Chromophores based on a donor−acceptor−donor structure possessing large two-photon absorption cross section and one or two mono-aza-15-crown-5 ether moieties, which can bind metal cations, have been synthesized. The influence of Mg2+ binding their one- spectroscopic properties has investigated. Upon binding, the action sections at 810 nm decrease by factor up to 50 high concentrations this results in contrast excited fluorescence signal between bound unbound forms, for excitation range 730...

Abstract A new approach to forming a gradient hole‐injection layer in polymer light‐emitting diodes (PLEDs) is demonstrated. Single spin‐coating of hole‐injecting conducting compositions with perfluorinated ionomer results work function through the formed by self‐organization, which leads remarkably efficient single‐layer PLEDs (ca. 21 cd –1 ). The device lifetime significantly improved 50 times) compared conventional layer, poly(3,4‐ethylenedioxythiophene)/poly(styrene sulfonate). These are...

Abstract Although significant progress has been made in the development of vacuum‐deposited small‐molecule organic light‐emitting diodes (OLEDs), one most desired research goals is still to produce flexible displays by low‐cost solution processing. The solution‐processed OLEDs based on small molecules could potentially be a good approach but no intensive studies this topic have conducted so far. To fabricate high‐performance devices molecules, underlying nature produced films and must...

Blue host materials for organic light-emitting diodes (OLEDs) based on silicon-cored (tetraphenylsilane) anthracene derivatives are synthesized. These compounds, with a non-coplanar molecular structure, have high glass-transition temperatures and good amorphous-film-forming capabilities. When doped blue-fluorescent dopant, blue emission color purity efficiency, up to 7.5 cd A(-1) 6.3%, is achieved.

The molecular parameters that govern charge transport in anthradithiophene (ADT) are studied by a joint experimental/theoretical approach involving high-resolution gas-phase photoelectron spectroscopy and quantum-mechanical methods. hole reorganization energy of ADT has been determined an analysis the vibrational structure lowest ionization band spectrum as well density-functional theory calculations. In addition, various dimers clusters molecules have considered order to understand effect...

The electron-donor abilities of ten aminophenyl systems and an additional aminothienyl system are compared using density functional theory calculations. studied here include those with amine nitrogen atoms bearing alkyl or aryl groups as part a heterocycle. Their to act donors in electron-transfer processes assessed from calculated vertical ionization potentials for the aminobenzenes, which good agreement available experimental data. intramolecular pi-electron conjugated inferred bond...

The living image: efficient two-photon probes AZn1 and AZn2 (see picture for rat brain tissue) show 24- to 52-fold excited fluorescence enhancement in response Zn2+. They can selectively detect intracellular free Zn2+ ions live cells tissues at a depth of 80–150 μm without interference from other metal the membrane-bound probes. Supporting information this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z800929_s.pdf or author. Please note: publisher not...

The degenerate and nondegenerate two-photon absorption (2PA) spectra for a symmetric an asymmetric fluorene derivative were experimentally measured in order to determine the effect of intermediate state resonance enhancement (ISRE) on 2PA cross section δ. ability tune individual photon energies (ND-2PA) process afforded quantitative study ISRE without modifying chemical structure investigated chromophores. Both molecules exhibited resonant nonlinearity with compound showing as much...

Move with the groove: Two-photon fluorescent pH probes and a two-photon lysotracker (AL1) can visualize acidic vesicles in live cells living tissue for long period of time without mistargeting photobleaching problems. Using AL1, be tracked real (see picture).

A new bipolar molecule containing hole-transporting and electron-transporting moieties has been synthesized characterized. The compound, 4,4′,4′′-tris(8-quinoline)-triphenylamine (TQTPA) exhibited good thermal stability luminescence properties. single-layer TQTPA light-emitting device shows sky blue emission with a low turn-on voltage of 2.8 V, maximum brightness greater than 7500 cd/m2 at 10 current efficiency 1.6 cd/A. Bipolar transport properties were investigated via the hole-only...

Abstract A theoretical study using density functional theory is undertaken to gain insight into how the structural, electronic, and electron‐transfer characteristics of three Fluoroarene‐oligothiophene semiconductors influence preferred transport electrons versus holes in field‐effect transistor applications. The intermolecular electronic coupling interactions are analyzed through both a simplified energy‐splitting dimer (ESID) model as function entire Hamiltonian order understand impact...

Reverse intersystem crossing (RISC) from triplet to singlet states has been recently introduced photophysics of organic chromophores. One type RISC occurs in donor (D)–acceptor (A) composites that form an exciplex manifold which the energy difference, Δ E ST between lowest (S 1 ) and (T levels is small (<100 meV) thus allowing at room temperature. This adds a delayed component photoluminescence emission widely known as thermally activated fluorescence. Here, it found electroluminescence...

Geometries and band gaps of polyaniline oligomers up to decamer have been systematically calculated analyzed using various computational techniques such as molecular mechanics, semiempirical, ab initio methods. On the basis fully optimized geometries neutral charged forms oligomers, excitation energies are at semiempirical ZINDO (INDO/S) level extrapolated gap value infinite chain. Band also approximated by extrapolating HOMO/LUMO difference density functional (B3LYP/6-31G*). The ZINDO//AM1...

Abstract The design of novel exciplex-forming co-host materials provides new opportunities to achieve high device performance organic light emitting diodes (OLEDs), including efficiency, low driving voltage and efficiency roll-off. Here, we report a comprehensive study system in OLEDs the change materials, mixing composition exciplex improve performance. We investigate various systems using 5-(3–4,6-diphenyl-1,3,5-triazin-2-yl)phenyl-3,9-diphenyl-9H-carbazole,...

Since the chemical and thermal stability of organic thin film layers in light-emitting diodes (OLEDs) highly influences operational device lifetime, a rational advanced design materials structures is quite necessary. Here, we report significant improvement lifetime blue-fluorescent OLEDs by adopting mixed electron transporting layer (mETL) 4,7-diphenyl-1,10-phenanthroline (BPhen) hydroxyquinolinolato-lithium (Liq). Compared to pristine BPhen film, Liq mixing improved morphological...

The hydrothermal reaction of elemental Ag, or water-soluble silver sources, with UO3 and I2O5 at 200 degrees C for 5 days yields Ag4(UO2)4(IO3)2(IO4)2O2 in the form orange fibrous needles. Single-crystal X-ray diffraction studies on this compound reveal a highly complex network structure consisting three interconnected low-dimensional substructures. first these substructures are ribbons UO8 hexagonal bipyramids that edge-share to one-dimensional chains. These units further pentagonal...

This letter introduces conducting polymer compositions which can be used for hole-injection layer in organic light-emitting diodes. The are composed of poly (3,4-ethylenedioxythiophene) (PEDOT), polystyrene sulfonic acid (PSS) and a perfluorinated ionomer. films based on these showed much higher workfunction (∼5.3–5.7eV) than conventional PEDOT/PSS (∼5.0–5.2eV). When we fabricated blue diodes by using as layer, the luminescent efficiency was improved device lifetime also enhanced relative to...

The nature of vibronic coupling in fused polycyclic benzene-thiophene structures has been studied using an approach that combines high-resolution gas-phase photoelectron spectroscopy measurements with first-principles quantum-mechanical calculations. results indicate general the electron-vibrational is stronger than hole-vibrational coupling. In acenedithiophenes, main contributions to arise from medium- and high-frequency vibrations. thienobisbenzothiophenes, however, interaction holes...

The syntheses of the bright deep blue emitting mixed ligand Ir(III) complexes comprising two cyclometalating, one phosphine and cyano, ligands are reported. In this study, a firm connection between nature excited states physicochemical behavior with different systems is elucidated by correlating observed crystal structures, spectroscopic properties, electrochemical properties theoretical results obtained density functional theory (DFT) methods. cyclometalating used here anions...

Strip-patternable organic semiconducting thin layers are successfully deposited by self-metered slot-die coating to achieve bright and efficient solution-processable OLEDs.

A new type of organic light‐emitting diode (OLED) has emerged that shows enhanced operational stability and large internal quantum efficiency approaching 100%, which is based on thermally activated delayed fluorescence (TADF) compounds doped with fluorescent emitters. Magneto‐electroluminescence (MEL) in such TADF‐based OLEDs magneto‐photoluminescence (MPL) thin films donor–acceptor (D–A) exciplexes emitters various concentrations are investigated. It been found both MEL MPL responses...

Low operational stability is the main limiting factor for commercialization of blue phosphorescent organic light emitting diodes (PhOLEDs). The high energy and long lifetime triplet excitons in PhOLEDs makes them more prone to degradation. Degradation host molecules layer one possible mechanisms leading luminosity loss course device operation. Although degradation are proposed literature, predicting kinetics not straightforward because evolution excited states should be accurately described....

Understanding the stability and degradation of organic light-emitting diodes (OLEDs) under working conditions is a significant area research for developing more effective OLEDs further improving their performance. However, studies processes by in situ noninvasive methods have not been adequately developed. In this work, tris-(8-hydroxyquinolino) aluminum (Alq3)-based OLED analyzed through investigation device dispersive magneto-electroluminescence (MEL(B)) response measured at room...

Band gaps in polythiophene (T) and the related polymers with a fused benzene ring (TB, polythieno[3,4-b]benzene) or pyrazine (TN, polythieno[3,4-b]pyrazine) have been computed using variety of methods. Geometries oligomers up to octamers (AM1) tetramers (B3LYP/6-31G*) optimized, while excitation energies ZINDO (INDO/S), configuration interaction singles (CIS), time-dependent density functional theory (TDDFT). extrapolated from energies. T are found nonplanar geometries, though planar form is...

The molecular parameters governing charge transport along a π-stacked fluorene chain in poly(dibenzofulvene) are studied by joint experimental and theoretical approach involving high-resolution gas-phase photoelectron spectroscopy quantum-mechanical methods. We specifically investigate the electronic couplings between moieties as well intramolecular reorganization energies, for both holes electrons. Our results indicate that favors hole over electron transport. values energies estimated here...