Organic Thermoluminescence Driven by Electron Back Transfer: Microsecond Explosive Emission to Persistent Multi-Hour Afterglow.

Precise control over the release of light energy, distinct from conventional thermal energy management, poses significant challenges in luminescent technologies. This study pioneers organic above-room-temperature thermoluminescent materials using radical pairs as energy storage centers (ESCs), enabling controlled light energy release from multi-hour afterglows to microsecond-scale explosive bursts, accelerating the energy release rate by up to 1.8 × 10 times.

Recent advances of organic long persistent luminescence: Design strategy and internal mechanism.

Organic afterglow materials have drawn increasing attention for their great potential in practical applications. Until now, most of them just show the lifetimes in milliseconds or seconds, while the realization of long persistent luminescence (LPL) lasting for minutes or even hours is difficult. In 2017, Adachi and Kabe successfully realize the LPL with a duration longer than 1 hour in a purely organic system, which can be even comparable to some excellent inorganic materials.

New Molecular Photoswitch Based on the Conformational Transition of Phenothiazine Derivatives and Corresponding Triplet Emission Properties.

Molecular photoswitch research has drawn much attention in the last century owing to its great potential in the development of smart materials. However, photoswitches suitable for constructing light-responsive luminescent materials remain limited, especially those involving triplet-state phosphorescence. Herein, we designed a novel molecular photoswitch based on the conformation transition of phenothiazine derivatives, minimizing steric hindrance (-CH > -Cl > -F) to regulate the conformation transition process while introducing a cyanobenzene acceptor to promote phosphorescence emission potential.

HClO-Activated Near-Infrared Chemiluminescent Probes with a Malononitrile Group for In-Vivo Imaging.

Chemiluminescence (CL) imaging has emerged as a powerful approach to molecular imaging that allows exceptional sensitivity with virtually no background interference because of its unique capacity to emit photons without an external excitation source. Despite its high potential, the application of this nascent technique faces challenges because the current chemiluminescent agents have limited reactive sites, require complex synthesis, are insufficiently bright, and lack near-infrared emission. Herein, a series of HClO-activated chemiluminescent probes that exhibit robust near-infrared emission are studied.

Phenothiazine Derivatives as Small-Molecule Organic Cathodes with Adjustable Dropout Voltage and Cycle Performance.

Compared with conventional inorganic materials, organic electrodes are competitive candidates for secondary battery cathodes due to their resourcefulness, environmental friendliness, and cost-effectiveness. Much effort is devoted at the level of chemical structure, while ignoring the impact of molecular aggregation on battery behavior. Herein, this work designs a series of organic molecules with two electrochemically active phenothiazine groups linked by different lengths of alkyl chain to regulate molecular symmetry and crystallinity.

Ultralong Room-Temperature Phosphorescence with Second-level Lifetime in Water Based on Cyclodextrin Supramolecular Assembly.

Organic solid-state materials with long-lived room-temperature phosphorescence (RTP) emission have been widely developed and applied in many fields, while works in developing solution-phase phosphorescence materials were rarely reported owing to the ultrafast nonradiative relaxation and quenchers from the liquid medium. Herein, we report an ultralong RTP system in water through assembly based on a β-cyclodextrin host and -biphenylboronic acid guest with a lifetime of 1.03 s under ambient conditions.

Photo-Response with Radical Afterglow by Regulation of Spin Populations and Hole-Electron Distributions.

No matter photoinduced organic radicals have been reported frequently, they are usually non-luminescent at ambient conditions. The internal mechanism on stability and electronic transitions of photoinduced radicals, is thus crucial for the development of relevant materials. Herein, a series of photoinduced radical emission systems were developed conveniently through doping benzoic acids into the hydrogen donor polyvinyl alcohol (PVA) matrix.

The Effect of Molecular Conformations and Simulated "Self-Doping" in Phenothiazine Derivatives on Room-Temperature Phosphorescence.

The research of purely organic room-temperature phosphorescence (RTP) materials has drawn great attention for their wide potential applications. Besides single-component and host-guest doping systems, the self-doping with same molecule but different conformations in one state is also a possible way to construct RTP materials, regardless of its rare investigation. In this work, twenty-four phenothiazine derivatives with two distinct molecular conformations were designed and their RTP behaviors in different states were systematically studied, with the aim to deeply understand the self-doping effect on the corresponding RTP property.

Stimulus-responsive room temperature phosphorescence materials with full-color tunability from pure organic amorphous polymers.

Achieving stimulus-responsive ultralong room temperature phosphorescence (RTP) in organic materials especially with full-color tunable emissions is attractive and important but rarely reported. Here, a strategy was reported to realize stimulus-responsive RTP effect with color-tunable emissions by using water as solvent in the preparation process without any organic solvent through covalent linkage of arylboronic acids with different π conjugations and polymer matrix of polyvinyl alcohol. The yielded polymer films exhibit outstanding RTP performance (2.

Completely aqueous processable stimulus responsive organic room temperature phosphorescence materials with tunable afterglow color.

Many luminescent stimuli responsive materials are based on fluorescence emission, while stimuli-responsive room temperature phosphorescent materials are less explored. Here, we show a kind of stimulus-responsive room temperature phosphorescence materials by the covalent linkage of phosphorescent chromophore of arylboronic acid and polymer matrix of poly(vinylalcohol). Attributed to the rigid environment offered from hydrogen bond and B-O covalent bond between arylboronic acid and poly(vinylalcohol), the yielded polymer film exhibits ultralong room temperature phosphorescence with lifetime of 2.

Organic microporous crystals driven by pure C-H⋯π interactions with vapor-induced crystal-to-crystal transformations.

Organic porous crystals constructed by only a single kind of weak molecular interaction are invaluable to understanding the nature of the formation of organic porous materials and developing new types of porous materials. Here, we designed and synthesized two pure organic compounds of PBO and PBS through integrating planar dibenzothiophene/dibenzofuran and two phenothiazine groups together with twisted C-N bonds, which form organic microporous crystals with very good stability against strong acids and bases pure C-H⋯π interactions. Accordingly, the effective absorption of toluene has been successfully realized with an adsorbing capacity of 6.

Tunable Photoresponsive Behaviors Based on Triphenylamine Derivatives: The Pivotal Role of π-Conjugated Structure and Corresponding Application.

Photoresponsive materials have drawn much attention and are widely applied in daily life for their reversible changes in luminous color or appearance color under light irradiation. In this work, a new photoresponsive system based on triarylamine derivatives is developed. With the changed aryl substituents, adjustable photoresponsive properties, including photoactivated phosphorescence and photochromism after being dispersed into the poly(methyl methacrylate) (PMMA) matrix, are demonstrated.

Multistage Stimulus-Responsive Room Temperature Phosphorescence Based on Host-Guest Doping Systems.

Compared with inorganic long-lasting luminescent materials, organic room temperature phosphorescent (RTP) ones show several advantages, such as flexibility, transparency, solubility and color adjustability. However, organic RTP materials close to commercialization are still to be developed. In this work, we developed a new host-guest doping system with stimulus-responsive RTP characteristics, in which triphenylphosphine oxide (OPph ) acted host and benzo(dibenzo)phenothiazine dioxide derivatives as guests.

High Performance of Simple Organic Phosphorescence Host-Guest Materials and their Application in Time-Resolved Bioimaging.

The study of purely organic room-temperature phosphorescence (RTP) has drawn increasing attention because of its considerable theoretical research and practical application value. Currently, organic RTP materials with both high efficiency (Φ  > 20%) and a long lifetime (τ  > 10 s) in air are still scarce due to the lack of related design guidance. Here, a new strategy to increase the phosphorescence performance of organic materials by integrating the RTP host and RTP guest in one doping system to form a triplet exciplex, is reported.

Force-Induced Turn-On Persistent Room-Temperature Phosphorescence in Purely Organic Luminogen.

Research of purely organic room-temperature phosphorescence (RTP) materials has been a hot topic, especially for those with stimulus response character. Herein, an abnormal stimulus-responsive RTP effect is reported, in which, purely organic luminogen of Czs-ph-3F shows turn-on persistent phosphorescence under grinding. Careful analyses of experimental results, coupled with the theoretical calculations, show that the transition of molecular conformation from quasi-axial to quasi-equatorial of the phenothiazine group should be mainly responsible for this exciting result.

Persistent organic room temperature phosphorescence: what is the role of molecular dimers?

Molecular dimers have been frequently found to play an important role in room temperature phosphorescence (RTP), but its inherent working mechanism has remained unclear. Herein a series of unique characteristics, including singlet excimer emission and thermally activated delayed fluorescence, were successfully integrated into a new RTP luminogen of CS-2COOCH to clearly reveal the excited-state process of RTP and the special role of molecular dimers in persistent RTP emission.

Organic Dyes based on Tetraaryl-1,4-dihydropyrrolo-[3,2-b]pyrroles for Photovoltaic and Photocatalysis Applications with the Suppressed Electron Recombination.

A tetraaryl-1,4-dihydropyrrolo-[3,2-b]pyrroles (TAPP) moiety with the combination of two pyrrole rings and four phenyl moieties demonstrated strong electron-donating ability and nonplanar configuration simultaneously. Once incorporated into the organic dyes as a novel electron donor, it was beneficial for the enhancement of light-harvesting ability and suppression of electron recombination in the photovoltaic and photocatalysis systems. With the linkage of tunable conjugated bridges and electron acceptor, the corresponding organic dyes exhibited improved photovoltaic performance in dye-sensitized solar cells and facilitated photocatalytic hydrogen generation with a highest turnover number (TON) of 4337.

Molecular Conformation-Dependent Mechanoluminescence: Same Mechanical Stimulus but Different Emissive Color over Time.

A phenothiazine derivative of FCO-CzS with changeable mechanoluminescence is reported, which, upon continuous mechanical stimulus, shows mechanoluminescent emission from blue to white and yellow. Careful analysis of the experimental results, coupled with the well-understood photoluminescence theory, show that the molecular conformation transition of the phenothiazine group from quasi-axial to quasi-equatorial is responsible for this dynamic mechanoluminescence effect.

Elucidating the Excited State of Mechanoluminescence in Organic Luminogens with Room-Temperature Phosphorescence.

Two stable, purely organic luminogens exhibit both mechano- (ML) and photoluminescence (PL) with dual fluorescence-phosphorescence emissions at room temperature. Careful analysis of the crystal structures, coupled with theoretical calculations, demonstrate that room-temperature phosphorescence and ML properties are strongly related to molecular packing. In particular, the formation and fracture of molecular dimers with intermolecular charge-transfer properties has a significant effect on intersystem crossing, as well as excited triplet state emissions, in both PL and ML processes.

Conjugated or Broken: The Introduction of Isolation Spacer ahead of the Anchoring Moiety and the Improved Device Performance.

Acceptors in traditional dyes are generally designed closed to TiO substrate to form a strong electronic coupling with each other (e.g., cyanoacrylic acid) to enhance the electron injection for the high performance of the corresponding solar cells.

Different Effect of the Additional Electron-Withdrawing Cyano Group in Different Conjugation Bridge: The Adjusted Molecular Energy Levels and Largely Improved Photovoltaic Performance.

Four organic sensitizers (LI-68-LI-71) bearing various conjugated bridges were designed and synthesized, in which the only difference between LI-68 and LI-69 (or LI-70 and LI-71) was the absence/presence of the CN group as the auxiliary electron acceptor. Interestingly, compared to the reference dye of LI-68, LI-69 bearing the additional CN group exhibited the bad performance with the decreased Jsc and Voc values. However, once one thiophene moiety near the anchor group was replaced by pyrrole with the electron-rich property, the resultant LI-71 exhibited a photoelectric conversion efficiency increase by about 3 folds from 2.