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Hybrid metal halides have received great interests in the field of solid-state lighting technologies due to their diverse structures and excellent emission properties. In this work, we report the synthesis and characterization of four blue-emitting zero-dimensional hybrid metal halides, namely, (2HP) 2 ZnCl 2 , (2HP) 2 ZnBr 2 , (2TP) 2 ZnCl 2 , and (2TP) 2 ZnBr 2 (2HP = 2-hydroxypyridine, 2TP = pyridine-2-thiol). By changing the ligands and halides, a remarkable increase in the photoluminescence quantum yield of (2HP) 2 ZnCl 2 (44.7%) compared to (2TP) 2 ZnBr 2 (1.8%) is realized. The 2HP series features excitation-dependent emission characteristics, whereas the 2TP series does not due to the effect of a different organic ligand. Utilizing time-resolved and temperature-dependent photoluminescence spectroscopies, all four compounds exhibit both thermally activated delayed fluorescence and room-temperature phosphorescence properties. These materials have excellent ambient and thermal stabilities and are solution-processable. Our work shows the importance of carefully incorporating organic ligands with the appropriate inorganic metal center to achieve tunable emission properties.

Purely organic room temperature phosphorescence (RTP) materials are a new kind of triplet emitter, which can harvest both singlet and triplet excitons in theory, thus showing great application potential for organic light-emitting diodes (OLEDs). However, nondoped OLEDs based on RTP emitters have been rarely explored owing to challenges in realizing efficient phosphorescence in single-component systems. Herein, three donor-acceptor-type luminogens were designed and synthesized in which phenothiazine, with different oxidation degrees, acted as the electron donor and acetophenone as the acceptor. The adjustable oxidation states of phenothiazine enabled the modulation of excited states, facilitating the transition from dual RTP and thermally activated delayed fluorescence emissions to pure RTP. A nondoped OLED device was then fabricated based on the pure RTP emitter, achieving a high exciton utilization efficiency of 86%, clearly demonstrating the enhancement of electroluminescence performance through RTP properties.

Scintillators have attracted significant attention due to their wide-ranging applications in both industrial and medical fields. However, one of the ongoing challenges is the efficient utilization of triplet excitons to achieve high radioluminescence efficiency. Here, a series of purely organic phosphors is presented for X-ray scintillation, employing a combined rigid and flexible host-guest doping strategy. The doped crystals exhibit a remarkable maximum phosphorescence efficiency of 99.4% under UV excitation. Furthermore, upon X-ray irradiation, the radioluminescence intensities of the doped phosphors are markedly higher compared to their single-component crystal counterparts. Through systematic investigations, it is demonstrated the crucial role of confining isolated chromophores in enhancing scintillation efficiency. Additionally, a transparent scintillator screen fabricated with the doped phosphor exhibits excellent X-ray imaging performance, achieving a high spatial resolution of 18.0 lp mm -1 . This work not only offers valuable insights into suppressing non-radiative transitions of triplet excitons during scintillation but also opens a new avenue for designing highly efficient purely organic phosphorescent scintillators., (© 2024 Wiley‐VCH GmbH.)

Developing pure organic room-temperature phosphorescent (RTP) hydrogels is important for expanding the practical applications of phosphorescent materials. However, most of the reported RTP hydrogels containing aromatic phosphors suffer from short phosphorescent lifetimes, unstable underwater RTP emissions, and complex preparation processes. Herein, novel nonaromatic RTP hydrogels are prepared by using two types of non-traditional luminescent polymers, sodium alginate and a polymeric carboxylate, which are not RTP emissive or very weakly emissive in aqueous environments. The prepared hydrogels exhibit the following features: I) color-tunable RTP emissions with ultra-long lifetimes up to 451.1 ms, II) excellent anti-swelling properties and stable persistent RTP emission even after being immersed in deionized water for months, III) efficient and large-scale preparation of hydrogel fibers by wet spinning technique. Experiment results and theoretical calculations show that the stable and long-lifetime RTP emissions of the hydrogels originate from the introduction of more nonconventional chromophores which are strongly crosslinked with ionic bonding between carboxylate groups and calcium ions and enhanced through-space interactions between them. This work provides a reliable strategy for designing nonaromatic hydrogels with stable and persistent RTP., (© 2024 Wiley‐VCH GmbH.)

Aggregation-induced phosphorescence (AIP) has attracted much attention for its unique luminescent characteristics. Nevertheless, this fascinating phenomenon is rarely reported in the field of carbon dots (CDs). Herein, a simple method to prepare CDs simultaneously with dispersion-state fluorescence, aggregation-state fluorescence, and phosphorescence is presented by a one-step solvothermal process. The resultant AIP CDs (A-CDs) display a long afterglow lifetime of 0.51 s in the aggregation state, lasting about 5 s to the naked eye. The phosphorescence emission of A-CDs resulted from the rigid, protective structure due to the aggregation state. In addition, inorganic silica has been employed as a doping matrix to effectively improve phosphorescent properties (1.11 s). Benefitting from the unique luminescence feature and excellent water dispersibility, the A-CDs can be dispersed directly in water, and the phosphorescent emission could be controlled by regulating the concentration, thus enabling information encryption. [ABSTRACT FROM AUTHOR]

Realizing efficient and ultralong room‐temperature phosphorescence (RTP) is highly desirable but remains a challenge due to the inherent competition between excited state lifetime and photoluminescence quantum yield (PLQY). Herein, we report the bottom‐up self‐assembly of transparent metal–organic framework (MOF) bulk glasses exhibiting direct ultralong all‐phosphorescence (lifetime: 630.15 ms) with a PLQY of up to 75 % at ambient conditions. These macroscopic MOF glasses have high Young's modulus and hardness, which provide a rigid environment to reduce non‐radiative transitions and boost triplet excitons. Spectral technologies and theoretical calculations demonstrate the photoluminescence of MOF glasses is directly derived from the different triplet excited states, indicating the great capability for color‐tunable afterglow emission. We further developed information storage and light‐emitting devices based on the efficient and pure RTP of the fabricated MOF photonic glasses. [ABSTRACT FROM AUTHOR]

The construction of highly luminescent solid‐state materials with long‐lived afterglow through a straightforward method is promising but still a challenging task. Herein, a heat‐treatment strategy is proposed to embed levofloxacin (Lev) in the matrix of boric acid (BA) to produce a complex with a photoluminescence quantum yield of 63.8% and an emission lifetime of 0.74 s (afterglow: >5 s). Detailed investigations suggest that the unique photophysical properties of the complex are attributed to the confinement effect of BA matrix to Lev, which reduces the probability of nonradiative relaxation and activates the radiative decays to result in the promoted emission efficiency. In addition, thermally activated delayed fluorescence is also activated due to the alteration of the π transition of Lev by the formation of boron–carbon bonds. The emission color and lifetime are also modulated through controlling the synthetic conditions, which endow their applications both in light‐emitting diodes and information encryption. Thus, the present results are significant for the construction of solid‐state luminescent materials, including fluorescence and room‐temperature phosphorescence, and also provide a solid and universal theory to clarify their detailed emission profiles. [ABSTRACT FROM AUTHOR]

Pure organic crystal of N,N‐di‐methyl‐4‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)aniline (DMAB) exhibits efficient room‐temperature phosphorescence (RTP) with an emission maximum at 387 nm and a high phosphorescence efficiency of 35.2%. Significantly, DMAB shows an exceptional photo‐induced ultra‐long RTP (URTP) at 539 nm, which displays an afterglow time of 14 s in air. The two phosphorescent bands are attributed to the monomeric and aggregated RTP of DMAB, respectively. Continuous UV irradiation for ≈1 min can dramatically improve the lifetimes for both of the monomeric and aggregated phosphorescent emissions. The photo‐induced URTP can be spontaneously switched off after standing the crystal in air for 50 min, and this cyclic process has been repeated several times. The molecular packing based on multiple intermolecular noncovalent interactions is adopted in DMAB crystal, which is beneficial to RTP. Upon UV irradiation, the consumption of oxygen in the crystal matrix accounts for the distinctive photo‐induced URTP. Taking advantage of the unique photo/oxygen‐sensitive properties, DMAB crystals have been successfully utilized in oxygen sensing and anticounterfeiting. [ABSTRACT FROM AUTHOR]

A purely organic supramolecular assembly emitting three‐photon room‐temperature phosphorescence (RTP) is constructed from a macrocyclic host, cucurbit[8]uril (CB[8]), and 4‐bromophenyl pyridine salt having an alkyl chain length of 6 or 12 carbon atoms (6C and 12C, respectively). Benefiting from macrocyclic host confined guests, the encapsulation of 12C and 6C in the CB[8] cavity results in three‐photon absorption and subsequent near‐infrared (NIR) phosphorescence emission. Notably, secondary assembly with sulfonated β‐cyclodextrin (SCD) further enhances the phosphorescence emission of the multilevel supramolecular assembly. NIR‐delayed fluorescence via a light‐harvesting phosphorescent energy transfer system is achieved by adding Nile blue as a substrate. Comparison of 12C/CB[8]/SCD and 6C/CB[8]/SCD shows that a long hydrophobic layer is more conducive to stabilizing NIR‐delayed fluorescence emission. These findings indicate that multilevel supramolecular assemblies can be used for three‐photon‐excited NIR‐delayed fluorescence and RTP imaging of cancer cells, which greatly expands the biological applications of pure organic RTP materials. [ABSTRACT FROM AUTHOR]

Although different studies in carbon dots (CDs) have been reported based on heteroatom doping, most of them have focussed on the enhancement of fluorescence properties. Here we report a comparative study of both fluorescence and room‐temperature phosphorescence (RTP) of nitrogen–sulphur‐doped CDs (N–S CDs) and nitrogen–boron‐doped CDs (N–B CDs) with N‐doped CDs (N CDs). The CDs used in the study were synthesized through microwave‐assisted pyrolysis. Among the doped CDs, sulphur‐doped CDs showed a high fluorescence quantum yield. Upon irradiation, the aqueous dispersion of the CDs demonstrated blue fluorescence. Furthermore, by incorporating the CDs in a potash alum matrix, blue fluorescence, as well as green phosphorescence was observed. The phosphorescence lifetime measurements indicated that the N–S CDs exhibited a longer emission lifetime and a red‐shifted emission in contrast with other samples, which might be attributed to the presence of a greater proportion of surface states on the N–S CDs. [ABSTRACT FROM AUTHOR]

Highly efficient organic thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP) emitters for organic light‐emitting diodes (OLEDs) generally consist of a twisted donor–acceptor skeleton with aromatic amine donors. Herein, through introducing sulfur atoms into isomeric pentaphene and pentacene frameworks, we demonstrate a set of polycyclic luminophores exhibiting efficient TADF and RTP characters. The incorporation of sulfur atoms confirms a folded molecular plane, while intensifies singlet–triplet spin‐orbit coupling. Further, the isomeric effect has a significant effect on the electronic structure of excited state, giving rise to the investigated compounds tunable luminescence mechanisms of TADF and RTP. With efficient triplet harvesting ability, maximum external quantum efficiencies up to 25.1 % and 8.7 % are achieved for the corresponding TADF and RTP OLEDs, verifying the great potential of sulfur‐bridged frameworks for highly efficient devices. [ABSTRACT FROM AUTHOR]

Synergism between covalent and non‐covalent bonds is employed to fix an organic phosphor guest in a rigid inorganic framework, simulating the stiffening effect seen in the glassy state and realizing efficient and ultralong room‐temperature phosphorescence (RTP). Twelve heavy‐atom‐free composites have been obtained through introducing arylboric or arylcarboxylic acid derivatives into the inorganic boric acid matrix by solid‐phase synthesis. Owing to the stiffening effect of multiple bonds, all the composites show highly efficient and persistent RTP of guest molecules with a quantum yield ranging from 39.8 % to ca. 100 % and a lifetime up to 8.74 s, which results in a 55 s afterglow visible to the naked eye after exposure to a portable UV lamp. Interestingly, it is found that the substitution position and quantity of carboxyl in the guest have a great influence on the phosphorescent properties, and that the heavy‐atom effect is invalid in such host–guest hybrid systems. The 100 g grade composite is easily prepared because of the solvent‐free, green, and simple synthesis method. These results provide an important way for the development of RTP materials with ultrahigh quantum yield and ultralong lifetime, as well as their practical applications in the fields of anti‐counterfeiting and information storage, among others. [ABSTRACT FROM AUTHOR]

Though fluorescence‐tag‐based anti‐counterfeiting technology has distinguished itself with cost‐effective features and huge information loading capacity, the clonable decryption process of spatial‐resolved anti‐counterfeiting cannot meet the requirements for high‐security‐level anti‐counterfeiting. Herein, we demonstrate a spatial‐time‐dual‐resolved anti‐counterfeiting system based on new organic–inorganic hybrid halides BAPPZn2(ClyBr1−y)8 (BAPP=1,4‐bis(3‐ammoniopropyl)piperazinium, y=0–1) with ultra‐long room‐temperature phosphorescence (RTP). Remarkably, the afterglow lifetime can be facilely tuned by regulating the halide‐induced heavy‐atom effect and can be identified by the naked eyes or with the help of a simple machine vision system. Therefore, the short‐lived unicolor fluorescence and lasting‐time‐tunable RTP provide the prerequisites for unicolor‐time‐resolved anti‐counterfeiting, which lowers the decryption‐device requirements and further provides the design strategy of advanced portable anti‐counterfeiting technology. [ABSTRACT FROM AUTHOR]

Room‐temperature phosphorescence (RTP) originating from higher‐lying triplet excitons remains a rather rarely documented occurrence for purely organic molecular systems. Here, we report two naphthalene‐based RTP luminophores whose phosphorescence emission is enabled by radiative decay of high‐lying triplet excitons. In contrast, upon cooling the dominant phosphorescence originates from the lowest‐lying triplet excited state, which is manifested by a red‐shifted emission. Photophysical and theoretical studies reveal that the unusual RTP results from thermally activated excitonic coupling between different conformations of the compounds. Aggregation‐regulated excitonic coupling is observed when increasing the doping concentration of the emitters in poly(methylmethacrylate) (PMMA). Further, the RTP quantum efficiency improves more than 80‐fold in 1,3‐bis(N‐carbazolyl)benzene (mCP) compared to that in PMMA. This design principle offers important insight into triplet excited state dynamics and has been exploited in afterglow‐indicating temperature sensing. [ABSTRACT FROM AUTHOR]

Pure organic room‐temperature phosphorescence (RTP) materials have been widely utilized in security signs, anti‐counterfeiting, data encrypting, and other fields, which have attracted great attention. In the past few years, smart materials with color‐tunable organic RTP materials are reported by many researchers, while the work focused on the color‐tunable polymeric RTP materials is still rare, especially for molecular weight‐dependent polymeric RTP systems. Here, we designed and prepared three molecular weight polymers P1, P2, and P3 by different polymerization reaction times, and found that the fluorescence emissions of these polymer powders are various. Unexpectedly, the molecular weight‐dependent polymeric RTP materials are achieved through doping these polymers into polyacrylonitrile (PAN) matrix, and the International de l'Eclairage was redshift from (0.205,0.257) to (0.503,0.435). This phenomenon is ascribed to the different aggregation states formed by assembly of different molecular weight polymeric chains. Meanwhile, the electrostatic interaction between phosphor and PAN is hardly affected by water. Therefore, advanced information encryption can be achieved by using these polymeric phosphors as anti‐counterfeiting ink. [ABSTRACT FROM AUTHOR]

This is the first report of full‐color afterglow composites composed of four multicolored (blue, green, orange, and red) carbon dots (CDs) in polyacrylamide (PAM) matrix. Thus, adjustable four‐color room‐temperature phosphorescence (RTP) CDs@PAM composites are prepared on a PAM platform. The abundant amide groups in PAM are connected to the functional groups in CDs by hydrogen bonds, which promote the intersystem crossover and inhibit the non‐radiative relaxation of triple states (T1) in CDs@PAM and effectively shield the quenching agents such as oxygen. Furthermore, the rigid hydrogen bond mesh structure is beneficial to the stability of T1 in CDs@PAM. In addition, the results of electron spin resonance reveal that the afterglow of CDs@PAM composites is not caused by oxygen defects and the increase of oxygen defects hinders the emission of phosphorescence. The CDs@PAM composites display not only multi‐color fluorescence from blue to red, but also display full‐color RTP emission from blue to red with average phosphorescence lifetime in the range of 637–478.97 ms. These composites, in addition to the full‐color RTP performance, are promising for multi‐color pattern anti‐counterfeiting and information encryption. [ABSTRACT FROM AUTHOR]

Room-temperature phosphorescence (RTP) with a dynamic feature endows organic luminescent materials with promising application in optoelectronic fields. However, it remains a formidable challenge to obtain dynamic RTP materials. Herein, we reported a strategy for dynamic RTP via reversible transformation of radicals under external stimuli. RTP gradually disappeared with continuous UV-light irradiation owing to the conversion of NDIA to NDIA·− in NDIA/PVA film, which can be recovered by oxidation with oxygen. Regarding the excellent reversibility and repeatability, the potential applications for round-the-clock anti-counterfeiting and tag were first demonstrated. This finding not only outlines a principle to synthesize new RTP materials with dynamic behavior, but also expands the scope of applications of dynamic RTP materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Organic room-temperature phosphorescence (RTP) materials have garnered extensive attention owing to their long-lived excited states, low cost, good processability, and promising applications in domains such as anti-counterfeiting and information encryption, afterglow displays, biological imaging, and sensing. However, most current organic RTP materials are derived from artificial phosphors and petroleum-based polymers, hindering their practical applications owing to issues such as complicated synthesis and purification procedures, poor colour tunability, and lack of renewability and sustainability. Fortunately, the conversion of natural polysaccharides to RTP materials can address the issues. In this review, we summarize the recent advancements in natural polysaccharide-based RTP materials, including their design principles, underlying mechanisms, advanced luminescence characteristics, and potential applications. Special emphasis is placed on representative natural polysaccharide-based RTP systems exhibiting remarkable properties rarely observed in artificial phosphors. The discussion also focuses on intrinsic structure–performance relationships and outlines key challenges and perspectives for future development in this intriguing field. Overall, this review aims to detail guidelines and provide inspiration for the development of eco-friendly polysaccharide-based RTP materials, shedding new light on the high-value utilization of natural polysaccharides. [ABSTRACT FROM AUTHOR]

[Display omitted] Gradually enhancing afterglow under ambient conditions is generated by embedding a typical class of organic luminogens with ingeniousness lying in their architectures into melamine-formaldehyde polymer. Due to effective intramolecular motion resistance, the resulting material exhibits one of the most excellent polymer-based organic afterglow with a phosphorescence quantum yield (Φphos.) up to 38.31% and a lifetime (τphos.) up to 2.73 s. • Gradually enhancing afterglow under ambient conditions is generated. • Effective intramolecular motion resistance is achieved by host–guest doping. • The material exhibits one of the most fabulous polymer-based organic afterglow. • Locking intramolecular conformation contributes to suppressing nonradiative decay. Tackling the challenge of developing ultralong organic phosphorescence (UOP) materials with a high phosphorescence quantum yield (Φ phos.) and an ultralong phosphorescence lifetime (τ phos.) under ambient conditions is urgently needed. Herein, typical organic luminogens with simple chemical structures, namely, triphenylamine (TPA), 9-phenylcarbazole (PCz), and indolo[3,2,1- jk ]carbazole (ICz), are doped into a melamine–formaldehyde (MF) polymer matrix with a compact three-dimensional covalent network to prepare UOP materials, respectively. Both experiments and theoretical calculations suggest that restricting intramolecular motions to suppress the nonradiative decay of triplet excitons plays a critical role in achieving ultralong room-temperature phosphorescence from organic molecules in polymer matrices. The luminophore ICz with a planar and rigid chemical structure, constructed by locking the molecular conformation of TPA via carbon–carbon single bonds, exhibits a bright organic afterglow with a Φ phos. up to 38.31 % and a τ phos. up to 2.73 s in the MF polymer under ambient conditions, representing one of the most excellent polymer-based organic afterglow materials in comprehensive UOP performance. The gradual enhancement in UOP of the resulting luminescent materials has led to their successful use in multi-level anti-counterfeiting. This work provides an effective strategy for developing organic afterglow materials with both high Φ phos. and τ phos. values. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three new carbazole isomers were designed and synthesized. • The isomers show high-contrast RTP and mechanochromism. • The isomers show time-dependent RTP by host–guest doping. • The isomers show unusual anti-Kasha behaviors. • Lo-CzAD and Lp-CzAD simultaneously show RTP and TADF emission in PPh 3 matrix. To explore the intrinsic mechanism of pure organic room temperature and clustering-induced phosphorescence and investigate mechanochromism and structural-function relationships, here, 4-(2-(9H-carbazol-9-yl)phenyl)-2-amino-6-methoxypyridine-3,5-dicarbonitrile (Lo-CzAD), 4-(3-(9H-carbazol-9-yl)phenyl)-2-amino-6-methoxypyridine-3,5-dicarbonitrile (Lm-CzAD), and 4-(4-(9H-carbazol-9-yl)phenyl)-2-amino-6-methoxypyridine-3,5-dicarbonitrile (Lp-CzAD) were designed and synthesized by choosing self-made carbazole and 3, 5-dicyanopyridine (DCP) unit as electron acceptor and electron donor in sequence. Compared with crystals Lm-CzAD and Lp-CzAD, crystal Lo-CzAD shows better room temperature phosphorescence (RTP) performance, with RTP lifetimes of 187.16 ms, as well as afterglows 1s, which are attributed to twisted carbazole unit and donor–acceptor (D-A) molecular conformation, big crystal density and spin orbit coupling constant ξ (S 1 → T 1 and S 1 → T 2), as well as intermolecular H type stacking and small ξ (S 0 → T 1). By choosing urea and PPh 3 as host materials and tuning doping ratio, four doping systems were successfully constructed, significantly improving RTP performance of Lo-CzAD and Lp-CzAD, as well as showing different fluorescence and RTP. The lifetimes and afterglows of pure organic Urea/Lo-CzAD and Urea/Lp-CzAD systems are up to 478.42 ms, 5 s, 261.66 ms and 4.5 s in turn. Moreover, Lo-CzAD and Lp-CzAD show time-dependent RTP in doping systems due to monomer and aggregate dispersion, as well as clustering-induced phosphorescence. Based on the different luminescent properties, multiple information encryptions were successfully constructed. [ABSTRACT FROM AUTHOR]

Room-temperature phosphorescent (RTP) materials have attracted more and more attention due to their long luminescence life and large Stokes displacement. Host-guest doping systems are highly regarded for their simplicity of preparation and the absence of complex synthesis processes. Strong RTP emission can be activated by the doping of a guest molecules, in particular by substituting the phenyl group in the host structure with a naphthalene group. In this study, derivatives of benzophenone were constructed as the host molecule, and used 2-Benzoylnaphthalene, a commercially available naphthyl-substituted analogue of benzophenone, as the guest molecule. The phosphorescent lifetime of the doped system can reach 335 ms and the phosphorescent quantum yield can reach 58 %, which is expected to be used in anti-counterfeiting encryption, biological imaging and other fields. This work provides a general and effective host-guest doping strategy for constructing various organic room temperature phosphorescent materials. [Display omitted] • Doping naphthyl substituted analogues into the host molecule. • Benzophenone and its derivatives as "triplet exciton pumps". • Low-cost, high quantum yield RTP material. [ABSTRACT FROM AUTHOR]

• Long-emission phosphorescence activated by ortho -carboxyl substitution strategy. • Exploration of the multi-color phosphorescent carbon dots. • Tunable LEDs produced by using these carbon dots. While room temperature phosphorescence (RTP) associated with carbon dots (CDs) has been widely achieved, obtaining long-wavelength emission RTP, especially while mitigating the quenching effect of water or dissolved oxygen, remains a challenging yet desirable goal. We synthesized three types of phosphorescent CDs with varying luminescent properties by using three precursors with carboxyls positioned differently. The formation process of these CDs resulted in a well-ordered and compact structure, effectively inhibiting molecular vibrations and reducing non-radiative transitions. Consequently, it successfully prevented the quenching effect of dissolved oxygen on the RTP of CDs in an aqueous environment. Significantly, PA-AIBN synthesized with phthalic acid, rather than iso -phthalic acid and terephthalic acid, exhibited long-wavelength emission RTP, with the phosphorescent emission center reaching as far as 640 nm. To be specific, the ortho -substituted carboxyls played a critical role in boosting the formation of intramolecular hydrogen bonds. Simultaneously, an increase in the doping levels of both nitrogen (N) and phosphorus (P) in PA-AIBN facilitated the long-wavelength emission RTP. The increased sp2 conjugated carbon core of PA-AIBN narrowed the optical band gap, contributing to the long-wavelength emission. Taken together, these factors cooperatively promoted the long-wavelength emission of RTP. Importantly, the PA-AIBN synthesized in this study exhibited a broad half-peak width and long-wavelength emission. It was successfully used in the preparation of white-light-emitting diodes without the need for commercial phosphor powder, demonstrating its enormous potential for practical lighting devices. [ABSTRACT FROM AUTHOR]

• A new type of phosphorescent material without metal or organic fluorophores. • Carbon-related defects leading the intersystem crossing-based phosphorescence. • The rigid silica network ensuring the longevity of the phosphorescent emission. • Time-gated afterglow imaging system eliminating the tissue-autofluorescence. • Clear visualization-based diagnosis of subcutaneous tumors by high-contrast imaging. Room-temperature phosphorescence (RTP) has tremendous potential in optics and photonics. Unlike fluorescence, RTP has substantial afterglow signals even after the excitation light is removed, which allows for extended acquisition times and higher signal-to-noise ratio under time-gated bioimaging. However, conventional RTP materials, both metal-containing and metal-free organic compounds, typically have limited photostability and inherent toxicity, making them unsuitable for long-term biological applications. Here, we report metal- and organic fluorophore-free silica nanoparticles (SNPs) that facilitate long-lived phosphorescence and exhibit RTP for high-contrast bioimaging. Polycondensation of silicon precursors and silyl biphenyls forms biphenyl-doped SNPs (bSNPs), and thermal decomposition of biphenyl moieties generates optically active defects in the biphenyl-bonded silicate network. The calcined bSNPs (C-bSNPs) have RTP-related biphenyl defects composed of carbon impurities, corresponding to spectroscopic measurements and ab initio calculations. Facile surface functionalization of defect-engineered C-bSNPs with tumor-targeting peptides while maintaining long-lived RTP allows for tissue autofluorescence-free in vivo bioimaging for cancer diagnosis, surpassing the limitations of continuous-wave imaging. [ABSTRACT FROM AUTHOR]

Novel accessible scaffold featuring circularly‐polarized room‐temperature phosphorescence (RTP) is attractive but challenging. Herein, we report a new feasibly separable bidibenzo[b,d]furan compound with strong circularly‐polarized RTP when doping into the rigid polymer matrix. The simple silica‐gel column can separate the absolute chiral R‐isomer with excellent chiroptical properties. The experimental data reveal that the treated films exhibit an RTP efficiency of 14.8 %, a largest dissymmetric factor of 0.12, and a longest lifetime of 0.56 s under ambient conditions. It is found that reducing the nonradiative decays boosts the intrinsic circularly‐polarized RTP emission. The impressive results indicate that the locked axial chirality skeleton endows the potential of achieving superior circularly‐polarized emission for the small organic optoelectronic molecules. [ABSTRACT FROM AUTHOR]

There are limited reports about the transformation of pure organic room‐temperature phosphorescence (RTP) materials with multilevel stimuli‐responsiveness at different RTP emission wavelengths under external stimuli. It is difficult to ensure efficient intersystem crossing (ISC) in different states of a single‐component system. This research reports the conversion of the organic single‐component small molecule 1,2‐bis(4‐alkoxyphenyl)ethane‐1,2‐dione (N‐BOX) with multilevel stimuli‐responsiveness between high‐efficiency blue and yellow RTP by grinding or thermal annealing N‐BOX crystals. The RTP emission of N‐BOX in the crystalline state was easy to adjust by external stimuli (grinding or thermal annealing) due to its non‐compact packing, which led to a phase transition and generated unique multilevel stimuli‐responsiveness. In particular, the RTP quantum yield of 7‐BOX with multilevel stimuli‐responsiveness reached 68.4 %, which provides an opportunity for regulation of smart optical materials based on pure organic RTP. [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]

Although bowl‐shaped N‐pyrrolic polycyclic aromatic hydrocarbons (PAHs) can achieve excellent electron‐donating ability, their application for optoelectronics is hampered by typically low photoluminescence quantum yields (PLQYs). To address this issue, we report the synthesis and characterization of a series of curved and fully conjugated nitrogen‐doped PAHs. Through structural modifications to the electron‐accepting moiety, we are able to switch the mechanism of luminescence between thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP), and to tune the overall PLQY in the range from 9 % to 86 %. As a proof of concept, we constructed solid‐state organic light‐emitting diode (OLED) devices, which has not been explored to date in the context of concave N‐doped systems being TADF/RTP emitters. The best‐performing dye, possessing a peripheral trifluoromethyl group adjacent to the phenazine acceptor, exhibits yellow to orange emission with a maximum external quantum efficiency (EQE) of 12 %, which is the highest EQE in a curved D‐A embedded N‐PAH to date. [ABSTRACT FROM AUTHOR]

Organic room‐temperature phosphorescent (RTP) materials are useful in optical imaging and sensing technologies. However, most organic phosphors, including red‐light emitting dyes, exhibit unusually large Stokes shifts, and require excitation with ultraviolet radiation, the high energy of which can induce substantial photo damage. Here a design concept of using dihydroxy‐functionalized naphthalenediimide (NDI, λabs < 400 nm) is demonstrated to initiate ring‐opening polymerizations of L‐lactide (PLA) and ε‐caprolactone (PCL), resulting in a linear polymer NDI‐PLA2/NDI‐PCL2. With the right combination of substituents, the design simultaneously realizes broadband visible light absorption (λabs = 450–650 nm) and near‐infrared RTP (λRTP = 700 nm) with millisecond‐long lifetimes. Polymer site isolations of the aggregation‐prone NDI phosphors may prevent aggregation‐caused quenching of RTP common in bulk, by forming various microscopic ground‐state aggregates, which exhibit triplet‐emitting states lower than that of the individual phosphor. The method can potentially be expanded onto other molecular RTP systems. [ABSTRACT FROM AUTHOR]

To improve room‐temperature phosphorescence (RTP) property, thianthrene (TA) is chemically modified into three intramolecular dimers (1TA1TA, 1TA2TA, and 2TA2TA) at different active sites. They all show dual‐emission of fluorescence and RTP after deoxygenation when they are dispersed in polymer matrix to form films. As for the RTP emission among their films, 2TA2TA shows the largest red shift peaking at 540 nm, the longest lifetime of 36.5 ms, and the highest RTP efficiency of 40.7%. These RTP characteristics enable 2TA2TA to act as a self‐referenced ratiometric and colorimetric probe for oxygen sensing and detection at low concentration. As a result, 2TA2TA exhibits the highest quenching efficiency of 98.4% and highest sensitivity (KSV = 13.32 KPa−1) for quantitative oxygen detection. Besides, these oxygen‐sensitive materials can also be used to study aerodynamics through a direct and visual observation of emission intensity/color distribution. Overall, the new‐generation optical probe will be developed in oxygen sensing and detection with high sensitivity, good reversibility, and reproducibility by using the pure organic materials with single‐molecule dual‐emission of fluorescence and RTP through the dispersion of the materials in polymeric host. [ABSTRACT FROM AUTHOR]

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 FROM AUTHOR]

Near‐infrared (NIR) luminescent materials have received considerable attention owing to their intriguing applications in fields such as high‐resolution biological imaging and information technology. In this context, room‐temperature phosphorescence (RTP) materials with emission bands in the NIR region are rare. Metal‐free arylselanyl‐BODIPY triplet photosensitizers were doped into a benzophenone (BP) matrix. When excited at 350 nm, RTP emission was observed in the NIR region with λem values of 750–816 nm, and the phosphorescence quantum yield was up to 0.48 %. The detection of an extremely large Stokes shift (≥400 nm) was responsible for the triplet‐triplet energy transfer from BP to the BODIPY guest. Furthermore, the RTP properties were tuned by derivatization of the selenium‐containing BODIPY guests. NIR‐RTP properties were also detected upon excitation at 470 nm with a persistent lifetime of up to 17.5 ms. Notably, in addition to NIR RTP emission, thermally activated delayed fluorescence was detected at 620 nm when 10 ms delayed spectra were measured for the MeOSeBOD‐doped system. Considering the synthetic versatility of the BODIPY chromophore, this work opens up a new strategy for developing small molecule‐based NIR RTP systems. [ABSTRACT FROM AUTHOR]

A bromophenylpyridine derivative (BH-PY) was designed and synthesized as the guest molecule included in the cavity of cucurbit[8]uril (CB[8]) to form a 2:1 host–guest complex, which displays good room-temperature phosphorescence (RTP) in aqueous solutions. The interaction and optical properties of CB[8] with a guest in aqueous solution were investigated using 1H NMR spectroscopy, UV–Vis absorbance spectra, fluorescence and phosphorescence spectra and X-ray diffraction analysis in detail. The result showed that the bromophenyl moieties of the two guest molecules are included in the cavity of the CB[8] in a 'head-to-tail' stacking way, whereas the other part of BH-PY remains outside the portal to form a 2:1 supramolecular structurce, and supramolecular assemblies were applied for targeted phosphorescent imaging of mitochondria. [ABSTRACT FROM AUTHOR]

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 FROM AUTHOR]

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 FROM AUTHOR]

Seeking pure organic functional luminescent materials that are processed from green, low-cost, and sustainable resources remains a challenging but beneficial task. As an abundant natural polymer composed of crosslinked phenol ether units, lignin is a potential source of organic luminescent material because of the presence of extensive aromatic fragments. In the present work, a remarkable afterglow involving room-temperature phosphorescence (RTP) was achieved via simply embedding alkalized lignin into polyvinyl alcohol (PVA) matrix, and an ultralong luminescence lifetime of more than 160 ms was observed. More importantly, our study revealed that small fragments of hydrolyzed lignin (named LA-H) bearing extensive phenolic oxygen anions were the effective luminescent species. When embedded into a PVA matrix, LA-H showed remarkably high luminescence quantum yield and long lifetime of RTP emission compared with those of unprocessed lignin. Additionally, the various phenol oxygen anion moieties endowed LA-H with an excitation-dependent characteristic: the color-tunable RTP could be simply tuned from a maximum emission wavelength of 434–532 nm via altering the excitation wavelength. Thus, the color-tunable afterglow of emissive LA-H could be facilely obtained with a yield up to 38.4% using simple acid hydrolysis of lignin without other complex synthesis procedures. This work opens new avenues in the large-scale preparation of low-cost and sustainable pure organic RTP materials. [ABSTRACT FROM AUTHOR]

Triplet–triplet annihilation (TTA) is a feasible approach for utilizing electrically generated triplet excitons in organic light‐emitting diodes. However, low TTA efficiency is often observed in solids. Owing to the optically inaccessible nature of triplets, the main loss routes of the TTA process remain unknown. In this work, three vibrational emission peaks of the first excited triplet state (T1) are identified in the sensitized room‐temperature phosphorescence of TTA molecules. These peaks provide strong evidence of the loss channels of TTA. It is found that the monomolecular recombination of T1 represents an energy‐loss channel that combines the transient photoluminescence of both upconversion fluorescence and phosphorescence. Moreover, the study demonstrates that low‐energy vibrational T1 acts as an energy‐loss channel with only slight contributions to TTA. This work presents constructive insights into the improvement of TTA efficiency in solid films. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Carbon nanodots (CNDs) exhibiting concentration dependent properties have been synthesized through a one-pot hydrothermal reaction process utilizing diethylenetriamine and l-aspartic acid. At solid-state or high concentrations, the CNDs display excitation-wavelength independent fluorescence (FL) emissions, while at low concentrations, they exhibit excitation-wavelength dependent FL emissions. Detailed characterization of the structure and optical properties reveals that the concentration dependent FL properties can be ascribed to the intrinsic-state luminescence of the CNDs at low concentrations and the assembled-state luminescence at solid-state/high concentrations. With the increase of concentration, the self-assembly behavior of CNDs may cause the transition from intrinsic-state dominant luminescence to assembled-state dominant luminescence, and finally lead to the red-shift of FL color. Furthermore, the CNDs@Urea composites possess adjustable room-temperature phosphorescence (RTP) from turquoise to yellow by controlling the CNDs doping concentration. CNDs with concentration dependent optical properties have shown certain potentials in the fields of cell imaging, fingerprint recognition and anti-counterfeiting applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

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.

Although doping can induce room‐temperature phosphorescence (RTP) in heavy‐atom free organic systems, it is often challenging to match the host and guest components to achieve efficient intersystem crossing for activating RTP. In this work, we developed a simple descriptor ΔE to predict host molecules for matching the guest RTP emitters, based on the intersystem crossing via higher excited states (ISCHES) mechanism. This descriptor successfully predicted five commercially available host components to pair with naphthalimide (NA) and naphtho[2,3‐c]furan‐1,3‐dione (2,3‐NA) emitters with a high accuracy of 83 %. The yielded pairs exhibited bright yellow and green RTP with the quantum efficiency up to 0.4 and lifetime up to 1.67 s, respectively. Using these RTP pairs, we successfully achieved multi‐layer message encryption. The ΔE descriptor could provide an efficient way for developing doping‐induced RTP materials. [ABSTRACT FROM AUTHOR]

Monotonous luminescence has always been a major factor limiting the application of organic room‐temperature phosphorescence (RTP) materials. Enhancing and regulating the intermolecular interactions between the host and guest is an effective strategy to achieve excellent phosphorescence performance. In this study, intermolecular halogen bonding (CN⋅⋅⋅Br) was introduced into the host–guest RTP system. The interaction promoted intersystem crossing and stabilized the triplet excitons, thus helping to achieve strong phosphorescence emission. In addition, the weak intermolecular interaction of halogen bonding is sensitive to external stimuli such as heat, mechanical force, and X‐rays. Therefore, the triplet excitons were easily quenched and colorimetric multi‐stimuli responsive behaviors were realized, which greatly enriched the luminescence functionality of the RTP materials. This method provides a new platform for the future design of responsive RTP materials based on weak intermolecular interactions between the host and guest molecules. [ABSTRACT FROM AUTHOR]

Herein, new types of zero‐dimensional (0D) perovskites (PA6InCl9 and PA4InCl7) with blue room‐temperature phosphorescence (RTP) were obtained from InCl3 and aniline hydrochloride. These are highly sensitive to external light and force stimuli. The RTP quantum yield of PA6InCl9 can be enhanced from 25.2 % to 42.8 % upon illumination. Under mechanical force, PA4InCl7 exhibits a phase transform to PA6InCl9, thus boosting ultralong RTP with a lifetime up to 1.2 s. Furthermore, white and orange pure RTP with a quantum yield close to 100 % can be realized when Sb3+ was introduced into PA6InCl9. The white pure phosphorescence with a color‐rendering index (CRI) close to 90 consists of blue RTP of PA6InCl9 and orange RTP of Sb3+. Thus, this work not only overcomes long‐standing problems of low quantum yield and short lifetime of blue RTP, but also obtains high‐efficiency white RTP. It provides a feasible method to realize near‐unity quantum efficiency and has great application potential in the fields of optical devices and smart materials. [ABSTRACT FROM AUTHOR]

The photoreversible switch persistent room‐temperature phosphorescent (p‐RTP) system is attractive but challenging in the field of smart luminescent materials. In particular, those p‐RTPs with the excitation‐wavelength‐responsive and time‐dependent multicolor emission are very important but underexplored. Herein an excitation‐wavelength‐responsive and time‐dependent multicolor p‐RTP emission pseudopolyrotaxanes supramolecular system based on host–guest interaction between α‐cyclodextrin (α‐CD) and two luminophores (benzene and naphthalene) modified polyethylene glycol (PEG) derivatives is reported. The excitation‐wavelength‐responsive and time‐dependent multicolor afterglows of the supramolecular system are derived from the diverse p‐RTP emission species with different lifetimes. More importantly, the p‐RTP can be reversibly adjusted by photoisomerization of diarylethylene (DAE), that is, it could be erased under ultraviolet light and recovered under visible‐light for several cycles. Taking advantage of the reversible photoencryption property, this intelligent luminescence supramolecular system has broad application prospects in information storage and treatment. [ABSTRACT FROM AUTHOR]

Room‐temperature phosphorescence (RTP) from polymer carbon dots (PCDs) has attracted great attention for its potential applications in manufacturing anticounterfeit objects and digital encryption. However, most RTP raw materials with good performance are generally toxic, corrosive, and polluting, which will cause safety hazards during use and subsequent processing. Herein, facile, environmental‐friendly polymer carbon dots are prepared by hydrothermal treatment of gelatin and carboxylate (C‐PCDs) for the first time. The RTP of C‐PCDs is yellow emission and the lifetime up to 422 ms, which is three times that of PCDs produced only by gelatin. Then according to transmission electron microscope, atomic force microscopy, Fourier transform infrared, X‐ray photoelectron spectroscopy, gel permeation chromatography characterizations, and comparison of optical properties, it is found that the newly CONH formed by introduced carboxylate and free amino produced in the hydrolysis has an inhibitory effect on the hydrolysis of amide bonds contained in gelatin and deamination to a certain extent, which will be thought about more n‐π* transition from CO enhancing the conversion for triplet excitons. Moreover, the C‐PCDs with properties of fluorescence and phosphorescence are confirmed in the potential application of double anticounterfeiting under the excitation of ultraviolet lamps. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The organic solid-state light-emitting materials have attracted more and more attention owing to their promising applications in displays, lasers and optical communications. In contrast to isolated molecule, there are various weak intermolecular interactions in organic solids that sometimes have a large impact on the excited-state properties and energy dissipation pathways, resulting in strong fluorescence/phosphorescence. It is increasingly necessary to reveal the luminescence mechanism of organic solids. Here, we briefly review how intermolecular interactions induce strong normal fluorescence, thermally activate delayed fluorescence and room-temperature phosphorescence in organic solids by examining changes in geometry, electronic structures, electron-vibration coupling and energy dissipation dynamics of the excited states from isolated to aggregated molecules. We hope that the review will contribute to an in-depth understanding of the excited state properties of organic solids and to the design of excellent solid-state light-emitting materials. [ABSTRACT FROM AUTHOR]

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.

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.