10.1039/c6cc08501f
The research focuses on the development of structure-simplified, highly efficient deep blue organic light-emitting diodes (OLEDs) that exhibit reduced efficiency roll-off at extremely high luminance. The study involves the synthesis of new fluorescent emitters, NI-1-DPhTPA, NI-2-DPhTPA, BIDPhTPA, and PhIDPhTPA, based on a triphenylamine (TPA) core with electron-poor imidazole derivative groups. These emitters were characterized using 1H, 13C NMR spectrometry, mass spectrometry, and density functional theory (DFT) calculations to evaluate their molecular orbitals and energy band gaps. The thermal stability was assessed through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), while cyclic voltammograms (CV) were used to estimate HOMO levels. The photophysical properties, including absorption and photoluminescence (PL) spectra, were studied in various solvents to understand solvatochromic shifts and intramolecular charge transfer (ICT) characteristics. The electroluminescent properties of these materials were probed by fabricating non-doped multilayer OLEDs and simplified single-layer OLEDs, with the devices' performance evaluated through current density-voltage-luminance (J-V-L), external quantum efficiency (EQE), and power efficiency (PE) measurements. The research demonstrated record-breaking EQEs exceeding 5.10% at 10,000 cd m-2 for the multilayer devices and an unprecedented 4.22% EQE at 10,000 cd m-2 for the simplified single-layer devices, showcasing the potential for cost-effective, high-luminosity OLED applications.
10.1002/chem.201303522
The research focuses on the development of new aggregation-induced emission (AIE) active luminogens, specifically targeting the synthesis of efficient blue AIE emitters for undoped organic light-emitting diodes (OLEDs). The purpose of this study was to address the challenges associated with blue OLEDs, which often suffer from inferior performance due to the large band gap in blue luminogens. The researchers successfully synthesized two deep-blue fluorophores, TPE–pTPA and TPE–mTPA, along with six other compounds for comparison. These luminogens were designed to restrict the π-conjugation length, ensuring blue emission, by incorporating hole-dominated triphenylamine (TPA) and fluorene groups with high luminous efficiency, connected through unconjugated linkages. The study concluded that TPE–pTPA and TPE–mTPA exhibited the best electroluminescence performance with low turn-on voltages and high efficiencies, demonstrating that it is possible to enhance the OLED performance without sacrificing deep-blue emission through rational molecular design. Key chemicals used in the synthesis process included tetraphenylethene (TPE), triphenylamine (TPA), fluorene, and various other aromatic compounds. The researchers also utilized palladium-catalyzed Suzuki coupling reactions for the final product formation, with yields ranging from 60.4 to 85.9%. The compounds were purified and characterized using column chromatography and spectroscopic techniques.
10.1021/jo702002y
The study explores the development of highly fluorescent π-conjugated triphenylamines (TPAs) designed for large two-photon absorption (2PA) and biomolecule labeling. The researchers synthesized a set of TPA derivatives with functional linkers at various positions on one phenyl ring, allowing for the introduction of electron-withdrawing groups and chemical functions suitable for biomolecule conjugation. Key chemicals involved include trisformylated or trisiodinated intermediates, which enable the attachment of various electron-withdrawing groups and functional linkers. The monoderivatized three-branched compounds, particularly the benzothiazole (TP-3Bz) series, exhibit remarkable linear and nonlinear optical properties, such as high extinction coefficients, high quantum yields, and high 2-photon cross sections. The study also highlights that the presence of functional side chains does not disturb the two-photon absorption, and monoderivatized two-branched derivatives are also promising candidates for biomolecule labeling. The synthesized compounds' small size, good optical properties, and compatibility with bioconjugation protocols suggest they could be a new class of labels for tracking biomolecules using two-photon scanning microscopy.
10.1002/ejoc.201001165
The research focuses on the synthesis and characterization of highly soluble, multi-polar fluorene-based chromophores with multi-branched and dendritic architectures. These compounds were designed to exhibit strong two-photon absorption (2PA) properties, which were investigated in both femtosecond and nanosecond time domains. The study explores the relationship between the molecular structure, specifically the number of peripheral electron-donating groups and the size of the π-domain, with the two-photon activities of the model compounds. The experiments involved synthesizing four fluorene-based derivatives with systematic alterations in their molecular structure, which were then subjected to linear and nonlinear optical property measurements. These measurements included one-photon absorption (1PA) and fluorescence spectra, two-photon-excited fluorescence (2PEF) emission properties, and degenerate two-photon absorption spectra measurements. The reactants used in the synthesis included various fluorene and triphenylamine derivatives, along with catalysts and solvents. The analyses used techniques such as NMR, HRMS, and MALDI-TOF MS to characterize the synthesized compounds. The study demonstrated that the model compounds possess large nonlinear attenuation under nanosecond laser pulse irradiation, indicating potential applications as broadband and rapid-responsive optical limiters.
10.1080/15421401003608337
The study investigates the effects of intermolecular interactions on the characteristics of organic light emitting diodes (OLEDs) using four synthesized triphenylamine derivatives: 1,3,5-tris(4'-(100-phenyl-benzimidazol-200-yl)phenyl)amine (TPBB), MeO-TPBB, Br-TPBB, and Bu-TPBB. These derivatives were used as emitting layers in OLEDs with a multilayer structure [ITO=NPB (50 nm)=EML (30 nm)=TPBI (20 nm)=Alq3 (10 nm)=LiF (1 nm)=Al]. The research found that the substituents (methoxy, bromine, and n-butyl) significantly influenced the molecular mobility and intermolecular interactions of the TPBB derivatives, leading to different photoluminescence (PL) and electroluminescence (EL) characteristics. The unsubstituted TPBB showed better EL performance, while the substituted derivatives exhibited redshifted spectra and lower luminance and efficiency due to increased intermolecular interactions. The Br-TPBB derivative also experienced a significant decrease in performance due to the heavy atom effect of bromine.
10.1016/j.dyepig.2019.107689
This study investigates the design, synthesis, and properties of two torsional donor-acceptor cross-shaped luminophores, FB-CTPAEB and DFB-CTPAEB. These compounds exhibit unique intramolecular charge transfer (ICT) and solid-state fluorescence behaviors, and have high solid-state luminescence efficiencies (up to 0.693 and 0.442, respectively). 4,4''-Bis(trifluoromethyl)-[1,1':4',1''-terphenyl]-2',5'-dicarboxaldehyde (3a), prepared from 2,5-dibromoterephthalaldehyde and aromatic boronic acid 2a via Suzuki-Miyaura coupling reaction, is an intermediate for the synthesis of FB-CTPAEB. 3,3'',5,5''-Tetrakis(trifluoromethyl)-[1,1':4',1''-terphenyl]-2',5'-dicarboxaldehyde (3b), prepared from 2,5-dibromoterephthalaldehyde and aromatic boronic acid 2b via Suzuki-Miyaura coupling, is an intermediate compound used in the synthesis of DFB-CTPAEB. 2-(4-(Diphenylamino)phenyl)acetonitrile is used as the donor moiety in the Knoevenagel condensation reaction to form the final cruciform luminophore. 2,5-Dibromoterephthalaldehyde is the starting material for the synthesis of cruciform luminophores.
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