Maximum Emission Peak Research Articles

Red and Near Infrared Emissive Bis‐Tridentate Ir(III) Phosphors for Organic Light Emitting Diodes

AbstractEfficient saturated red and near‐infrared (NIR) emissive materials are needed in the development of organic light‐emitting diodes (OLEDs), with applications extending beyond flat panel displays and lighting luminaries. Toward this aim, a series of bis‐tridentate Ir(III) complexes (3a ‒ 3c and 4a ‒ 4c) are designed and synthesized, showing emission spanning the region of 601‒694 nm in degassed toluene. Their emission tuning is mainly achieved using monoanionic chromophoric chelates, L1H for red and L2H for deep‐red and NIR, where the extended π‐conjugation and electron deficient N atoms are introduced synergistically. Moreover, three ancillary chelates, X1H2, X2H2, and X3H2, delivered a secondary influence via varied donor strength to the central Ir(III) atom. The resulting red and deep‐red OLED devices exhibit maximum (max.) external quantum efficiencies (EQEs) of 21.4% and 18.1% with peak maximum at 620 and 666 nm, respectively. More impressively, the device based on 4b delivers a NIR emission peak maximum at 702 nm with a maximum EQE of 10.0%.

Luminescent behaviors of orange-emitting SmxGd1−XBO3 phosphors by solid-state synthesis

In this study, GdBO3 phosphors doped with varying concentrations of Sm3+ were synthesized using the solid-state reaction technique at a temperature of 900 °C for 18 h. The SmXGd1−XBO3 phosphors were investigated on different chemical compositions, ranging from x = 0.000–0.150. The crystal structure exhibited a hexagonal GdBO3 phase. Excitation by a 403 nm wavelength resulted in the observed maximum emission peak at 604 nm from all SmXGd1−XBO3 phosphors. The highest emission intensity was achieved at x = 0.075. The emitted light was determined to be orange based on the calculated stimulated CIE chromaticity coordinates, and the correlated color temperature (CCT) was found to be 1634 K. Furthermore, the radioluminescence performance of the phosphors was measured to be 14.3 % and 113.9 % compared to that of commercial BGO and red luminescence powder, respectively.

Three pseudo-dimeric lead halide complexes containing derivatives of 8-hydroxyquinoline, Cl2QPbX (X = Br, I), (Cl2Q)4Pb2:Synthesis, crystal structures, and fluorescence spectroscopic properties

Three new complexes, namely (5,7-Dichloro-8-hydroxyquinoline)PbX (X=Br, I) (1, 2) and Pb2(5,7-Dichloro-8-hydroxyquinoline)4 (3), were synthesized through solvent evaporation at ambient temperature. The crystal structures and fluorescence emission properties of these complexes were systematically investigated. An analysis using single crystal X-ray diffraction revealed that complexes 1-3 form pseudo-dimeric structures through the interaction between lead and neighboring oxygen via secondary contacts. A comparison between the structures of complex 2 and [Pb(μ-Q)I]2, a complex of PbI2 with 8-hydroxyquinoline, showed that the coordination polyhedron changed from a triangular pyramid to a distorted tetrahedron. This change may be attributed to the site resistance effect of the chlorine substituents coordinated to the quinoline ring. Complex 3 has a layered structure formed through secondary contacts and intramolecular hydrogen bonding C-H⋯O and C-H⋯Cl among the lamellar molecules. The maximum emission peak at 489 nm, 505 nm, and 543 nm for complex 1-3 can be assigned to the ligand-to-metal charge transfer (LMCT). The maximum emission peaks were red-shifted by 22 nm, 38 nm, and 75 nm, respectively, compared to the ligand. The number of ligands increases the conformational rigidity of the structure and the electron density on lead atoms causing the molecular structure to change, the energy alters, and the fluorescence peaks to move in the long-wave direction.

Regulating fluorescent properties and ESIPT behavior of novel flavone-based fluorophore by replacing oxygen atom in proton donor/acceptor with sulfur atom: A TD-DFT study

Recently, the fluorescent phenomena of a new excited state intramolecular proton transfer (ESIPT) based fluorophore 3-hydroxy-2-(naphthalen-2-yl)-4H-chromen-4-one (HFN) has been reported experimentally. However, the first-hand dynamic information of its ESIPT process is still lacking theoretically. Based on density functional theory (DFT) and time-dependent DFT (TD-DFT) methods, the luminescent features and ESIPT processes of HFN and its two derivatives were studied in detail. Two HFN derivatives, 3-mercapto-2-(naphthalen-2-yl)-4H-chromen-4-one (TFN1) and 3-hydroxy-2-(naphthalen-2-yl)-4H-chromene-4-thione (TFN2) were obtained by replacing the oxygen atom of proton donor and proton acceptor in HFN with sulfur atom, respectively. The changes and effects of fluorescent properties and ESIPT process generated by different proton donors and proton acceptors are demonstrated. The simulated maximum absorption and emission peaks of HFN are well consistent with the experimental data. After replacing the oxygen atoms in proton donor and proton acceptor with sulfur atoms, the absorption wavelength of HFN slightly blue-shifts and red-shifts, respectively. And the fluorescence wavelengths of HFN obviously red-shift. The S0→S1 transitions of HFN and TFN1 are dominated by ππ* charge transfer transition, whereas the S0→S1/S0→S2 transition of TFN2 is a mixed charge transfer transition of nπ* and ππ*. The substitution of oxygen atom by sulfur atom in the proton donor or proton acceptor of HFN obviously decreases or increases the ESIPT barrier, due to its stronger proton-donating ability of S–H group or weaker proton-accepting ability of sulfur atom, respectively.

Two unique M-MOFs (M:Zn, Mn) based on various metal-oxygen chains for good sensitivity sensing and magnetic properties

In this paper, two novel two-dimensional MOFs were synthesized by solvothermal reaction of 2,4-di(2′,5′-dicarboxylphenyl)benzoic acid ligand and Zn(Ⅱ) and Mn(Ⅱ) metal ions: {[Zn2(HL)(H2O)(DMF)2]·(H2O)·(DMF)}n (1), {[Mn2(HL)(H2O)(DMF)2]·(H2O)·(DMF)}n (2). Complexes 1 and 2 are unique two-dimensional skeletons with particular metal-oxygen chains in their structures. The solid-state luminescence spectrum of complex 1 shows that its maximum emission peak is 448 nm. Further fluorescence studies of complex 1 show that it can efficiently detect Fe3+ and Cr2O72− in aqueous solution with a detection limit of 4.1 × 10−4 M and 2.7 × 10−4 M respectively, and has good recycling performance, so it is a potential bifunctional fluorescent probe material. The mechanism of fluorescence sensing quenching was also investigated in detail. Furthermore, magnetic studies have shown that there is an antiferromagnetic interaction between Mn(II) ions of complex 2.

One-step synthesis of all-inorganic high-entropy dual-phase Cs‘B’Br3/Cs‘B’2Br5 perovskite nanocrystals by high-energy ball milling

All-inorganic lead halide perovskite nanocrystals (NCs) have attracted considerable attention in field of optoelectronics due to their excellent properties such as high PLQY, tunable emission spectra in visible light region, and narrow emission peaks. However, problems existing in the research of all-inorganic lead halide perovskite materials are high lead content, low stability, and complex synthesis processes. Those problems need to be solved urgently. Therefore, dual-phase Cs‘B’Br3/Cs‘B’2Br5 perovskite material (Cs(Pb1/5Mn1/5Ni1/5Zn1/5Cd1/5)Br3/Cs(Pb1/5Mn1/5Ni1/5Zn1/5Cd1/5)2Br5) was synthesized by doping the B-site of CsPbBr3 and CsPb2Br5 using high-energy ball milling in this thesis. This dual-phase perovskite material has maximum absorption edge of 540 nm, a band gap width of 2.22 eV, the maximum emission peak at 600 nm with FWHM of 72 nm, PLQY of 24.50%, and an average fluorescence lifetime of 227.87 μs. After 21 days at room temperature, luminescent intensity of NCs increased to 156%, and still retained 109% at 120 days. After treatment at 150 °C, luminescent intensity decreased to 47%. Results show that this high-entropy dual-phase perovskite has great stability in different temperature. This proves that synthesis of high-entropy dual-phase halide perovskite by high-energy ball milling is feasible, and has great significance in solving poor stability and high lead content of all-inorganic lead halide perovskite in the future.

Design, synthesis, and characterization of pH-responsive near infrared bithiophene Aza-BODIPY

Aza-boron-dipyrromethene (Aza-BODIPY) have been favored by researchers for their excellent performance in photothermal therapy, photodynamic therapy, and bioimaging. In the field of phototherapy, Aza-BODIPY have been pushed forward because of their extensive variety and structural flexibility. Here, two bithiophene Aza-boron-dipyrromethene (Aza-BODIPY) NIR photosensitizers have been successfully synthesized (B5 and B6). Both of the bithiophene Aza-BODIPY exhibit high molar extinction coefficients and are red-shifted in wavelength. The maximum characteristic absorption peak is at 880 nm, and the maximum emission peak is at 880 nm. Bithiophene Aza-boron-dipyrromethene could simultaneously generate heat and singlet oxygen (1O2) under the irradiation of a single laser (808 nm). B5 and B6 each had photothermal conversion efficiencies of 39.84% and 58.14%. At the same time, B5 and B6 have photoacoustic signal generation under laser in the range of 680–900 nm. In addition, the ability of both to produce 1O2 at pH = 5 was significantly enhanced compared to pH = 7. as well as excellent photoacoustic properties. Most significantly, phototoxicity experiments showed that bithiophene Aza-BODIPY (B5) achieved the effect of killing 4T1 tumor cells effect. Finally, to improve the application of Aza-BODIPY, Pluronic F127 was used in self-assembly with the bithiophene Aza-BODIPY.

Redox‐Modulated Circularly Polarized Luminescence in Chiral Photonic Films Derived from Cellulose Nanocrystals and Polyoxometalate

AbstractAchieving smart circularly polarized luminescence (CPL) materials with large luminescence dissymmetry factor (glum) is in high demand for potential technological applications in the chiroptical fields. Herein, a series of chiral photonic crystals (CPCs) derived from cellulose nanocrystals (CNCs) and photosensitive inorganic polyoxometalates (POMs) through an evaporation‐induced self‐assembly strategy are reported. The photonic bandgaps (PBGs) of CPC films are well regulated by controlling the amount of doped POMs, yielding the tunable right‐handed CPL emission with tailored glum. By locating the maximum emission peak of POMs at the center of the PBG of CPC films, the composite shows remarkable CPL performance with a |glum| value up to 0.53. Furthermore, the CPL can be reversibly switched on/off through a fluorescence resonance energy transfer (FRET) process controlled by alternate UV irradiation reduction and air oxidation. The CPC films hold the great promise as next‐generation chiroptical memory devices.

Optical and scintillation properties of Yb-doped La2Hf2O7 crystal grown by core heating method for fiber reading remote-dosimetry system

(La0.99Yb0.01)2Hf2O7 (Yb:LaHO) crystal has been developed by the core heating method as a near-infrared-emitting oxide scintillator for a fiber reading remote-dosimetry system under the high-dose-rate region. This system consists of a scintillator, a long silica optical fiber and a detector unit. Near-infrared-emitting photons can be separated from significant fiber-derived noise mainly observed in the UV–blue range. The noise is generated in the optical fiber itself by gamma-rays and charged particles. The Yb:LaHO crystal had a maximum emission peak at 975 nm when excited by X-rays and a transmittance of approximately 29% at 977 nm. The afterglow intensity of the Yb:LaHO crystal under X-rays was 11% that of Cr:α-Al2O3 (ruby) crystal. We demonstrated the applicability of the remote-dosimetry system with the Yb:LaHO crystal irradiated with gamma rays from a 60Co source with an activity of ∼77 TBq. The signal-to-noise ratio (SNR) of the Yb:LaHO crystal was 1.9 times higher than that of the ruby crystal at ∼ 1 kGy/h, and the lowest limit of the dynamic range was comparable between the Yb:LaHO and ruby crystals. The results of the SNR and afterglow intensity showed that the Yb:LaHO crystal is a more suitable scintillator than the ruby crystal for fiber reading remote-dosimetry systems.

Donor–Acceptor–Donor Near-Infrared-II Aggregation-Induced Emission Luminogens (AIEgens) Encapsulated within Nanometer-Sized Exosomes for Tumor Imaging

Developing organic aggregation-induced emission luminogens (AIEgens) with a donor–acceptor–donor (D–A–D) structure improves fluorescence imaging for biological applications due to their deep tissue penetration, high fluorescence quantum yield, and good biocompatibility. However, compared to the systematically well-explored near-infrared-I (NIR-I, 650–900 nm) AIEgens, the research on organic D–A–D-type near-infrared-II (NIR-II, 1000–1700 nm) AIEgens received a snub, by contrast, owing to their lack of diversity, low AIE character, and poor tumor accumulation, which has become a bottleneck in the bioimaging field. Herein, we report a D–A–D-type organic NIR-II fluorophore with typical AIE character (αAIE > 4) through careful manipulation of the electron donor and acceptor. The tumor-associated macrophage (TAM)-derived exosomes with nanometer size were used as templates to encapsulate the NIR-II AIEgens (oBBT-DPNA) in a well-defined structure (named as AIE@Exo). The AIE@Exo displayed a superb aggregation-intensified NIR-II fluorescence with a maximum emission peak at 1052 nm as well as a calculated fluorescence quantum yield (QY) of 3.1%. Moreover, the in vivo application of AIE@Exo in efficient NIR-II fluorescence imaging of whole-body vessels and tumor was successfully demonstrated in living mice. Overall, the nanometer-sized biomimetic nanoparticles represent successful NIR-II AIE nanoparticles for biomedical imaging.

A viscosity-sensitive and mitochondria-targeted AIEgen effectuated fatty liver imaging and cancer photodynamic therapy

The mitochondrial targeting and viscosity-sensitive near-infrared fluorescence probe TQS-OH was an aggregation induced emission luminogen constructed by regulating the receptor structure and hydroxylating its terminal. TQS-OH presented more than 27.35-fold fluorescence enhancement at the maximum emission peak when the viscosity level increased from 0.49 to 1048 cP. It also appeared excellent reactive oxygen species production ability under white light irradiation and appeared strong photodynamic therapied effect on HepG2 cells. In addition, cellular co-location analysis implied that TQS-OH had accurate mitochondrial targeting ability, with co-location coefficient up to 0.95 in human hepatocellular carcinoma HepG2 cells and it also successfully achieved fatty liver imaging. Meanwhile, we found that TQS-OH induced cancer cell apoptosis by activating mitochondrial apoptosis pathway. Furthermore, TQS-OH ultimately has implemented the tumor photodynamic therapy with high efficiency in vivo, with a tumor inhibition rate as high as 50.77%. The above results made it a promising aggregation induced emission material for the diagnosis of fatty liver and tumor phototherapy.

Two unique 2D metal-organic frameworks based on various metal-oxygen chains for high sensitivity sensing of Fe(III) and Cr(VI) in aqueous media

Two new 2D MOFs, namely, {[Cd2(HL)(H2O)(DMF)2]·(H2O)·(DMF)}n (1), {[Co2(HL)(H2O)(DMF)2]·(H2O)·(DMF)}n (2) were constructed under the solvothermal conditions by using 2,4-di(2′,5′-dicarboxylphenyl)benzoic acid and d10 metal ion Cd(Ⅱ) and Co(Ⅱ). Because the diversity of ligands leads to two different coordination patterns in complexes 1–2, resulting in 1 and 2 with multiple structures. Both 1 and 2 exhibit a 3D supramolecular framework, which based on different metal-oxygen chains. The chains form a 2D layered structure through the carboxyl oxygen atoms in the ligand. The solid-state luminescence spectra of 1 at room temperature showed that the maximum emission peak is 458 nm (λex = 346 nm). At the same time, 1 showed high fluorescence selectivity and low detection limit for Fe3+ cations, Cr2O72− and CrO42− anions in aqueous solution, and can be used as a potential multifunctional material for the detection of these substances. In addition, the fluorescence sensing properties and quenching mechanism of the above ions are discussed in detail.

A fluorescent nanoprobe based on N/S co-doped carbon dots coupled with molecularly imprinted polymers for the detection of curcumin

Curcumin can be used to treat cancer diseases, however the side effects of excessive use are serious, and the dosage of curcumin should be accurately controlled. In this study, a fluorescence nanosensor using carbon quantum dots (N,S-CQD) embedded multifunctional molecularly imprinted polymer (N,S-CQD@MIP) composite was developed as a probe for the detection of curcumin. The N,S-CQD@MIP was synthesized by sol-gel method and found a maximum emission peak at 430 nm. The curcumin can be binded selectively by the specific interaction between recognition sites and template molecules. The corresponding sensing mechanism of N,S-CQD@MIP for the detection of curcumin is the result of fluorescence inner filter effect and the static quenching effect. The fluorescence nanosensor using N,S-CQD@MIP for the curcumin detection has a good linear relationship in the range of 0.339–136.0 μM, and the corresponding detection limit is as low as 1.357 nM. This method has been applied to detect the curcumin in real samples with the recoveries of 97.6–103.7%. These results indicate that N,S-CQD@MIP are potential sensing materials for curcumin detection.

Self-assembly of porous cellulose fibers and the incorporation of graphene carbon quantum dots for stable luminescence

Porous fibers as excellent carriers can be used to prepare photoluminescence materials. Herein, cellulose nanocrystals (CNCs) were derived from microcrystalline cellulose (MCC) by sulfuric acid hydrolysis. After CNCs were squeezed into a coagulating bath containing silicon precursors obtained by the hydrolysis of tetraethyl orthosilicate, porous cellulose fibers were constructed through self-assembly and then incorporated with graphene carbon quantum dots (GQDs) to prepare porous photoluminescence cellulose fibers. The silicon precursor amount, self-assembly time, and corrosion time were optimized. In addition, the morphology, structure and optical properties of the products were investigated. These results showed that as-prepared porous cellulose fibers with mesopores presented loose and porous mesh. Interestingly, the porous photoluminescence cellulose fibers exhibited blue fluorescence, and the maximum emission peak appeared at 430 nm under the excitation wavelength of 350 nm. Furthermore, the relative fluorescence intensity of the porous photoluminescence cellulose fibers was significantly enhanced compared with nonporous photoluminescence cellulose fibers. This work provided a new method to prepare environmentally and stably photoluminescence fibers, which had potential applications in anti-counterfeit packaging and smart packaging.

Four new coordination polymers with 2D → 2D interpenetrating networks and fluorescence quenching response to nitrobenzene

With the growing interests in two-dimensional (2D) materials, the rational assembly of new 2D coordination frameworks with functional properties have attracted extensive attentions. Four new isomorphic compounds with 2D → 2D interpenetrating structures, [M(cppp)2]n [M = Co (1), Cu (2), Ni (3) and Zn (4); Hcppp = 1- (4-carboxylphenyl)-3-(pyrid-4-yl) pyrazole] were rationally assembled through the reactions between suitable organic ligand (Hcppp) and metal nitrates. Compounds 1–4 were completely characterized by adsorption and desorption isotherms, elemental analysis, infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, single crystal X-ray diffraction and thermo-gravimetric analysis. The solid state fluorescence spectrum of compound 4 indicates an attractive blue luminescence behavior with a maximum emission peak at 473 nm, and the corresponding solvent-emulsions show turn-off fluorescence behavior to nitrobenzene (NB) in pure water environment. The quenching constant (KSV) and detection limit of compound 4 for electron-deficient NB reached 2.46×103 M−1 and 6.19×10–6 M, respectively. Notably, SEM and N2 adsorption-desorption isotherm indicated the block crystals of compound 4 after ultra-sonication can been effectively stripped into 2D lamellar structure, which can effectively provide recognition sites of π•••π interactions for NB. According to the experimental and theoretical simulation results, fluorescence quenching behavior of compound 4 by NB should be attributed to synergistic effects of competitive absorption between compound 4 and NB, Förster resonance energy transfer and photo-induced electron transfer. The fluorescence lifetimes of compound 4 in water and NB water dispersion indicate fluorescence sensing process was static.

PH-Sensitive Fluorescence Emission of Boron/Nitrogen Co-Doped Carbon Quantum Dots

Carbon quantum dots (CQDs) with their strong photoluminescence (PL) activity, high biocompatibility, robust stability, low cytotoxicity, and flexible surface structures have been employed in many fields including chemical sensing, biosensing, photocatalyst, energy storage, and biomedical applications. Of note, CQDs present an intrinsic pH-sensitive PL nature indicating their intense potential for pH-mediated sensing and imaging. Despite the numerous studies performed in the last two decades, the pH-sensitive PL mechanism of CQDs is still under debate and must be clarified to overcome the limitations in practical applications. Therefore, in this report, we performed a systematical study to determine the pH-sensitive PL nature of boron/nitrogen co-doped CQDs (B/N CQDs). In the first part, B/N CQDs with a strong blue emission were fabricated via a hydrothermal synthesis procedure. B/N-CQDs showed a strong blue PL emission with high quantum yield and excitation-dependent nature. Under the low pH conditions (pH 3), B/N-CQDs exhibited a robust green fluorescence emission with a significant red-shift (48 nm) and the loss of the excitation-dependent nature. The change in PL nature originated from the protonation of surface groups, a decrease in negative surface charge (from −20.6 to −1.23 eV), and finally, aggregation of the nanostructure (the size of CQDs from 4.8 to 7.5 nm). However, in the case of alkaline conditions, the deprotonation surface groups significantly enhanced the surface charge and led to the emergence of a negative ‘protective shell’ with a zeta potential of −71.3 eV. In a high pH medium (pH 13), PL spectra showed the loss of excitation-dependent features and a red-shift (35 nm) in emission peak maxima with lower intensity. This report provides significant progress in the clarification of the pH-sensitive PL mechanism of CQDs. We envision that the proposed CQDs would provide unique opportunities in the fabrication of novel pH sensor systems and fluorescence imaging where a wide range of pH sensitivity is required.

Development and x-ray imaging performance of Tb-doped GdAlO3-αAl2O3 submicron-diameter phase-separated scintillator fibers

Scintillators are key components in high-energy x-ray detectors for x-ray computed tomography, which are applied in medical diagnosis, nondestructive testing, and security inspection. Scintillators in x-ray imaging are required to have both high spatial resolution and sensitivity; however, a trade-off between spatial resolution and sensitivity exists. To improve the sensitivity of a scintillator, its thickness must be increased; however, spatial resolution deteriorates with increasing thickness. Here, we developed a well-aligned Tb-doped GdAlO3-αAl2O3 phase-separated scintillator fiber (PSSF) with a diameter of 1.25-μm by a micro-pulling-down method. The luminescence, scintillation, and imaging performances of a grown PSSF sample were evaluated. X-ray-induced radioluminescence measurements of the sample showed Tb3+ 4f–4f emissions in the wavelength range of 470–700 nm, and the maximum emission peak was at 550 nm. The contrast transfer function at 10 lp/mm was 82% for both 270 and 500 μm-thick PSSF samples. We calculated the luminescence index, which is the product of the scintillator’s light yield and sensitivity, of the samples and compared their values with commercially available conventional CsI:Tl columnar scintillators. The Tb-doped GdAlO3-αAl2O3 PSSF exhibits higher contrast transfer function and luminescence index values at above 60 keV x-ray region compared with the tested conventional scintillators.

One-Pot Synthesis and Characterization of CuCrS2/ZnS Core/Shell Quantum Dots as New Blue-Emitting Sources.

In this paper, we introduce a new blue-emitting material, CuCrS2/ZnS QDs (CCS QDs). To obtain bright and stable photoluminescent probes, we prepared a core/shell structure; the synthesis was conducted in a one-pot system, using 1-dodecanethiol as a sulfur source and co-ligand. The CCS QDs exhibited a semi-spherical colloidal nanocrystalline shape with an average diameter of 9.0 nm and ZnS shell thickness of 1.6 nm. A maximum photoluminescence emission peak (PL max) was observed at 465 nm with an excitation wavelength of 400 nm and PLQY was 5% at an initial [Cr3+]/[Cu+] molar ratio of one in the core synthesis. With an off-stoichiometric modification for band gap engineering, the CCS QDs exhibited slightly blue-shifted PL emission spectra and PLQY was 10% with an increase in initial molar ratio of 2.0 (462 nm PL max). However, when the initial molar ratio exceeded two, the CCS QDs exhibited a lower photoluminescence quantum yield of 4.5% with 461 nm of PL max at the initial molar ratio of four due to the formation of non-emissive Cr2S3 nanoflakes.

Synthesis, photoluminescence and electroluminescence properties of a new blue emitter with aggregation-induced emission and thermally activated delayed fluorescence characteristics

The emitters with aggregation-induced emission (AIE) and thermally activated delayed fluorescence (TADF) characteristics are in high demand in organic light-emitting diodes (OLEDs) owing to their strong fluorescence and high exciton utilization under electrical excitation. Herein, a blue emitter, 10-(3-((3,5-di(9H-carbazol-9-yl)phenyl)sulfonyl)phenyl)-9,9-dimethyl-9,10-dihydroacridine (m-CZ-DPS-DMAC), was synthesized by incorporating carbazole as skeleton, acridine as electron donor, and diphenyl sulfone as electron acceptor. m-CZ-DPS-DMAC emits weak fluorescence in good solvent, while it is obviously enhanced in the aggregate state, which is typical of AIE molecules. Meanwhile, the energy levels of the singlet and triplet states (ΔEST) of the molecule is relatively small, and it also exhibits obvious temperature dependence and oxygen sensitivity, which directly proves its TADF properties. In view of the above properties, a series of non-doped and doped OLEDs were prepared using m-CZ-DPS-DMAC as light-emitting layers. Among them, non-doped OLED (device A) displays blue emission (488 nm) with the turn-on voltage (Von), the maximum luminance (Lmax), the maximum current efficiency (CEmax), the maximum power efficiency (PEmax) and the maximum external quantum efficiency (EQEmax) of 2.6 V, 3460 cd m−2, 26.09 cd A–1, 29.26 lm W−1 and 10.05%, respectively. Doped OLED (device C) constructed based on m-CZ-DPS-DMAC doped 30% in DPEPO shows the satisfactory performance with the maximum emission peak of 486 nm, the Von of 2.8 V, the Lmax of 4571 cd m−2, the CEmax of 21.37 cd A–1, the PEmax of 22.37 lm W−1, and the EQEmax of 9.44%, respectively. The outstanding performance of m-CZ-DPS-DMAC proves that it is a potential material for designing blue OLEDs with AIE-TADF properties.

Linker engineering toward near-infrared-I emissive metal-organic frameworks for amine detection.

Herein, organic linker-based near-infrared-I (NIR-I) emissive metal-organic frameworks (MOFs), with a maximum emission peak at 741 nm, were synthesized via linker engineering. By integration of stronger acceptor and donor groups into one linker, a significant bathochromic-shift is realized. This MOF exhibits great selectivity and sensitivity for aniline and p-phenylenediamine detection. This finding provides new insights into the rational design of NIR-MOFs for sensing and related applications.