid more attention. Here, we obtained five phenothiazine 5,5‐dioxide (O‐PTZ) derivatives with distinct molecular conformations by rational design of chemical structures, and systematically studied their room‐temperature phosphorescence (RTP) effect in solid state. It was found that O‐PTZ dimers with quasi‐equatorial (eq) conformation tended to show stronger π‐π interaction than quasi‐axial (ax) conformers in crystal state, which was more conducive to the generation of RTP. Based on this result, a multi‐level structural model of organic solids was proposed to draw the relationship between aggregation structure and RTP effect, just like the research for the structure‐property relationship of proteins. Using this structural model as the guide, boosted RTP efficiency from 1% to 20% was successfully achieved in the corresponding host‐guest doping system, showing its wide applicability.

Recently, purely organic room-temperature phosphorescence (RTP) from guest-host-doped systems has grown exponentially due to their high modulation flexibility. Benzophenone has been found as a preferred host matrix thanks to its low melting point, minimal biological toxicity, remarkable stability, and cost-effectiveness. However, the precise role of benzophenone remains elusive and has been debated within the scientific community concerning mechanistic elucidations. Here, five indole derivatives were designed and synthesized as guest molecules while retaining benzophenone as the host to construct doped materials exhibiting outstanding RTP properties. Our experimental findings unequivocally establish that the host benzophenone initially absorbs excitation energy, subsequently intersystem crossing into triplet exciton, facilitating the exciton transfer to guest molecule through the triplet energy transfer and culminating in guest RTP emission. Mechanistic investigation corroborates the superiority of benzophenone in possessing a large spin-orbit coupling constant and quantitatively triplet energy transfer. Collectively, this work provides compelling evidence deciphering energy transfer between host and guest entities for the manifestation of phosphorescence performance in benzophenone-hosted doped materials.

Narrowband afterglow materials display interesting functions in high-quality anti-counterfeiting and multiplexed bioimaging. However, there is still a limited exploration of these afterglow materials, especially for those with a full width at half maxima (FWHM) around 30 nm. Here, we report the fabrication of narrowband organic/inorganic hybrid afterglow materials via energy transfer technology. Coronene (Cor) with a long phosphorescence feature and broad phosphorescence band is selected as the donor for energy transfer, and inorganic quantum dots (QDs) of CdSe/ZnS with a narrowband emission are used as acceptors. Upon doping into the organic matrix, the resultant three-component materials exhibit a narrowband afterglow with an afterglow lifetime of approximately 3.4 s and an FWHM of 31 nm. The afterglow wavelength of the afterglow materials can be controlled by the QDs. This work based on organic/inorganic hybrids provides a facile approach for developing multicolor and narrowband afterglow materials, as well as opens a new way for expanding the features of organic afterglow for multifunctional applications. It is expected to rely on narrowband afterglow emitters to solve the “spectrum congestion” problem of high-density information storage in optical anti-counterfeiting and information encryption.

Abstract Afterglow room‐temperature emission that is independent of autofluorescence after ceasing excitation is a promising technology for state‐of‐the‐art bioimaging and security devices. However, the low brightness of the afterglow emission is a current limitation for using such materials in a variety of applications. Herein, the continuous formation of condensed triplet excitons for brighter afterglow room‐temperature phosphorescence is reported. (S)‐(‐)‐2,2′‐Bis(diphenylphosphino)‐1,1′‐binaphthyl ((S)‐BINAP) incorporated in a crystalline host lattice showed bright green afterglow room‐temperature phosphorescence under strong excitation. The small triplet–triplet absorption cross‐section of (S)‐BINAP in the whole range of visible wavelengths greatly suppressed the deactivation caused by Förster resonance energy transfer from excited states of (S)‐BINAP to the accumulated triplet excitons of (S)‐BINAP under strong continuous excitation. The steady–state concentration of the triplet excitons for (S)‐BINAP reached 2.3 × 10−2 M, producing a bright afterglow. Owing to the brighter afterglow, afterglow detection using individual particles with sizes approaching the diffraction limit in aqueous conditions and irradiance‐dependent anticounterfeiting can be achieved.

Abstract Developing smart room‐temperature phosphorescence (RTP) materials with facile and efficient strategies have attracted increasing attention. Herein, tunable RTP materials with two phosphorescent sources and stepwise enhanced phosphorescence in water are obtained through an in‐situ self‐assembly strategy based on the sensitization of phosphors by trimesic acid (TMA) through simple doping and the rigidification of phosphors by hydrogen‐bonded organic frameworks (HOFs). As expected, doped TMA+phosphors simultaneously promote the RTP emission of phosphors and maintain TMA phosphorescence. In‐situ assembled HOF(MA‐TMA)@phosphors facilitate smart RTP emission in water due to the coexistence of phosphorescent HOF(MA‐TMA) host and phosphors guest. Additionally, such RTP materials with good processability demonstrate the application potential in information security, benefitting from their varied afterglow lifetimes and easy luminous recognition in the darkness. This work will inspire the design of dual phosphorescent source RTP systems and provide new strategies for the development of smart RTP materials in water.

Abstract Room‐temperature phosphorescence (RTP) of purely organic materials is easily quenched with unexpected purposes because the excited triplet state is extremely susceptible to external stimuli. How to stabilize the RTP property of purely organic luminogens is still challenging and considered as the bottleneck in the further advancement of the bottom‐up approach. Here, we describe a gated strategy that can effectively harness RTP by employing complexation/dissociation with proton. Due to the order‐disorder transition orientation of intermolecular packing, the RTP of organic molecules 2,4,6‐tris(4′‐bromo‐[1,1′‐biphenyl]‐4‐yl)‐1,3,5‐triazine (Br‐TRZ) will easily vanish upon mechanical force. Impressively, by enhancing its intramolecular charge transfer effect, the protonated Br‐TRZ stubbornly possesses an obvious RTP under external grinding, whatever in the ordered or disordered intermolecular arrangement state. Consequently, the “Lock” gate of RTP was achieved in the protonated Br‐TRZ molecule. Combined with theoretical calculation analysis, the enhanced charge transfer effect can narrow the singlet−triplet energy gap significantly, and stabilize the RTP property of triazine derivative sequentially. Furthermore, the locked RTP can be tuned via proton and counterions repeatedly and show excellent reversibility. This gated RTP concept provides an effective strategy for stabilizing the RTP emission of purely organic systems.

Abstract Inorganic boric acid (BA) is generally not considered an efficient afterglow material, and several groups have reported its extremely weak room‐temperature phosphorescence (RTP) in the blue spectral region. It is discovered that heat treatment of BA results in increased afterglow intensity (27‐fold increase) and prolonged emission lifetime (from 0.83 to 1.59 s), attributed to enhanced through‐space conjugation (TSC) of BA. The afterglow intensity of BA can be increased further (≈415 folds) by introducing p‐hydroxybenzoic acid (PHA), which contains a conjugated molecular motif, to further promote the TSC of the BA system. This combination results in the production of afterglow materials with a photoluminescence quantum yield of 83.8% and an emission lifetime of 2.01 s. In addition, a tunable multicolor afterglow in the 420–490 nm range is achieved owing to the enhancement of the RTP and thermally activated delayed fluorescence of PHA, where BA exerts a confinement effect on the guest molecules. Thus, this study demonstrates promising afterglow materials produced from extremely abundant and simple precursor materials for various applications.

As emerging carbon‐based nanomaterials, carbon dots (CDs) are widely studied with regard to their luminescent properties. CDs obtained by the bottom‐up method exhibit polymeric characteristics after crosslinking, polymerization, and incomplete carbonization processes, herein referred to as carbonized polymer dots (CPDs). In recent years, large progress has been achieved on the room‐temperature phosphorescence (RTP) properties of CPDs. The developments and synthesis strategies for RTP CPD materials are reviewed. However, less attention has been devoted to the influence of polymeric structures on RTP of CPD materials. Polymer structures are a common feature of CPD materials. The extensive polymer structures are the key factors facilitating the RTP of CPD materials. Herein, the effects of the polymer structures on the RTP emission of self‐protective CPD and matrix‐assisted CPD materials are discussed. It is considered that the polymer structures can effectively immobilize subluminophores and protect triplet excited states to facilitate the RTP emission of CPD materials. The crosslink‐enhanced emission (CEE) effect is proposed to further explain the RTP emission of CPD materials, which can provide an effective strategy to immobilize CPDs. Benefiting from CEE effect, efficient RTP can be achieved for CPD materials. The applications of CPD materials are then briefly summarized.

Abstract Metal‐free room‐temperature phosphorescence (RTP) materials are of great significance for many applications; however, they usually exhibit low efficiency and weak intensity. This article reports a new strategy for the preparation of a high‐efficiency and strong RTP materials from crystalline thermal‐annealed carbon dots (CDs) and boric acid (BA) composite (g‐t‐CD@BA) through grinding‐induced amorphous to crystallization transition. Amorphous thermal‐annealed CDs and BA composite (t‐CD@BA) is prepared following a thermal melting and super‐cooling route, where the CDs are fully dispersed in molten BA liquid and uniformly frozen in an amorphous thermal annealed BA matrix after super‐cooling to room temperature. Upon grinding treatment, the fracture and fragmentation caused by grinding promote the transformation of the high‐energy amorphous state to the lower energy crystalline counterparts. As a result, the CDs are uniformly in situ embedded in the BA crystal matrix. This method affords maximum uniform embedding of the CDs in the BA crystals, decreases nonradiative decay, and promotes intersystem crossing by restraining the free vibration of the CDs, thus producing strong RTP materials with the highest reported phosphorescence quantum yield (48%). Remarkably, RTP from g‐t‐CD@BA powder is strong enough to illuminate items with a delay time exceeding 9 s.

Abstract Currently, there is a strong drive to discover alternative materials that exhibit room‐temperature phosphorescence (RTP) for displays, bioimaging, and data security. Ideally, these materials should be nontoxic, cheap, and possess controllable photoluminescent properties. Carbon dots (CDs) possess each of these characteristics, but to date, less attention has been paid to their RTP mechanism. Herein, we synthesized a series of CDs by self‐crosslinking and carbonization of precursor. The resultant CDs were luminescent and exhibited a bright, micro‐second afterglow lifetime. To increase the RTP, a second microwave processing step was used to coat the CDs with polyvinyl alcohol (PVA), polyacrylamide (PAM), or tetraethyl orthosilicate (TEOS), producing CDs@PVA, CDs@PAM, and CDs@TEOS composites. The core–shell structure acted to enhance crosslinking at the surface of the CDs to boost the RTP, creating abundant energy levels for intersystem crossover. In situ X‐ray photoelectron spectroscopy verified electron transfer during luminescence. Finally, we present a design rule that can be used to tune the quantum yields and RTP lifetime of CDs, based on the effective stabilization of triplet excited states through the extent and strength of cross‐linking. This simple strategy provides a flexible route for guiding the further development of CDs with tailored RTP properties for various applications.

Abstract Preparation of non‐conjugated luminescent polymers (NCLPs) with excellent cluster luminescence (CL) performance is of great significance for scientific and industrious applications, and yet improving the performance of NCLPs through proper structural design is still a huge challenge. Herein, we report a non‐conjugated ionized polymeric system consisting of (−)‐camphorsulfonic acid ((−)‐CSA) and poly(2‐vinylpyridine) (P2VP). These acid‐base complexes exhibit typical excitation‐dependent fluorescence and room‐temperature phosphorescence (RTP) with a lifetime up to 364 ms. We discover that changing the stereoregularity from atactic to isotactic significantly improves the CL performance of the complex. It (1) broadens the fluorescence emission spectra to cover the entire visible region, (2) enhances the fluorescence emission intensity at long wavelength beyond 500 nm, (3) enhances the phosphorescence intensity, and (4) extends the phosphorescence lifetime. Systematical experimental characterization and molecular dynamics simulation unravel the key role of stereoregularity in determining the formation of different pyridine aggregates that strongly influence the CL performance. Moreover, the different luminescence shows great potential in excitation divided information display and time‐resolved encrypted display. This work not only points to a new direction for developing NCLPs with excellent performance, but also broadens the applications of NCLPs materials.

Abstract Purely organic room‐temperature phosphorescence (RTP) materials generally exhibit low phosphorescence quantum yield (ϕP) and long phosphorescence lifetime (τP) due to the theoretically spin‐forbidden triplet state. Herein, by introducing a donor–acceptor (D–A) skeleton with a phenoxaselenine donor, three nonaromatic amine donor containing compounds with high ϕP and short τP in amorphous films are developed. Besides the enhanced spin–orbit coupling (SOC) by the heavy‐atom effect of selenium, the D–A skeleton which facilitates orbital angular momentum change can further boost SOC, and severe nonradiative energy dissipation is also suppressed by the rigid molecular structure. Consequently, a record‐high external quantum efficiency of 19.5% are achieved for the RTP organic light‐emitting diode (OLED) based on 2‐(phenoxaselenin‐3‐yl)‐4,6‐diphenyl‐1,3,5‐triazine (PXSeDRZ). Moreover, voltage‐dependent color‐tunable emission and single‐molecule white emission are also realized. These results shed light on the broad prospects of purely organic phosphorescence materials as highly efficient OLED emitters especially for potential charming lighting applications.

Abstract Persistent luminescence has attracted great attention due to the unique applications in molecular imaging, photodynamic therapy, and information storage, among many others. However, tuning the dynamic persistent luminescence through molecular design and materials engineering remains a challenge. In this work, the first example of excitation‐dependent persistent luminescence in a reverse mode for smart optical materials through tailoring the excited‐state proton transfer process of metal cytosine halide hybrids is reported. This approach enables ultralong phosphorescence and thermally activated delayed fluorescence emission colors highly tuned by modulation of excitation wavelength, time evolution, and temperature, which realize multi‐mode dynamic color adjustment from green to blue or cyan to yellow‐green. At the single crystal level, the 2D excitation/space/time‐resolved optical waveguides with triple color conversion have been constructed on the organic‐metal halide microsheets, which represent a new strategy for multi‐dimensional information encryption and optical logic gate applications.

Abstract Despite ongoing research into photocontrolled supramolecular switches, reversible photoswitching between room‐temperature phosphorescence (RTP) and delayed fluorescence is rare in the aqueous phase. Herein, an efficient RTP‐fluorescence switch based on a cascaded supramolecular assembly is reported, which is constructed using a 6‐bromoisoquinoline derivative (G3), cucurbit[7]uril (CB[7]), sulfonatocalix[4]arene (SC4A4), and a photochromic spiropyran (SP) derivative. Benefiting from the confinement effect of CB[7], initial complexation with CB[7] arouses an emerging RTP signal at 540 nm for G3. This structure subsequently coassembles with amphiphilic SC4A4 to form tight spherical nanoparticles, thereby further facilitating RTP emission (≈12 times) in addition to a prolonged lifetime (i.e., 1.80 ms c.f., 50.1 µs). Interestingly, following cascaded assembly with a photocontrolled energy acceptor (i.e., SP), the efficient light‐driven RTP energy transfer occurs when SP is transformed to its fluorescent merocyanine (MC) state. Ultimately, this endows the final system with an excellent RTP–fluorescence photoswitching property accompanied by multicolor tunable long‐lived emission. Moreover, this switching process can be reversibly modulated over multiple cycles under alternating UV and visible photoirradiation. Finally, the prepared switch is successfully applied to photocontrolled multicolor cell labeling to offer a new approach for the design and fabrication of novel advanced light‐responsive RTP materials in aqueous environments.

The development of organic materials displaying room-temperature phosphorescence is a research field that has attracted more and more attention in the last years. Most studies focus on designing or optimizing emitter molecules to increase the phosphorescent performance in host:emitter systems. Rarely, the overall thin-film preparation routines are compared with respect to their triplet-state luminescence yield. Herein, different film preparation techniques are investigated using the very same emitter molecule. A variation of host polymer, post-annealing temperature, and fabrication procedure is evaluated with respect to the obtained phosphorescent lifetime, photoluminescent quantum yield, and phosphorescence-to-luminescence ratio. This study elaborates the importance of different film preparation techniques and gathers a concise set of data which is helpful to anyone optimizing the phosphorescence of a particular system.

Summary: Room-temperature phosphorescence (RTP) has received extensive attention in recent years due to its various potential applications. Pure organic RTP materials may overcome the shortcomings of harsh preparation conditions and high toxicity associated with metal complexes and rare-earth-containing materials. Although crystallization strategies can yield rigid environments isolated from oxygen, its inferior processability can significantly limit the corresponding practical applications. Considering their flexibility, stretchability, processability, and thermal stability with flexible long chains and intertwined structures, polymers are an ideal material for achieving RTP and realizing practical applications. In this review, we summarize the latest progress in polymer-based RTP materials, elaborating on two strategies of chemical bonding and physical blending. In the last part of the review, challenges and perspectives of amorphous polymers are proposed to improve RTP performance and develop new applications.

Abstract Transforming carbon dots (CDs) fluorescent materials into smart materials with complex functions is a topic of great interest to nanoscience. However, designing CDs with regulating fluorescence/phosphorescence that can be visually monitored with the environment changes in real‐time remains a challenge. Here, a very simple strategy, one‐step solvent‐free catalytic assistant strategy, which is low cost, facile, environment‐friendly, and high throughput, is put forward. Hydrogen bond is used to manipulate nanostructure of CDs, and the obtained carbon dots (M‐CDs) show a series of attractive properties including matrix‐free room‐temperature phosphorescence, time‐dependent fluorescence, and near‐infrared emissive characteristics. Different from the traditional aggregation caused quenching or aggregation‐induced emission fluorescent materials, M‐CDs exhibit unprecedented and unique dispersion induced redshift fluorescence phenomenon, promoting the studies of fluorescence from static to dynamic. The causes of this phenomenon are further analyzed in detail. As a kind of intelligent fluorescent materials, this new designed CDs greatly enrich the basic recognition of CDs by illustrating the relationship between redshift fluorescence behaviors and the dispersion states, and may provide with an opportunity for solid‐state fluorescent materials, anti‐counterfeiting, cellular imaging, and hopefully many others.

Modulating the stimulus-responsiveness of a luminescent crystal is challenging owing to the complex interdependent nature of its controlling factors, such as molecular structure, molecular conformation, crystal packing, optical properties, and amorphization behavior. Herein, we demonstrate a halogen-exchange approach that disentangles this problem, thereby realizing the modulation of room-temperature phosphorescence-to-phosphorescence mechanochromism. Replacing the bromine atoms in a brominated thienyl diketone with chlorine atoms afforded isostructural crystals; i.e., molecules with different halogen atoms exhibited the same molecular conformation and crystal packing. Consequently, amorphization behavior toward mechanical stimulation was also the same, and the phosphorescence of amorphous states originated from the same conformer of each diketone. In contrast, the phosphorescence properties of each conformer were modulated differently, which is ascribable to heavy atom effects, resulting in the modulation of the mechanochromism. Thus, halogen exchange is a promising approach for modulating the stimulus-responsive photofunctions of crystals involving spin-forbidden processes.

Abstract Ultralong room‐temperature phosphorescence (RTP) is highly useful for information encryption, organic electronics, bioelectronics, etc. However, the preparation of related metal‐free materials with multiple colors across the full spectrum remains a major challenge. Herein, a facile method is developed to fabricate boron‐doped carbon dot (B‐CD) composites with full‐color long lifetime RTP continuously tailorable in the range of 466–638 nm simply by pyrolysis of the citric acid and boric acid precursors with various mass ratios at different temperatures. This leads to the formation of luminescent B‐CD centers in a rigid polycrystalline B2O3 matrix, which effectively stabilizes the triplet excited states of B‐CDs. Thus, the composites become phosphorescent over a relatively long period (5–12 s) after the removal of the irradiation source. Meanwhile, the increased particle size and oxidation degree of B‐CDs obtained at larger citric acid feeding or higher pyrolysis temperature continuously shift the phosphorescence from blue to red. Due to the formation of multiple luminescence centers, the RTP can also be finely modulated by the excitation wavelength. The resulting B‐CD composites with highly tunable long lifetime RTP further allow a variety of distinctive applications in multidimensional encryption handily utilizing space, time, and color variations.

AIE polymers have been extensively researched in the fields of OLEDs, sensing, and cancer treatment since its first report in 2003, which have achieved numerous breakthroughs during the years. In comparison with small molecules, it can simultaneously combine the unique advantages of AIE materials and the polymer itself, to further enhance their corresponding photophysical performances. In this review, we enumerate and discuss the common construction strategies of AIE-active polymers and summarize the progress of research on polymerization enhancing luminescence, photosensitization, and room-temperature phosphorescence (RTP) with their related applications in chemo/bio-sensing and therapy. To conclude, we also discuss current challenges and prospects of the field for future development.

Understanding the local triplet (3LE), charge transfer triplet (3CT), and charge transfer singlet (1CT) is of great importance in designing thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP) materials for their use in organic light‐emitting devices (OLEDs), sensing, and bioimaging. Herein, two phenothiazine–quinoline conjugates (PTzQ1, PTzQ2) in which the donor (PTz) and acceptor (Q1, Q2) parts are held in near‐orthogonal orientation that gives rise to spatial separation of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are reported. Photophysical studies of both conjugates along with their individual components (PTz, Q1, Q2) show that TADF occurs via reverse intersystem crossing (rISC) from the upper‐level local triplet (3LE) to lower‐level singlet 1CT mediated by vibronic coupling between 3LE and 3CT, whereas RTP is realized from 3LE. It is found that all three excited states are close in energy, 0.16–0.19 eV (3LE−1CT), 0.02–0.03 eV (1CT−3CT), and 0.14–0.16 eV (3LE−3CT) with the order of 3LE > 1CT > 3CT. Both conjugates exhibit a high rate constant of rISC (krISC, 7.9–9.7 × 105 s−1), resulting in external quantum efficiency (EQE) values of ≈4.7% (solution processed) with emission from both RTP and TADF components.

Purely organic circularly polarized luminescent (CPL) materials have attracted much attention owing to their fascinating photophysical properties and potential applications in the fields of optical data storage, smart sensors/probers, high‐resolution 3D display, and so on. With the development of photophysical science, the emergence of some novel emission phenomena, such as thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP), have become hot topics and enriched CPL materials. However, there is no systematic review that summarizes the recent development of chiral small organic molecules (SOMs) with TADF and RTP characters. In this minireview, the progress of purely organic CPL materials in the last 5 years is reviewed by categorizing into chiral fluorescence molecules, chiral TADF molecules, and chiral RTP molecules. Furthermore, the design strategy of chiral TADF emitters is discussed and the correlation between chirality and RTP properties is concluded.

Organic room‐temperature phosphorescence (RTP) has attracted tremendous attention in recent years due to its potential utility in combination with artificial soft materials. Herein, a room‐temperature‐phosphorescent hybrid xerogel held together by electrostatic and host–guest interactions is reported. The xerogel is constructed by noncovalent complexation of 7‐[6‐deoxy‐6‐(2‐sulfonic)]‐β‐cyclodextrin (SCD) with the phosphor bromophenyl‐methyl‐pyridinium chloride (PYCl) and in situ incorporation of the anionic SCD⊃PYCl complex into a cationic amino clay (AC) via electrostatic interactions. The resulting xerogel, designated AC/SCD⊃PYCl, has a network structure that can suppress vibrational and nonradiative relaxation of the phosphor, leading to green RTP emission as well as good fluorescence–phosphorescence dual emission. Notably, the intensity of the xerogel RTP varies with humidity and can be switched on and off repeatedly, which indicates that the xerogel has potential utility as an organic light‐emitting humidity‐sensing material.

Summary: The transfer of molecular machine technology into aggregated states is a key step for the realization of many potential applications. Here we report three organic luminescent agents, CzS-o-py, CzS-m-py, and CzS-p-py, that can adjust organic room-temperature phosphorescence (RTP) via orderly stimulus-responsive molecular motion in the crystal. Careful analysis of the single-crystal structure before and after ordered molecular motion, coupled with theoretical calculations, reveals the effective intermolecular charge transfer generated by the dense packing mode to be responsible for the RTP effect. Accordingly, a dual anti-counterfeiting application is successfully implemented, exploiting the RTP effect of the stimulus response. The introduction of molecular mechanical technology may provide a strategy for the molecular design, internal mechanism exploration, and practical application of RTP luminescent agents.

Pure organic room temperature phosphorescence (RTP) materials have attracted extensive attention in recent years due to their unique characteristics, such as flexible design method, low toxicity, low cost, as well as the ease of production at scale. The involvement of triplet state and direct radiative transition from the triplet state show that RTP materials have great potential as a new generation emitter in organic light-emitting diodes (OLEDs). Based on the mechanism of phosphorescence, various methods have been developed to achieve RTP emissions in the crystal state. However, the observation of RTP in the thin film state is much more difficult to achieve because of the lower degree of rigidity and suppression of the non-radiative transition. In this mini-review, molecular design strategies developed to achieve RTP emissions and their application in OLEDs are summarized and discussed. The conclusion and outlook point to great potential as well as the challenges for the continued study of pure organic RTP materials-based OLEDs.

Gold(I) complexes are some of the most attractive materials for generating aggregation-induced emission (AIE), enabling the realization of novel light-emitting applications such as chemo-sensors, bio-sensors, cell imaging, and organic light-emitting diodes (OLEDs). In this study, we propose a rational design of luminescent gold complexes to achieve both high thermochemical stability and intense room temperature phosphorescence, which are desirable features in practical luminescent applications. Here, a series of gold(I) complexes with ligands of N-heterocyclic carbene (NHC) derivatives and/or acetylide were synthesized. Detailed characterization revealed that the incorporation of NHC ligands could increase the molecular thermochemical stability, as the decomposition temperature was increased to ~300 °C. We demonstrate that incorporation of both NHC and acetylide ligands enables us to generate gold(I) complexes exhibiting both high thermochemical stability and high room-temperature phosphorescence quantum yield (>40%) under ambient conditions. Furthermore, we modified the length of alkoxy chains at ligands, and succeeded in synthesizing a liquid crystalline gold(I) complex while maintaining the relatively high thermochemical stability and quantum yield.

Harmane has been proposed for the treatment of epilepsy, AIDS and leshmaniosis. Its room-temperature phosphorescence was induced using either AgNO3 or TlNO3, enabling absolute limits of detection of 0.12 and 2.4 ng respectively, with linear dynamic ranges extending up to 456 ng (AgNO3) and 911 ng (TlNO3). Relative standard deviations around 3% were observed for substrates containing 46 ng of harmane. Such sensitivity and precision are needed because harmane intake must be strictly controlled to achieve proper therapeutic response. Interference studies were performed using thalidomide, reserpine and yohimbine. Recovery of 104±6% was achieved using solid surface room-temperature phosphorimetry. The result was comparable to the one obtained by micellar electrokinetic chromatography.