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Isomeric emitters with the same donor and acceptor but different connection sites that have a non-negligible influence on molecular properties including radiative/non-radiative decays, reverse intersystem crossing, photophysical and electrical performances.

The citric acid-based diamines are a bio-based building block that combines adequate rigidity, good thermal stability, interesting optical activities, and good biodegradability for the construction of high-performance functional polyimides.

The Förster resonance energy transfer (FRET) process has been utilized to construct host–guest systems with stimuli-responsive room-temperature phosphorescence (RTP).

Developing highly efficient red/near-infrared thermally activated delayed fluorescence (TADF) materials is of great importance for organic light-emitting diodes (OLEDs). Here, we reported an asymmetric TADF emitter (TCPQ), which exhibits a high reverse intersystem crossing rate as well as a low non-radiative rate due to molecular symmetry breaking through multiple donor substitution. The coexistence of multiple donors endows TCPQ with not only near-infrared emission but also excellent device performances. As for the TCPQ-based OLEDs, the 10 and 20 wt % doped devices exhibit outstanding external quantum efficiencies (EQEs) of 21.9 and 19.2% with red emission peaks at 612 and 642 nm, respectively. Meanwhile, the non-doped device achieves an EQE of 5.4% with an emission peak at 718 nm, showing near-infrared emission. These device efficiencies are among the best performances of red/near-infrared TADF-OLEDs, demonstrating that the asymmetry design is a potential strategy for constructing long wavelength TADF materials with high efficiency.

Luminescent hydrogen-bonded organic frameworks (HOFs) have attracted increasing attention due to their corresponding luminescence that enables readily visualization of structural dynamics. HOFs wit...

Hybridized local and charge-transfer (HLCT) excited-state fluorophores, which enable full exciton utilization through a reverse intersystem crossing from high-lying triplet states to singlet state,...

AIE active photosensitizer of OMEPYH with benzophenone core and methylpyridinium group exhibited highly efficient generation of both type-I and type-II reactive oxygen species, which can be used for mitochondria-targeted photodynamic therapy (PDT).

Color-tunable dual-mode organic afterglow excited by ultraviolet (UV) and white light was achieved from classical aggregation-caused quenching compounds for the first time. Specifically, two luminescent systems, which could produce significant organic afterglow composed of persistent thermally activated delayed fluorescence and ultralong organic phosphorescence at ambient conditions, were constructed by doping fluorescein sodium and calcein sodium into aluminum sulfate. Their lifetimes surpassed 600 ms, and the dopant concentrations were as low as 5[[EQUATION]]10-6wt%. Moreover, the persistent luminescence colors of the materials could be tuned from blue to green and then to yellow by simply varying the concentrations of guest compounds or the temperature in the range of 260~340 K. Inspired by these exciting results, the afterglow materials were used for UV- and white-light-manipulated anti-counterfeiting and preparation of elastomers with different colors of persistent luminescence.

A pair of axially chiral organic enantiomers were facilely prepared through a one-pot sequential synthesis. They exhibit circularly polarized luminescence activities and have thermally activated delayed fluorescence (TADF) and aggregation-induced emission enhancement properties. Meanwhile, these two enantiomers present remarkable and reversible thermochromism in the crystalline state, enabling dual-colour TADF switching between orange and red. However, when they form cocrystals, the resulting racemate shows opposite thermochromic behaviors. These intriguing results probably emanate from their different optical activities, leading to distinct molecular packing modes and molecular conformation variations. Moreover, information encryption based on thermochromism of organic enantiomers and their racemate has been presented for the first time. This work may expand the application scope of chiral organic luminogens and pave a new way to construct intelligent luminescent systems., A pair of axially chiral organic enantiomers with circularly polarized thermally activated delayed fluorescence and aggregation-induced emission enhancement properties show opposite thermochromic behaviors to their racemate.

For achieving smart materials with color-tunable emissions, the development of single-component systems exhibiting high durability and stability is desired but remains challenging, in comparison to multicomponent systems. Here, a single-component luminescent molecule (3-SPhF) with colorful emissions is successfully reported through different expressions of triplet excitons in radiative transitions. The time-resolved spectra confirm the existence of delayed fluorescence (τ = 282.5 μs), monomeric phosphorescence (τ = 497.7 ms) and aggregated-state phosphorescence (τ = 230.0 ms) in the crystal powder of 3-SPhF, which affords time-dependent afterglow and excitation-dependent emissions in a steady state. Furthermore, the relationships between ultra-long luminescence and stacking of the dibenzofuran group in single crystals are explored, providing evidence for the regularity of multiple emission centers in single-component compounds with dibenzofuran substituents., Color tunable luminescent materials with multiple emission centers showing delayed fluorescence, single molecular phosphorescence and aggregated molecular phosphorescence are achieved, along with time-dependent and excitation-dependent properties.

Photoinduced organic radicals are important for chemical and physical processes of organic materials, which are extensively investigated and applied in organic synthesis, photoelectronic devices and biotechnology. However, there are rare reports of the luminescence for these photoinduced radicals, especially in the condensed state. Herein, an unexpected and interesting luminescent radical is described, which can be rapidly and reversibly generated from a simple organic crystal by gentle light irradiation in air. It was revealed that the twist and asymmetric conformation of isolated molecule in its crystal with only weak C-H⋅⋅⋅π intermolecular interactions, which led to the generation of such photoinduced luminescent radicals. In addition, dual-channel photosensitive device with rapid response and well repeatability can be obtained based on the thin film of this organic crystal, showing both photoswitching on luminescence and conducting.

Porous organic polymers (POP) are potential materials for fluorescent sensors because of their extended π-conjugated framework and porous structure. However, poor processability and photofunctionality are the major limitations for their practical applications. Here, a highly emissive photofunctional POP film (polyPhTPECz) was constructed using a simple in situ electropolymerization (EP) method. A novel high-luminescence aggregation-induced emission (AIE) molecule (PhTPECz), composed of multiple AIE groups as the central “core” and eight carbazole electroactive “arms,” was used as an electroactive precursor. Two possible twist conformations of polyPhTPECz were speculated and the corresponding pore diameters calculated to be ∼1.2 and 2.9 nm, respectively. These polyPhTPECz EP films were excellent multifunctional and reusable luminescent sensors for 2,4,6-trinitrophenol (TNP) and Fe3+ in an aqueous medium. The obtained limit of detection (LOD) was 3.8 and 10.0 nM for sensing TNP and Fe3+, respectively. These films also showed sensitive detection for TNP vapor. The fluorescence-quenching mechanism for TNP was a combination of electron transfer and resonance energy transfer. These excellent properties were mainly attributed to the high fluorescence property and cross-linked porous texture of these polyPhTPECz films.

It remains a challenge to detect n-alkanes, which contain only C–C and C–H groups. Herein pillararene sensors are developed toward n-alkane vapours. Fluorescence properties involving aggregation-induced emission have been innovatively demonstrated for pillar[5]arene compounds, including dimethoxypillar[5]arene (DMP[5]), difunctionalized (DBP[5] and DAP[5]) and perfunctionalized pillar[5]arene compounds (DEOP[5] and EOP[5]). The longer-wavelength emission at around 450 nm endows pillar[5]arene films with the ability to respond visually to various VOC (volatile organic compound) gases. DMP[5] and DEOP[5] films display fluorescent responses to nitrobenzene with high sensitivities (140 and 50 ppb). Notably, the luminescence of a transparent difunctionalized DBP[5] film displays both significant enhancements in fluorescence intensity and reduction in transparency toward n-alkane vapours (hexane, pentane and heptane) owing to host–guest interactions. The film sensors exhibit good recyclability in VOC sensing. The results highlight an innovative strategy to develop responsive sensors toward alkane vapours that are difficult to detect.

The precision regulation of the dielectric polarization and dielectric loss of polymer materials, developing intrinsic high-performance polymers with high dielectric constant, low dielectric loss and excellent temperature resistance is very challenging. In this work, a facile molecular design strategy was developed by directly introducing two ortho-position aromatic nitrile groups into the rigid polyimide backbone. Compared with similar polyimides without nitrile groups (0CN-PIs), the polarizability and dielectric constant of the designed polyimide (2CN-PIs) can be greatly increased. Meanwhile, the polarization motions of the nitrile groups can be limited at room temperature, which is beneficial to lowering the dielectric loss. Among the designed polyimides, 2CN-BTDA shows a high k value of 4.80, low dielectric loss of 1.57 × 10−3 at 1 kHz (25 °C), and breakdown strength of 219.4 kV mm−1 with high maximum discharge energy density of 1.023 J cm−3. Moreover, its Tg value is as high as 325 °C, much higher than that of most traditional dielectric polymers. The essence of designing high-k–low-loss intrinsic polymers was revealed by reconsidering the Clausius–Mossotti equation, where the total polarizability should be maximized while the chain stacking should be as tight as possible; that is, a rigid polymer backbone, small sized polar groups (like nitrile groups), and a spatial position in favor of orientation polarization are preferred. The results are helpful to promote the research progress of dielectric polarization and of great significance to the development of high-performance high-k–low-loss dielectric materials for potential applications in modern electronic information and microelectronic industry.

Pure organic emitters with full utilization of triplet excitons are in high demand for organic light-emitting diodes (OLEDs). Herein, through modulation of electron donors and introduction of phenyl rings as π spacers, we present three pure organic fluorophores (BCz, BTCz and BPTCz) with the hybridized local and charge-transfer (HLCT) excited state feature for OLED fabrication. Importantly, the introduction of π spacers in BPTCz not only enhances locally excited character with a fast radiative decay but also promotes intermolecular interactions to suppress non-radiative decays, contributing to a high solid-state fluorescence efficiency over 90%. Significantly, BPTCz not only endows its doped OLEDs with an external quantum efficiency (EQE) up to 19.5%, but also its non-doped OLED with a high EQE of 17.8%, and these outstanding efficiencies are the state-of-the-art performances of HLCT-based OLEDs., Three purely organic fluorophores with a hybridized local and charge-transfer excited state feature are presented and enabled organic light-emitting diodes with record high external quantum efficiencies close to 20%.

White-light emitting (WLE) polymers have attracted continuous attention for their promising applications in solid-state lighting, flexible display and related fields. However, achieving dual-emission and pure white-light emission in a single-component polymer is still challenging. In this study, a brominated single-component polymer BrOD-TFB was designed and synthesized, which shows dual-emission and white light emission properties in solution and room-temperature phosphorescence (RTP) in thin films. The dual-emission properties can be tuned by concentration, solvent polarity, and excitation energy. Spectral analyses and theoretical calculations reveal that the origin of the high-energy emission band (HEB) is intramolecular charge transfer (ICT) along the polymer chain, whilst the low-energy emission band (LEB) originates from the excited-state related to the intra-chain and inter-chain C-Br⋯π interactions as demonstrated by the single-crystal structure of the model compound. Appropriate control of the formation and the destruction of the halogen-assisted interactions can initiate white-light emission in the single-component polymer. More interestingly, by dispersing BrOD-TFB (0.1 wt%) in a non-emissive, colorless and transparent polymer, the characteristics of this white-light emission can be fully demonstrated while exhibiting unexpected RTP properties, with photoluminescence quantum efficiency (ΦPL) of up to 23% and CIE coordinates of (0.32, 0.32).

The traditional method to achieve ultralong organic phosphorescence (UOP) is to hybrid nπ* and ππ* configurations in appropriate proportion, which are contradictory to each other for improving efficiency and lifetime of phosphorescence. In this work, through replacing the electron-donating aromatic group with a methoxy group and combining intramolecular halogen bond to promote intersystem crossing and suppress non-radiative transition, an efficient UOP molecule (2Br-OSPh) has been synthesized with the longest lifetime and brightest UOP among its isomers. As compared to CzS2Br, which has a similar substituted position of bromine atom and a larger k

It remains a great challenge to develop polymer-based materials with efficient and color-tunable organic afterglow. Two indolocarbazole derivatives IaCzA and IbCzA have been synthesized and doped into poly(vinyl alcohol) (PVA) matrices. It is found that the resulting films can produce unique dual-mode afterglow, which is composed of persistent thermally activated delayed fluorescence and ultralong organic phosphorescence. Besides, the IbCzA-doped PVA film exhibits intense blue afterglow with Φ

Organic hole-transporting materials (HTMs) are an essential component in conventional perovskite solar cells (PSCs). In this work, two sulfonyldibenzene-based molecules, named CS-04 and CS-05, are synthesized and employed as HTMs in n-i-p PSCs. In comparison with CS-04, the carbazole-substituted methoxytriphenylamine (CzMOTPA) group in CS-05 exhibits an increased degree of molecular distortion, thus endowing CS-05 with excellent solvent solubility and film-formation ability. Moreover, CS-05 shows a high hole mobility, superior hole extraction and hole transporting properties. As a result, CS-05 yields impressive device performances with a high power conversion efficiency (PCE) of 20.15%, while that of CS-04 based device is 19.50%, which is comparable to that of the Spiro-OMeTAD based control device (19.59%). This finding illustrates the potential of sulfonyldibenzene-based molecules for the applications in PSCs, and also provides a novel avenue to improve the performances and stability of PSCs by tailoring the sulfonyldibenzene-based molecules.

Ultralong organic phosphorescence (UOP) has attracted increasing attention due to its potential applications in optoelectronics, bioelectronics, and security protection. However, achieving UOP with high quantum efficiency (QE) over 20 % is still full of challenges due to intersystem crossing (ISC) and fast non-radiative transitions in organic molecules. Here, we present a novel strategy to enhance the QE of UOP materials by modulating intramolecular halogen bonding via structural isomerism. The QE of CzS2Br reaches up to 52.10 %, which is the highest afterglow efficiency reported so far. The crucial reason for the extraordinary QE is intramolecular halogen bonding, which can not only effectively enhance ISC by promoting spin-orbit coupling, but also greatly confine motions of excited molecules to restrict non-radiative pathways. This work provides a reasonable strategy to develop highly efficient UOP materials for practical applications.

Organic thermally-activated delayed fluorescence (TADF) materials have been widely applied in organic optoelectronics, biological oxygen sensing, fluorescence probes, and imaging. Inspired by sulfo...

Luminophores usually suffer from luminescent quenching when introduced into a polymer backbone or side chain, which leads to the inefficient luminescence or even no luminescence of the polymer. In this work, alicyclic imide rings were found to be capable of balancing the donor-acceptor properties between the rigid spacer and the aggregation-induced emission-active fluorophore in light-emitting polymers. Along with the nonplanar and rigid emitter, the suppressed intramolecular charge-transfer effect and interchain disturbance can efficiently preserve the luminescence characteristics of the active center, resulting in high solid-state photoluminescence quantum yields of up to 89%. The amorphous polyimides exhibit excellent thermal properties, such as high glass transition temperature (Tg) values (398 °C) and high thermal decomposition temperature (Td) values (538 °C). As far as we know, these luminescent polymer materials are of excellent heat resistance with the highest luminescence efficiency reported. The results have significant impact for the precise prediction of the optical properties of light-emitting polymers by appropriate monomer design, providing controllable ways for synthesizing high thermal stability polymeric materials with efficient fluorescence properties.