Organic Phosphorescence Research Articles

Hybrid Local and Charge-Transfer Material with Ultralong Room Temperature Phosphorescence for Efficient Organic Afterglow Light-Emitting Diodes.

Organic ultralong room temperature phosphorescence (OURTP) materials capable of combining various emission behaviors for diversified optoelectronic properties and applications have recently gained a vigorous development, but it remains a forbidden challenge in designing OURTP molecules with hybrid local and charge-transfer (HLCT) feature, possibly due to the elevated difficulties in simultaneously meeting the stringent requirements of both HLCT and OURTP emitters. Here, through introducing multiple heteroatoms into one-dimensional fused ring of coumarin with moderate charge transfer perturbation in donor-π-acceptor architecture, we demonstrate a HLCT-featured OURTP molecule showing both promoted fluorescence with a quantum yield of 77% in solution and long-lived OURTP with a lifetime of 251 ms in conventional host material used in electroluminescent device. Thus, efficient OURTP organic light-emitting diodes (OLEDs) were fabricated, exhibiting bright electroluminescence with an exciton utilization efficiency of 85% and yellow OURTP lasting over 2 s for afterglow. Impressively, the HLCT OURTP-OLEDs can be further optimized to reach an unprecedented total external quantum efficiency (EQE) of ~12% and OURTP EQE up to 3.11%, representing the highest performance among the reported OURTP-OLEDs. These impressive results highlight the significance to fuse HLCT and OURTP together in enriching OURTP materials and improving the afterglow OLED performances.

Resonance-Induced Dynamic Triplet Exciton Population for Photoactivated Organic Ultralong Room Temperature Phosphorescence.

Dynamically populating triplet excitons under external stimuli is desired to develop smart optoelectronic materials, but it remains a formidable challenge. Herein, we report a resonance-induced excited state regulation strategy to dynamically modulate the triplet exciton population by introducing a self-adaptive N-C═O structure to phosphors. The developed phosphors activated under high-power ultraviolet irradiation exhibited enhanced photoactivated organic ultralong room temperature phosphorescence (PA-OURTP) with lifetimes of up to ∼500 ms. The enhanced PA-OURTP was ascribed to activated N-C═O resonance variation-induced intersystem crossing to generate excess triplet excitons. The excellent PA-OURTP performance and ultralong deactivation time under ambient conditions of the developed materials could function as a reusable recorded medium for time-sensitive information encryption through optical printing. This study provides an effective approach to dynamically regulating triplet excitons and offers valuable guidance to develop high-performance PA-OURTP materials for security printing applications.

The Role of Locally Excited State and Charge Transfer State in Organic Room Temperature Phosphorescence and Corresponding Applications

AbstractDonor–acceptor (D–A) structure with charge transfer (CT) effect is widely utilized in the construction of organic luminescent materials. The adjustment of their CT effect and related luminescent property usually relies on the changes of molecular structure with different D or A moieties, which will lead to some uncertainties in structure‐property relationship. With the aim to explore the clear inherent luminescent mechanism for D–A molecule with CT effect, it is ideal that the regulation of intramolecular charge transfer in one same D–A molecule can be realized. Accordingly, three D–A type organic phosphorescence luminogens are designed and synthesized. Once being doped into different polymer matrixes, disparate charge transfer effects and related room temperature phosphorescence (RTP) properties can be achieved for a single molecule. Subsequent experiments confirm that different distributions of molecules with locally excited (LE) state and CT state are mainly responsible for their distinct RTP behaviors, exhibiting the well‐clarified structure‐property relationship of D–A type phosphorescence luminogens. Furthermore, the transition from CT to LE state can even be realized through chemical reaction, leading to the activated RTP effect for practical applications.

Versatile room temperature phosphorescence polymer with luminophore content as low as 0.05 wt%

To impart processability and practical serviceability to organic room temperature phosphorescence (RTP) molecules, and address phase separation and rigid confinement environment of conventional RTP polymers, a small amount of Schiff base bonds crosslinked tetraphenylene luminescence networks are pinned to the borate ester bonds crosslinked epoxy networks producing reversible interlocked polymer networks-based halogen-free RTP material. By taking advantage of the conjugation interaction of Schiff base linkages, and phase separation inhibition/molecular confinement effects of the interlocking networks, excellent fluorescence quantum yield (up to 78.9 %), RTP lifetime (660 ms) and quantum yield (16.7 %) are achieved with ultra-low concentration of luminophores (0.05 wt%). Moreover, the resultant acquires decent tensile strength (3.8 MPa) and a high elongation-at-break (365 %) owing to its unique molecular design. The phosphorescence lifetimes (457 ∼ 602 ms) are only slightly affected even after cyclic stretching (at 50 % strain for 100 cycles), or soaking in water (for 30 days), or heating (90 °C). The built-in reversible covalent bonds and the topological network reorganization further enable injection molding and self-healing of the material. Having been repeatedly crushed/hot-pressed, the recycled material still shows RTP lifetime and quantum yield of 398 ms and 14.6 %, respectively. The present work provides a feasible approach to fabricate multifunctional robust organic phosphorescent materials with application prospects.

Supramolecular assembly activated single-molecule phosphorescence resonance energy transfer for near-infrared targeted cell imaging

Pure organic phosphorescence resonance energy transfer is a research hotspot. Herein, a single-molecule phosphorescence resonance energy transfer system with a large Stokes shift of 367 nm and near-infrared emission is constructed by guest molecule alkyl-bridged methoxy-tetraphenylethylene-phenylpyridines derivative, cucurbit[n]uril (n = 7, 8) and β-cyclodextrin modified hyaluronic acid. The high binding affinity of cucurbituril to guest molecules in various stoichiometric ratios not only regulates the topological morphology of supramolecular assembly but also induces different phosphorescence emissions. Varying from the spherical nanoparticles and nanorods for binary assemblies, three-dimensional nanoplate is obtained by the ternary co-assembly of guest with cucurbit[7]uril/cucurbit[8]uril, accompanying enhanced phosphorescence at 540 nm. Uncommonly, the secondary assembly of β-cyclodextrin modified hyaluronic acid and ternary assembly activates a single intramolecular phosphorescence resonance energy transfer process derived from phenyl pyridines unit to methoxy-tetraphenylethylene function group, enabling a near-infrared delayed fluorescence at 700 nm, which ultimately applied to mitochondrial targeted imaging for cancer cells.

Urea-formaldehyde resin room temperature phosphorescent material with ultra-long afterglow and adjustable phosphorescence performance

Organic room-temperature phosphorescence materials have attracted extensive attention, but their development is limited by the stability and processibility. Herein, based on the on-line derivatization strategy, we report the urea-formaldehyde room-temperature phosphorescence materials which are constructed by polycondensation of aromatic diamines with urea and formaldehyde. Excitingly, urea-formaldehyde room-temperature phosphorescence materials achieve phosphor lifetime up to 3326 ms. There may be two ways to enhance phosphorescence performance, one is that the polycondensation of aromatic diamine with urea and formaldehyde promotes spin-orbit coupling, and another is that the imidazole derivatives derived from the condensation of aromatic o-diamine with formaldehyde maintains low levels of energy level difference and spin-orbit coupling, thus achieving ultra-long afterglow. Surprisingly, urea-formaldehyde room-temperature phosphorescence materials exhibit tunable phosphorescence emission in electrostatic field. Accordingly, 1,4-phenylenediamine, urea, and formaldehyde are copolymerized and self-assembled into phosphorescence microspheres with different electrostatic potential strengths. By mixing 1 wt% 1,4-phenylenediamine polycondensation microspheres with 1,4-phenylenediamine free microspheres, phosphor lifetime of the composite could be regulated from 27 ms to 123 ms. Moreover, vulcanization process enables precise shaping of urea-formaldehyde room-temperature phosphorescence materials. This work not only demonstrates that urea-formaldehyde room-temperature phosphorescence materials are promising candidates for organic phosphors, but also exhibits the phenomenon of electrostatically regulated phosphorescence.

Nylons with Highly-Bright and Ultralong Organic Room-Temperature Phosphorescence

Endowing the widely-used synthetic polymer nylon with high-performance organic room-temperature phosphorescence would produce advanced materials with a great potential for applications in daily life and industry. One key to achieving this goal is to find a suitable organic luminophore that can access the triplet excited state with the aid of the nylon matrix by controlling the matrix-luminophore interaction. Herein we report highly-efficient room-temperature phosphorescence nylons by doping cyano-substituted benzimidazole derivatives into the nylon 6 matrix. These homogeneously doped materials show ultralong phosphorescence lifetimes of up to 1.5 s and high phosphorescence quantum efficiency of up to 48.3% at the same time. The synergistic effect of the homogeneous dopant distribution via hydrogen bonding interaction, the rigid environment of the matrix polymer, and the potential energy transfer between doped luminophores and nylon is important for achieving the high-performance room-temperature phosphorescence, as supported by combined experimental and theoretical results with control compounds and various polymeric matrices. One-dimensional optical fibers are prepared from these doped room-temperature phosphorescence nylons that can transport both blue fluorescent and green afterglow photonic signals across the millimeter distance without significant optical attenuation. The potential applications of these phosphorescent materials in dual information encryption and rewritable recording are illustrated.

A cucurbit[8]uril-based supramolecular phosphorescent assembly: Cell imaging and sensing of amino acids in aqueous solution

In recent years, host-guest interactions of macrocycles have emerged as a promising approach to effectively enhance pure organic room-temperature phosphorescence by inhibiting the nonradiative relaxation while isolating the effects of oxygen and water molecules. In this work, a supramolecular assembly Q[8]-BCPI was constructed by 6-bromoisoquinoline derivative (BCPI) and cucurbit[8]uril (Q[8]). The assembly produced intense green room temperature phosphorescence (RTP) emission and enabled supramolecular recognition and detection of l-tryptophan (L-Trp) and l-tyrosine (L-Tyr). Moreover, the Q[8]-BCPI assembly showed good biocompatibility and low biotoxicity, and had a good staining effect on HeLa cells.

Photoactivated ultralong room‐temperature phosphorescence from epoxy polymer films doped with carbazole derivatives for erasable light printing

AbstractThe development of polymer‐based luminescent materials with efficient and switchable ultralong organic phosphorescence (UOP) under ambient conditions is of great importance but remains challenging. In this work, three new organic luminogens have been developed by attaching the ethyl benzoate to the nitrogen atoms of carbazole, 7H‐benzo[c]carbazole, and 7H‐dibenzo[c,g]carbazole via the Buchwald‐Hartwig coupling reaction, respectively. Subsequently, they are embedded into epoxy polymers through doping into the mixtures of bisphenol A diglycidyl ether and 1,3‐propylenediamine, followed by a thermal curing reaction. It is found that the resulting polymer films EB‐BCz@EP and EB‐2BCz@EP show unique photoactivated UOP properties. After UV light irradiation, their phosphorescence quantum yields are up to 7.6%, and the lifetimes reach 1.84 and 1.18 s, respectively. These observations suggest that it is possible to elevate the UOP lifetime without reducing the phosphorescence quantum yield by tuning the molecular structure of the guest luminogen. Upon thermal annealing, the photoactivated polymer films can recover to the pristine state, demonstrating switchable UOP characteristics of the polymer films in the air. Inspired by these exciting results, the EB‐2BCz@EP has been successfully explored as a transparent polymer film for erasable light printing.

Multimode Stimuli-Responsive Room-Temperature Phosphorescence Achieved by Doping Butterfly-like Fluorogens into Crystalline Small-Molecular Hosts.

Materials with stimuli-responsive purely organic room-temperature phosphorescence (RTP) exempt from exquisite molecular design and complex preparation are highly desirable but still relatively rare. Moreover, most of them work in a single switching mode. Herein, we employ a versatile host-guest-doped strategy to facilely construct efficient RTP systems with multimode stimuli-responsiveness without ingenious molecular design. By conveniently doping butterfly-like guests, namely, N,N'-diphenyl-dihydrodibenzo[a,c]phenazines (DPACs), featured with vibration-induced emission into the small-molecular hosts via various methods, RTP systems with finely tunable photophysical properties are readily obtained. Through systematic mechanistic studies and with the aid of a series of control experiments, we unveil the critical role of the host crystallinity in achieving efficient RTP. By virtue of the inherent environmental sensitivity of both RTP and fluorescence of the DPACs, our systems exhibit multiple-stimuli-responsiveness with the luminescence not only switching between the fluorescence and phosphorescence but also continuously changing in the fluorescence color. Advanced dynamic anticounterfeiting and multilevel information encryption is thereby realized.

Finely manipulating room temperature phosphorescence by dynamic lanthanide coordination toward multi-level information security

Room temperature phosphorescence materials have garnered significant attention due to their unique optical properties and promising applications. However, it remains a great challenge to finely manipulate phosphorescent properties to achieve desirable phosphorescent performance on demand. Here, we show a feasible strategy to finely manipulate organic phosphorescent performance by introducing dynamic lanthanide coordination. The organic phosphors of terpyridine phenylboronic acids possessing excellent coordination ability are covalently embedded into a polyvinyl alcohol matrix, leading to ultralong organic room temperature phosphorescence with a lifetime of up to 0.629 s. Notably, such phosphorescent performance, including intensity and lifetime, can be well controlled by varying the lanthanide dopant. Relying on the excellent modulable performance of these lanthanide-manipulated phosphorescence films, multi-level information encryption including attacker-misleading and spatial-time-resolved applications is successfully demonstrated with greatly improved security level. This work opens an avenue for finely manipulating phosphorescent properties to meet versatile uses in optical applications.

Highly stable ultralong organic phosphorescence from a 3D organic supramolecule constructed by halogen bonding and π–π interactions

Ultralong organic phosphorescence (UOP) materials have offered new exciting possibilities in the fields of photoelectric device, scintillators, anti-counterfeiting and bioprobe. However, pure organic phosphorescent materials inevitably suffer from rapid nonradiative transitions under oxygen, humidity, and high temperature, rending their phosphorescence is significantly quenched. Herein, a three-dimensional (3D) organic supramolecule (named SFIz) featuring UOP property was constructed successfully. Impressively, benefiting from the unique halogen bonding and π–π interactions, dual phosphorescent emission route of high energy state T1 (Br···O interaction predominates) and low energy state T1* (π–π interaction predominates) was simultaneously realized. Furthermore, owing to the robust supramolecular structural characteristic, SFIz shows highly stable UOP property with remarkably thermal, force stimulus and water-resistant stabilities that can be applied directly in extreme environments such as high temperatures 453 K (180 °C), high pressure and humidity. This work not only provides a much needed solution for achieving highly stable UOP materials and promoting their applications in extreme environments, but also gives in-depth understanding of both UOP and dual phosphorescent emission mechanisms in a non-metallic organic molecule.

Delayed room temperature phosphorescence enabled by phosphines

Organic ultralong room-temperature phosphorescence (RTP) usually emerges instantly and immediately decays after excitation removal. Here we report a new delayed RTP that is postponed by dozens of milliseconds after excitation removal and decays in two steps including an initial increase in intensity followed by subsequent decrease in intensity. The delayed RTP is achieved through introduction of phosphines into carbazole emitters. In contrast to the rapid energy transfer from single-molecular triplet states (T1) to stabilized triplet states (Tn*) of instant RTP systems, phosphine groups insert their intermediate states (TM) between carbazole-originated T1 and Tn* of carbazole-phosphine hybrids. In addition to markedly increasing emission lifetimes by ten folds, since TM → Tn* transition require >30 milliseconds, RTP is thereby postponed by dozens of milliseconds. The emission character of carbazole-phosphine hybrids can be used to reveal information through combining instant and delayed RTP, realizing multi-level time resolution for advanced information, biological and optoelectronic applications.

Altering central atoms and bromination sites of phosphorescence units to control ultralong organic room temperature phosphorescence

We report two strategies to expand the library of Phosphorescence Units, including altering the central atom and bromination. Directed by these two strategies, numerous new Phosphorescence Units can be designed. Due to the limitation of organic synthesis and commercial availability, eight organic units (BCz, NBF, BNT, BrBCz-1, BrBCz-2, BrBCz-3, BrBCz-4 and BrBNT) were obtained to verify our proposed methods and study the impact of central atoms and bromination sites on organic room temperature phosphorescence. Considering BCz, NBF and BNT (Group Ⅰ) together, when the central atom is N or S, the room temperature phosphorescence is on as BCz and BNT have higher ISC (Intersystem Crossing) efficiency than NBF; from N to S, phosphorescence wavelength red shifts because the T1 energy level is closely related to the central atom and the lifetime shortens due to different ISC efficiency. Considering BCz, BrBCz-1, BrBCz-2 and BrBCz-3 (Group Ⅱ), bromination and different bromination sites on the benzene ring matters much to ISC efficiency but little to the intrinsic T1 energy level, leading to dramatical increase of phosphorescence intensity, sharp drop of phosphorescence lifetime and subtle change of phosphorescence wavelength (color). Considering BrBCz-4 and BrBNT (Group Ⅲ), bromination on the naphthalene moiety greatly affects both ISC efficiency and the intrinsic T1 energy level, resulting in dramatical increase of phosphorescence intensity, sharp drop of phosphorescence lifetime and significant red shift of phosphorescence color. Therefore, BNT, BrBCz-1, BrBCz-2, BrBCz-3, BrBCz-4 and BrBNT can be regarded as new Phosphorescence Units while NBF cannot be. To our best knowledge, this work for the first time gives design suggestions of organic room temperature materials from the atomic level. This work may give a deep insight into organic phosphorescence from the perspective of Phosphorescence Units and lay foundation for their future applications.

Boosting organic phosphorescence in adaptive host-guest materials by hyperconjugation

Phosphorescence is ubiquitous in heavy atom-containing organic phosphors, which attracts considerable attention in optoelectronics and bioelectronics. However, heavy atom-free organic materials with efficient phosphorescence are rare under ambient conditions. Herein, we report a series of adaptive host-guest materials derived from dibenzo-heterocyclic analogues, showing host-dependent color-tunable phosphorescence with phosphorescence efficiency of up to 98.9%. The adaptive structural deformation of the guests arises from the hyperconjugation, namely the n→π* interaction, enabling them to inhabit the cavity of host crystals in synergy with steric effects. Consequently, a perfect conformation match between host and guest molecules facilitates the suppression of triplet exciton dissipation, thereby boosting the phosphorescence of these adaptive materials. Moreover, we extend this strategy to a ternary host-guest system, yielding both excitation- and time-dependent phosphorescence with a phosphorescence efficiency of 92.0%. This principle provides a concise way for obtaining efficient and color-tunable phosphorescence, making a major step toward potential applications in optoelectronics.

Elucidating the Crystallization‐Caused Phosphorescence Quenching Mechanism to Achieve Efficient Photoactivated Persistent Luminescence for High‐Quality Light Printing

AbstractThe development of polymer‐based luminescent materials with efficient photoactivated ultralong organic phosphorescence (UOP) is of great importance but very challenging. Herein, a new class of organic phosphorescent luminogens is constructed by attaching phenyl rings and/or ethyl benzoates to the nitrogen atoms of a planar aromatic heterocycle pyrrolodiindole (PDI). The compounds show a significant elevation in phosphorescence emission capability after incorporating the ester group(s). However, they cannot produce room‐temperature phosphorescence in the crystalline state. These observations are identified to be associated with the formation of dimers and excimers and the motions of substituents within the molecules. In this context, the PDI derivatives are doped into epoxy polymers with compact and permanent 3D covalent networks. The resulting polymer films show reversible photoactivated UOP under ambient conditions, with quantum yields and lifetimes of up to 24.4% and 2.03 s, respectively, thereby enabling high‐quality and erasable light printing and multi‐level anti‐counterfeiting applications. In addition, they also exhibit excellent water and chemical resistance. This work is conducive to understanding the generation and decay mechanisms of the triplet excitons of organic luminophores with planar aromatic heterocycles in the crystalline state and provides a direction for the development of high‐performance photoactivated UOP materials.

Responsive organic room-temperature phosphorescence materials for spatial-time-resolved anti-counterfeiting

Stimulus-responsive room-temperature phosphorescence (RTP) materials have gained significant attention for their important optoelectronic application prospects. However, the fabrication strategy and underlying mechanism of stimulus-responsive RTP materials remain less explored. Herein, we present a reliable strategy for achieving pH-responsive RTP materials by integrating poly(vinyl alcohol) (PVA) with carboxylic acid or amino group functionalized terpyridine (Tpy) derivatives. The resulting Tpy derivatives-based RTP materials displayed reversible changes in emission color, intensity, and lifetime of both prompt and delayed emission. Notably, the RTP emission undergoes a significant diminish upon exposure to acid due to the protonation of Tpy units. Taking advantage of the decent RTP emission and pH-responsiveness of these RTP films, a spatial-time-resolved anti-counterfeiting application is demonstrated as a proof-of-concept for largely enhancing the security level. This study not only provides new prospects for developing smart RTP materials but also promotes the advancement of optical anti-counterfeiting applications.

Ultralong MRTADF and Room‐Temperature Phosphorescence Enabled Color‐Tunable and High‐Temperature Dual‐Mode Organic Afterglow from Indolo[3,2‐b]carbazole

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

Manipulation of Photo‐Active Ultralong Organic Phosphorescence in Host‐Guest System

AbstractThe photo‐active ultralong organic phosphorescence (UOP) materials can only emit UOP gradually under consistent UV irradiation, which is primarily attributed to internal quenching of triplet oxygen, yet manipulating the rate of the photo‐activating process is seldom reported. In addition, amorphous small‐molecule doping UOP material is rarely reported either. In this study, a series of host and guest materials are synthesized and doped into amorphous UOP doping systems. These doping systems demonstrated a tunable photo‐activating rate (4–6 seconds to reach a saturated state), and the amorphous structure realized the sensitive detection of oxygen. The results affirm that triplet oxygen plays a pivotal role in determining whether UOP can be emitted, and importantly, it is established that a crystalline structure in small‐molecular doping systems is not a necessary condition. Furthermore, polymer‐based UOP materials, manufactured through co‐doping with both host and guest, exhibited tunable photo‐activating rates (4–16 s) and lifetimes (226.38–462.78 ms). To expand the application, the UV‐curing resin‐based UOP materials are prepared via 3D‐printing technology. This innovative work introduces a new approach for applying UOP materials in the field of amorphous doping system, providing a guiding strategy for widespread applications in oxygen detecting, time‐resolved information display and dynamic multi‐dimensional anti‐counterfeiting.

Crystalline nanoxylan from hot water extracted wood xylan at multi-length scale: Molecular assembly from nanocluster hydrocolloids to submicron spheroids

As a contribution to expand accessibility in the territory of bio-based nanomaterials, we demonstrate a novel material strategy to convert amorphous xylan preserved in wood biomass to hierarchical assemblies of crystalline nanoxylan on a multi-length scale. By reducing the end group in pressurized hot water extracted (PHWE) xylan to primary alcohol as a xylitol form with borohydride reduction, the endwise-peeling depolymerization is effectively impeded in the alkali-catalyzed hydrolytic cleavage of side substitutions in xylan. Nanoprecipitation by a gradual pH decrease resulted in a stable hydrocolloid dispersion in the form of worm-like nanoclusters assembled with primary crystallites, owing to the self-assembly of debranched xylan driven by strong intra- and inter-chain H-bonds. With evaporation-induced self-assembly, we can further construct the hydrocolloids as dry submicron spheroids of crystalline nanoxylan (CNX) with a high average elastic modulus of 47–83 GPa. Taking the advantage that the chain length and homogeneity of PHWE-xylan can be tailored, a structure-performance correlation was established between the structural order in CNX and the phosphorescent emission of this crystalline biopolymer. Rigid clusterization and high crystallinity that are constructed by strong intra- and inter-molecule interactions within the nanoxylan effectively restrict the molecular motion, thereby promoting the emission of ultralong organic phosphorescence.