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Violet/deep-blue fluorescent organic light-emitting diode based on high-efficiency novel carbazole derivative with large torsion angle
摘要： A novel and highly efficient violet/deep-blue fluorescent carbazole and naphthalene-based compound (1) is designed and synthesized. The compound shows intensive violet/deep-blue fluorescence, high photoluminescence efficiency (0.72 in CH2Cl2, 0.65 in film) and narrow full width at half maximum (48 nm). The large torsion angles between carbazole and naphthalene guarantee the weak intermolecular interactions and suppress the π-π interactions in solid state, resulting in the highly efficient violet/deep-blue fluorescence. The maximum emission peak, luminance and external quantum efficiency for violet/deep-blue electroluminescence are 410 nm, 1326 cd/m2 and ～2%, respectively.
关键词： Carbazole,Naphthalene,Violet/deep-blue fluorescence,Organic light-emitting diodes
更新于2025-09-12 10:27:22
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Polarized Species in an Organic Semiconductor Laser
摘要： Meeting the challenge of direct electrically driven organic semiconductor lasers (OSLs), the design of OSL materials is under concern. Polarized species generally exist in conjugated organic materials and play an important role in the photophysics procedure; therefore, understanding these species is beneficial to designing novel OSL materials. Here, we use the amplified spontaneous emission effect as a medium to reveal a carbazole-benzothiadiazole-based polarized species that induced by charge transfer process. Spectroscopic analysis confirms that this polarized species that acted as a CT pair defect brings negative influence to both the ASE stability and solid state fluorescent quantum yield. It inspires us to be cautious for some specific molecular group combinations when designing OSL materials.
关键词： polaron,organic laser,carbazole,amplified spontaneous emission,charge transfer
更新于2025-09-12 10:27:22
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Solution-Processible Blue Fluorescent Dendrimers with Carbazole/Diphenylamine Hybrid Dendrons for Power-Efficient Organic Light-Emitting Diodes
摘要： Two blue ?uorescent dendrimers named PVAC2 and PVACA have been newly synthesized and investigated, where the carbazole/diphenylamine hybrid dendron is adopted instead of oligocarbazole. Compared with the reference dendrimer PVCt3, the emission maxima of PVAC2 and PVACA are found to be red-shifted accompanied by a slight reduction of the photoluminescence quantum yield in ?lms. Most importantly, the highest occupied molecular orbital level is elevated from ?5.35 eV of PVCt3 to ?5.20 eV of PVAC2 and ?4.95 eV of PVACA. Because of the favored hole injection, the turn-on voltage is accordingly decreased from 3.6 to 3.2 and 2.6 V. The value of PVACA is even lower than the theoretical limit of 2.78 V. In addition, PVAC2 exhibited the best nondoped device performance, showing a nearly doubled power e?ciency of 4.80 lm/W relative to PVCt3 (2.37 lm/W). The results clearly indicate that dendron engineering is also a promising strategy to develop solution-processible blue ?uorescent dendrimers capable of being used for power-e?cient organic light-emitting diodes.
关键词： solution-processible,blue fluorescent dendrimers,power-efficient organic light-emitting diodes,carbazole/diphenylamine hybrid dendron
更新于2025-09-12 10:27:22
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Universal host materials based on carbazole-formate derivatives for blue, green and red phosphorescent organic light-emitting diodes
摘要： The design of universal hosts suitable for different color dopants is still desired for efficient organic light-emitting diodes (OLEDs). In this work, two novel carbazole-formate based isomers (2CzMC and 4CzMC) with planar donor?π?acceptor (D?π?A) structures were designed and synthesized as the hosts for phosphorescent OLEDs (PhOLEDs). Due to the weak intramolecular charge transfer character and limited conjugation extensions, both 2CzMC and 4CzMC showed wide-bandgap emissions around 380 nm and high triplet energy levels (2.83 eV for 2CzMC, and 2.90 eV for 4CzMC). The photoluminescent spectra of 2CzMC and 4CzMC doped films with blue, green and red phosphors exhibited completely energy transfer from the hosts to the dopants. PhOLEDs devices with similar structures employing these doped film as emitter layers achieved excellent performance. Especially for 4CzMC-FIrpic based blue device, the external quantum efficiency (EQE) reached as high as 18.9%. This study showed a molecular design strategy to develop novel carbazole-based hosts for different color PhOLEDs.
关键词： Phosphorescent Organic Light-Emitting Diodes (PhOLEDs),Host,Carbazole,Wide-bandgap,Formate
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing RECENT TRENDS IN PURE AND APPLIED MATHEMATICS - Vellore, India (13–15 December 2018)] RECENT TRENDS IN PURE AND APPLIED MATHEMATICS - Non-linear optical properties of carbazole based dyes modified with diverse spacer units for dye-sensitized solar cells: A first principle study
摘要： Density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations were performed for evaluating the photophysical and photochemical properties of a sequence of carbazole based metal-free organic dyes modified using different π-conjugation spacer units, such as thiopine, pyrrole, furan, thiazole and isoxazole. Moreover, the modified dyes were subjected to investigation towards their non-linear optical (NLO) features. The results revealed that dipole moment (μ), static polarizability (α), anisotropic polarizability (?α) and hyperpolarizability (first order (β) and second order (γ)) of modified dyes are considerably enhanced as a consequence of changing the spacer unit. Likewise, light harvesting efficiency and oscillator strength of the modified dyes are enhanced upon wavelength of absorption is red-shifted by influence of spacer moieties. We believe that our calculations provide a more profound physical perception on structural property relationship for carbazole based dyes and give a hint to create potential sensitizers for opto-electronic and dye-sensitized solar cell applications.
关键词： dyes,DFT,carbazole,TDDFT,non-linear optical properties,dye-sensitized solar cells
更新于2025-09-12 10:27:22
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Nonacyclic carbazole-based non-fullerene acceptors enables over 12% efficiency with enhanced stability for organic solar cells
摘要： In this work, a nonacyclic carbazole-cored electron-rich central building block called CZTT and its derivated non-fullerene acceptors (CZTT-IC and CZTT-4F) are designed and synthesized. CZTT-4F with fluorination on the accepting end groups shows significantly down-shifted energy levels and a narrower bandgap as well as a smaller dipole moment under the ground state in comparison to the counterpart CZTT-IC. In the blend films, blends of both fluorinated donor and acceptor (PM6:CZTT-4F) reveal relatively decreased miscibility resulting in better donor/acceptor interpenetrating network with higher domain purity for efficient charge transport. Organic solar cells (OSCs) based on PM6:CZTT-4F blend exhibited a highest power conversion efficiency (PCE) of 12.07% with enhanced thermal and light soaking stability. To the best of our knowledge, this performance is among the highest for carbazole-based OSCs in the literature. The results reveal that the nonacyclic CZTT core is a promising building block for constructing efficient non-fullerene acceptors. More importantly, the relatively decreased miscibility within fluorinated CZTT-based blend film is demonstrated to greatly promote the stability of OSCs.
关键词： stability,nonacyclic carbazole,non-fullerene acceptors,organic solar cells,power conversion efficiency
更新于2025-09-11 14:15:04
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Facile-effective Hole Transporting Materials Based on Dibenzo[a,c]carbazole: The Key Role of Linkage Position to Photovoltaic Performance of Perovskite Solar Cells
摘要： Film morphology of hole-transporting layer is proved as the key element to charge transfer and interfacial property in perovskite solar cells. In this text, a new dibenzo[a,c]carbazole (DBC) core with multiple reaction sites has been formed with Y-shape, in which, the phenathrene group was integrated as a plane π structure into the common carbazole moiety. Accordingly, three DBC-based hole-transporting materials (HTMs) with varied molecular configurations were synthesized by the introduction of N-(4-methoxyphenyl)-9,9-dimethyl-9H-fluoren-2-amine (F(Me)NPh) as the periphery groups at different linkage positions. Once being applied to perovskite solar cells as HTMs, DBC-2 with the twisted and asymmetric structure achieved the highest conversion efficiency of 20.02%. Also, the corresponding dopant-free device exhibited the PCE of 16.43% and good device stability, under glovebox and ambient conditions.
关键词： hole-transporting materials,dibenzo[a,c]carbazole,perovskite solar cells,molecular configurations,photovoltaic performance
更新于2025-09-11 14:15:04
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Highly efficient TADF OLEDs with low efficiency roll-off based on novel acridine–carbazole hybrid donor-substituted pyrimidine derivatives
摘要： Dimethyl acridine (Ac) and carbazole (Cz) donors are fused to produce acridine–carbazole hybrid donors, 12AcCz (8,8-dimethyl-5-phenyl-8,13-dihydro-5H-indolo[2,3-c]acridine) and 23AcCz (13,13-dimethyl-7-phenyl-7,13-dihydro-5H-indolo[3,2-b]acridine). By combining TPPM (2,4,6-triphenylpyrimidine) acceptor with the Ac–Cz-fused donors of 12AcCz and 23AcCz, two emitters, 12AcCz-PM (13-(4-(2,6-diphenylpyrimidin-4-yl)phenyl)-8,8-dimethyl-5-phenyl-8,13-dihydro-5H-indolo[2,3-c]acridine) and 23AcCz-PM (5-(4-(2,6-diphenylpyrimidin-4-yl)phenyl)-13,13-dimethyl-7-phenyl-7,13-dihydro-5H-indolo[3,2-b]acridine), are designed and synthesized. The impact of the different fused topologies of the hybrid donors on molecular configuration, photophysical and optoelectrical characters are systematically investigated. For 12AcCz-PM, the large steric hindrance between donor and acceptor compels Ac of 12AcCz to be crooked, which endows it with the relatively planar quasi-axial conformation. No blatant TADF character is observed, but the 12AcCz-PM doped device still presents the ultradeep blue emission with CIEx, y of (0.15, 0.05) and maximum external quantum efficiency (EQEmax) of 6.4%. Whereas, 23AcCz-PM shows quasi-equatorial conformation and possesses notable TADF behavior. The 23AcCz-PM doped device reachs the EQEmax of 28.4% at low dopant concentration and 26.1% at high dopant concentration. Additionally, low efficiency roll-off (EQEs of 24.8% at 1000 cd m-2 and 20.7% at 5000 cd m-2) further confirms its superiorities as a TADF emitter.
关键词： novel acridine–carbazole hybrid donors,highly efficient TADF OLEDs,low efficiency roll-off,thermally activated delayed fluorescence
更新于2025-09-11 14:15:04
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Molecular Packing and Solid-state Fluorescence of Conjugated Compounds of Carbazole-acrylonitrile Derivatives
摘要： In this review paper, have been investigated three novel crystal structures of three molecules with carbazole substituents as the electron-donor group. These molecules, 2-(phenyl)-3-(N-ethyl-(3'-carbazolyl))acrylonitrile (I), 2-(3''-pyridyl)-3-(N-ethyl-(3'-carbazolyl))acrylonitrile (II), and 2-(4-pyridyl)-3-(N-ethyl-(3′-carbazolyl))acrylonitrile (III) in their structure, possess the electron-donor carbazole moiety, a -CN group attached to the double bond, and a phenyl or a pyridine function at the meta- or para-position. It was revealed with the help of single crystal diffraction X-ray analysis that there exists no difference in the crystal system, because all the compounds were crystallized in monoclinic system with space group P21/c. For determining the effect of the position of the nitrogen atom substitution on the crystal properties, has been analyzed and contrasted the molecular packing in a single crystal with that of other previously reported carbazole derivatives. The double bond bearing N-ethylcarbazole,–CN, phenyl or pyridine groups was observed to impart sufficient polarity in order to show slipped π-stacking aggregation in the solid state, affecting the compounds in the solid state and consequently affecting their fluorescence properties. The substitution at the para position was reported to exhibit more multiple C-H...π interactions as well as an interesting and unexpected short contact distance between adjacent N...N molecules those brought a conformational change resulting in an edge-to-face alignment in the molecules and affecting the best relative photoluminescence efficiency of the sample.
关键词： crystal structures,aggregation,cyano-substituted,Acrylonitrile derivatives,N-carbazole-acrylonitriles photophysical properties,TD-DFT calculations,pyridine derivatives
更新于2025-09-11 14:12:44
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Synthesis, photophysical, viscosity and DFT study of solid state fluorescent molecular rotors
摘要： Four novel Fluorescent Molecular Rotors (FMR) (1, 2, 3, 4) comprising carbazole, triphenylamine, phenothiazine, diethylaniline as donating groups and cyanoformyl vinylene as an accepting group are synthesized and characterized by NMR. They show emission in the solid state in the range of 581–651 nm. The viscosity sensitivity of emission was investigated 3.1–3.4 fold increase in emission intensity was observed in a mixture of polar protic ethanol and polyethyleneglycol 400 mixture. The experimental results are well in correlation with those of Density Functional Theory (DFT) computations. Compounds show higher values of dipole moment, linear polarizability values ranging from 49 to 59 × 10^?24 e.s.u., first order hyperpolarizability ranging from 77 to 250 × 10^-30 e.s.u. and second order hyperpolarizability ranging between 105–695 × 10^-30 e.s.u. suggest that the compounds show good Nonlinear Optical (NLO) property. The two photon absorption cross sections are found in the range 50–150 GM, which is further elucidated using Mulliken Hush analysis for analyzing effective charge transfer in the present compounds.
关键词： Photophysical study,Diethyl aniline,Triphenylamine,Carbazole,Viscosity sensitivity
更新于2025-09-10 09:29:36