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A bipolar deep blue-emitting fluorescent material based on imidazole and triphenylamine for efficient non-doped OLEDs
摘要： A bipolar deep blue-emitting fluorescent material, 1-(4-tert-butyl phenyl)-2-[4-(N,N- diphenyl)phenyl]-4,5-diphenyl-1H-imidazole (TPA-PIM) has been designed and synthesized for efficient blue organic light-emitting diodes (OLEDs). The photophysical, thermal and electrochemical properties of TPA-PIM are investigated. TPA-PIM possesses high thermal stabilities with decomposition temperature of 396 °C and shows a strong deep-blue emission at 407 nm in N, N-dimethylformamide (DMF) solution. Single-carrier devices are fabricated to show that TPA-PIM has good bipolar characteristics. The non-doped fluorescent OLEDs using TPA-PIM as emitter exhibited stable and efficient deep-blue emissions with the CIE coordinates of (0.16, 0.09), the maximum luminance of 1392 cd m?2 and the maximum current efficiency of 2.60 cd A?1.
关键词： Triphenylamine,Blue light-emitting materials,Bipolar materials,Imidazole,Non-doped OLEDs
更新于2025-11-19 16:56:42
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Photophysical Properties of Phthalimide and Pyromellitic Diimide Tethered Imidazolium Nitrophenolate Salts
摘要： Structural aspects of the salt of 2-(3-(1H-imidazol-1-yl)propyl) isoindoline-1,3-dione (L1) with 2,4,6-trinitrophenol as well as the salts of N,N’-bis(3-imidazol-1-yl-propyl)-pyromelliticdiimide (L2) with 2,4-dinitrophenol (H24dnp) and 2,4,6-trinitrophenol (H246tnp) are reported along with the solid and solution studies on the photophysical properties of these salts. The fluorescence emission of the L1 and L2 are quenched by H24dnp and H246tnp both in solid and in solution. In solution the L1 has comparable binding constant with H24dnp and H246tnp but the relative ability to quench the fluorescence emission of L1 by H24dnp is less than the quenching abilities of the H246tnp. These two nitrophenols independently do not distinguish the L1 from L2 but the extent of quenching caused independently by the H24dnp or H246tnp on L1 or L2 make them easily distinguishable. Addition of water quenches the fluorescence emission of L1 and L2; but the addition of water to solution of the nitrophenolate salts result in the recovery of fluorescence emissions from the quenched states. The salts in solid state have short emission life-times. The PET effect prominently caused by mineral acids on L1 or L2 is not observed in the nitrophenolate salts. In solid state the O-π interactions contributed to stacking of the aromatic in the 2,4,6-trinitrophenolate salt of L2, hence it is non-fluorescent.
关键词： Binding of imidazole,Charge-assisted hydrogen bonds,Fluorescence,Cyclic imide,Nitrophenol derivatives
更新于2025-09-23 15:23:52
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Synthesis, photophysical properties and DFT studies of the pyridine-imidazole (PyIm) Cu(I) complexes: Impact of the pyridine ring functionalized by different substituents
摘要： A series of the pyridine-imidazole (PyIm) Cu(I) complexes with different substituents (bromide (P1), methyl (P2), and phenyl (P3)) attached on the pyridine ring are synthesized and characterized. All the complexes show the typical metal-to-ligand charge transfer (MLCT) absorption in the visible region. Complex P1 with an electron-withdrawing substituent on the pyridine ring, e.g., a bromine group, shows a red shift of the emission wavelength. Conversely, an electron-donating substituent on the pyridine ring in complex P2, e.g., a methyl group, shifts the emission to longer wavelength. Similarly, complex P3 containing the extended π-conjugation system of the ligand also exhibits a red shift of the emission wavelength. All of the complexes exhibit efficient green-yellow emission in PMMA films at room temperature with emission wavelength of 547–569 nm and quantum yields of 24.8–53.0%. Meanwhile, DFT and TDDFT methods were employed to explain the photophysical properties.
关键词： Pyridine-imidazole,Copper (I) complex,Metal-to-ligand charge transfer,Molar extinction coefficient,Density functional theory
更新于2025-09-23 15:22:29
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New cyclic and acyclic imidazole-based sensitizers for achieving highly efficient photoanodes for dye-sensitized solar cells by potential assisted method
摘要： A series of systematically tailored aryl acyclic (biphenyl, dye 1 and 2) and cyclic (phenanthrene, dye 3 and 4) and methyl-substituted (dye 5) imidazole derivatives were synthesized and characterized for dye-sensitized solar cells (DSSCs) application. Anisole ancillary donor was attached to -NH position in the imidazole center to obtain dye 2 and 4. Cyclic voltammetry and UV-visible studies of all the dyes indicate their suitability for DSSC application. Among the synthesized dyes, dye 4 having phenanthrene donor and anisole ancillary donor showed highest power conversion efficiency (PCE) of 7.16% (JSC = 13.07 mA/cm2, VOC = 0.831 V, FF = 0.659). Dye 2 displayed the highest electron lifetime in the conduction band of photoanode and hence the open circuit voltage of DSSC based on dye 2 was highest among the dyes studied (0.865 V). By using a novel potential assisted dye staining process, the dye loading on the photoanode is enhanced by 18% in 1h, which in turn enhanced the PCE to 8.10%.
关键词： DSSC,J-V characteristics,Imidazole,Phenanthrene,IPCE,Biphenyl
更新于2025-09-23 15:21:01
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Pyrene[4,5-d]imidazole-based Derivatives with Hybridized Local and Charge Transfer State for Highly Efficient Blue and White Organic Light-emitting Diodes with Low Efficiency Roll-off
摘要： A family of pyrene[4,5-d]imidazole derivatives, PyPA, PyPPA, PyPPAC and PyPAC, with different excited state are successfully developed. Among them, PyPPA and PyPPAC possess hybridized local and charge transfer (HLCT) state endowing them with pure blue fluorescence as well as high quantum yields. The nondoped organic light-emitting diode (OLED) based on PyPPA displays Commission Internationale de L’Eclairage coordinates of (0.14, 0.13) and achieves a maximum external quantum efficiency (EQE) of 8.47%, which are among the highest value reported to date for nondoped blue HLCT OLEDs. The nondoped OLED based on PyPPAC exhibits a maximum luminance of 50046 cd m-2 locating in blue region with CIE coordinates of (0.15, 0.21) and harvests the EQE of 6.74% even when the luminance reached over 10000 cd m?2. In addition, they both reveal ultimate exciton utilizing efficiencies of nearly 100%. The potential of blue emitter of PyPPA with HLCT character for application in white OLED (WOLED) is further tested. The efficient two-color hybrid warm WOLED is successfully achieved, which provides the total EQE, power efficiency and current efficiency of up to 21.19%, 61.46 lm W?1 and 62.13 cd A?1, respectively. The nondoped blue OLEDs and hybrid WOLEDs present good color stabilities with low efficiency roll-offs. Our results prove that taking advantage of the HLCT state, nondoped blue OLEDs as well as hybrid WOLEDs with high performance could be realized, which have a promising prospect for the displays and lightings in the future.
关键词： white OLED,blue luminophore,nondoped blue OLED,HLCT state,pyrene-imidazole
更新于2025-09-23 15:19:57
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Imidazole-containing cyanostilbene-based molecules with aggregation-induced emission characteristics: photophysical and electroluminescent properties
摘要： Organic luminogens with aggregation-induced emission (AIE) characteristics have recently attracted great research interest due to their excellent luminescence behavior in the aggregate state. Cyanostilbene is a well-known AIE-active moiety due to its unique luminescence mechanism and widespread use in the design of optical materials. In this work, we report two symmetrical imidazole-containing cyanostilbene derivatives with AIE activity, abbreviated as TPIA and PPIA, whose chemical structures only differ by a C–C bond. Both molecules are thermally stable and fabricated as electroluminescent (EL) devices. On one hand, the study of their photophysical properties confirms that the restricted intramolecular rotation (RIR) effect is still the dominant factor for the AIE effect in these two cyanostilbene-based molecules. On the other hand, the EL results reveal that a more conjugated molecular structure is beneficial for the EL properties. Moreover, the optimization of the device configuration with an electron-blocking layer significantly improves the EL performance. The orange-emissive PPIA-based device shows a high external quantum efficiency of 1.02% with a small efficiency roll-off.
关键词： Imidazole,Aggregation-induced emission,Cyanostilbene,OLEDs,Electroluminescence
更新于2025-09-19 17:15:36
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High-efficiency near-infrared fluorescent organic light-emitting diodes with small efficiency roll-off based on AIE-active phenanthro[9,10- <i>d</i> ]imidazole derivatives
摘要： The simultaneous realization of high-efficiency and low-cost in fluorescent organic light-emitting diodes (OLEDs) is still a formidable challenge in deep-red (DR)/near-infrared (NIR) region because of the intrinsic limitation of the energy-gap law and fluorescence quenching effect. Herein, three novel donor-acceptor-donor′ (D-A-D′) fluorophores, PIBz-10-PTZ, PIBz-10P-PTZ and PIBz-3-PTZ, by utilizing phenanthro[9,10-d]imidazole and phenothiazine as the donor, benzothiadiazole as the acceptor are synthesized. Owing to the unilateral steric hindrance between adjacent hydrogen atoms along the horizontal axis, PIBz-3-PTZ possesses a completely planar conformation and fully conjugated structure. PIBz-3-PTZ exhibits a strong DR emission and aggregation induced emission (AIE) property with a high photoluminescence quantum yield of 35% in neat thin film. The nondoped OLEDs achieved a maximum external quantum efficiency (EQE) of 2.02% with an emission peak at 672 nm and the brightness of up to 3403 cd m-2. In addition, the device was able to maintain an EQE of 1.69% at high luminance of 100 cd m-2, with a low efficiency roll-off of 16%, suggesting the nondoped device can keep the brightness.
关键词： Near-Infrared,High-Efficiency,AIE-active,Phenanthro[9,10-d]imidazole Derivatives,Organic Light-Emitting Diodes,Small Efficiency Roll-Off,Fluorescent
更新于2025-09-19 17:13:59
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Effect of imidazole based polymer blend electrolytes for dye-sensitized solar cells in energy harvesting window glass applications
摘要： The exploration of polymer electrolyte in the field of dye sensitized solar cell (DSSC) can contribute to increase the invention of renewable energy applications. In the present work, the influence of imidazole on the poly (vinylidene fluoride) (PVDF)- poly (methyl methacrylate) (PMMA)-Ethylene carbonate (EC)-KI-I2 polymer blend electrolytes have been prepared. The different weight percentage of imidazole added into polymer blend electrolytes has been prepared by solution casting. The prepared films were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermo gravimetric analysis (TGA), UV-visible spectra, photoluminescence spectra and impedance spectroscopy. The surface roughness texture of the film was analyzed by atomic force microscopy (AFM). The ionic conductivity of the optimized polymer blend electrolyte by impedance measurement, which is 1.95×10-3 S cm-1 at room temperature. The polymer electrolyte containing 40 wt% of imidazole content exhibits the highest photo-conversion efficiency of 3.04% under the illumination 100 mWcm-2. Moreover, a considerable enhancement in the stability of the DSSC device was demonstrated.
关键词： Polymer blend electrolyte,Imidazole,Dye-sensitized solar cell,Surface roughness,Ionic conductivity
更新于2025-09-12 10:27:22
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Nitrogen donor ligand for capping ZnS quantum dots: a quantum chemical and toxicological insight
摘要： Nanoparticles having strong optical and electronic properties are the most widely used materials in sensor development. Since the target analyte interacts directly with the surface of the material, the choice of ligand for functionalizing the surface of the material is the key for its further applications. The functionalized surface of the material makes it suitable for required applications as it controls the size of the particle during its growth from the solution phase. Biomolecule capped nanomaterials are favourable for various applications in bio-sensing. In the present work, an attempt has been made to explore the biologically active molecule imidazole as capping agent for ZnS semiconductor nanoparticles or quantum dots (QDs). This work explores the possibility of replacing conventional thiol-zinc bonding and hence paves new pathways for biomolecules having the possibility of being efficient capping agents. Computational chemistry has been used to study the mechanism of bonding between one of the nitrogen atoms of imidazole and the zinc ion of the ZnS QDs. The quantum chemical insight not only explores the most spontaneous interaction of zinc ion and imidazole molecule so as to act as an efficient capping agent but also explains the probable bonding site for nitrogen–zinc chemistry. The tailormade Mn doped ZnS QDs are one of the most promising materials for probe and sensor development. The ZnS core having non-toxicity and the emission in longer wavelength due to manganese makes this material highly useful biologically. The aqueous route of synthesis has been employed to obtain a highly homogeneous and pure material which was further characterized by UV (Ultra Violet spectroscopy), Spectrofluorometer, Transmission Electron Microscope and X-ray Diffraction. The toxicity at the cellular and genetic levels was also investigated to prove the potential of the imidazole capped Mn doped ZnS QD as a biocompatible material.
关键词： quantum chemical,Nitrogen donor ligand,biocompatibility,capping agent,toxicological insight,ZnS quantum dots,Mn doped ZnS QDs,aqueous synthesis,imidazole
更新于2025-09-11 14:15:04
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Synthesis and Properties of New Imidazole Derivatives Including Various Chromophore for OLEDs
摘要： Two new blue compounds were successfully synthesized by introducing phenanthroimidazole group as a side group into pyrene, a chromophore with good luminous efficiency: 1-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-2-(pyren-1-yl)-1H-phenanthro[9,10-d]imidazole (NA-PPI) and 1-(4’-(9H-carbazol-9-yl)-[1,1’-biphenyl]-4-yl)-2-(pyren-1-yl)-1H-phenanthro[9,10-d]imidazole (CP-PPI). The optical and electroluminescence properties of newly synthesized materials were measured. Both materials emit blue or sky-blue photoluminescence in the film state and have a high PLQY value of over 80% in solution state. The synthesized materials were applied as EML in non-doped devices, and high efficiency of 3.51 cd/A and EQE of 2.39% in CP-PPI device were achieved.
关键词： pyrene,blue emission,Organic light-emitting diode,imidazole,fluorescence
更新于2025-09-11 14:15:04