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Monolithic OLED-Microwire Devices for Ultrastrong Magnetic Resonant Excitation
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Novel Carbazole/Fluorene-Based Host Material for Stable and Efficient Phosphorescent OLEDs
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High Light Outcoupling Efficiency from Periodically Corrugated OLEDs
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Complete polarization of electronic spins in OLEDs
At low temperatures and high magnetic fields, electron and hole spins in an organic light-emitting diode become polarized so that recombination preferentially forms molecular triplet excited-state species. For low device currents, magnetoelectroluminescence perfectly follows Boltzmann activation, implying a virtually complete polarization outcome. As the current increases, the magnetoelectroluminescence effect is reduced because spin polarization is suppressed by the reduction in carrier residence time within the device. Under these conditions, an additional field-dependent process affecting the spin-dependent recombination emerges, possibly related to the build-up of triplet excitons and their interaction with free charge carriers. Suppression of the EL alone does not prove electronic spin polarization. We therefore probe changes in the spin statistics of recombination directly in a dual singlet-triplet emitting material, which shows a concomitant rise in phosphorescence intensity as fluorescence is suppressed. Finite spin-orbit coupling in these materials gives rise to a microscopic distribution in effective g-factors of electrons and holes, Δg, i.e., a distribution in Larmor frequencies. This Δg effect in the pair, which mixes singlet and triplet, further suppresses singlet-exciton formation at high fields in addition to thermal spin polarization of the individual carriers.
Efficient and stable single-doped white OLEDs using a palladium-based phosphorescent excimer
An efficient and stable palladium based excimer emitter was developed capable of exhibiting maximum EQE over 27% and achieved nearly 3000 h at 1000 cd m −2 .
The role of orientation in the MEL response of OLEDs
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Polymers containing isolated phenylvinyl substituted carbazole rings as electroactive materials for OLEDs
Polymers containing pendent 3-(2-phenylvinyl)carbazole moieties have been synthesized by the multi-step synthetic route. The polymers represent materials of high thermal stability with initial thermal degradation temperatures exceeding 370 °C. The glass transition temperatures of the amorphous materials were in the rage of 56–65 °C. The electron photoemission spectra of thin layers of the polymers showed ionization potentials of about 5.6 eV. Hole-transporting properties of the polymeric materials were tested in the structures of organic light emitting diodes with Alq 3 as the green emitter. The device containing hole-transporting layers of poly{9-[6-(3-methyloxetan-3-ylmethoxy)hexyl]-3-(2-phenylvinyl)carbazole} exhibited the best overall performance with a maximum photometric efficiency of about 4.0 cd/A and maximum brightness exceeding 6430 cd/m{sup 2}.
Electro-active polymers containing pendent 2,7-diarylfluorene fragments as materials for OLEDs
Poly[2-phenyl-7-(4-vinylphenyl)-9,9-diethylfluorene)], poly[2-(1-naphtyl)-7-(4-vinylphenyl)-9,9-diethylfluorene)] and poly[2-(4-biphenyl)-7-(4-vinylphenyl)-9,9-diethylfluorene)] were synthesized and characterized by NMR spectroscopy, elemental analysis and gel permeation chromatography. The derivatives represent materials of high thermal stability with initial thermal destruction temperatures from 390°C to 400 °C. The glass transition temperatures of the amorphous materials were 182 °C, 151 °C and 159 °C respectively. Hole-transporting properties of the polymeric materials were tested in the structures of organic light emitting diodes with Alq{sub 3} as the green emitter and electron transporting material. The device containing hole-transporting layers of polymer with 2-(4-biphenyl)-7-(4-vinylphenyl)-9,9-diethylfluorene moieties exhibited the best overall performance with turn on voltage of 3.6 V, a maximum photometric efficiency of 3.1 cd/A and maximum brightness of about 5300 cd/m{sup 2}.
The influence of torsion on excimer formation in bipolar host materials for blue phosphorescent OLEDs
We present a combined detailed spectroscopic and quantum chemical study on the bipolar host materials BPTRZ and MBPTRZ in solution and in neat film. In the two compounds, the hole transporting carbazole is separated from the electron transporting triazine moiety by a fully aromatic but non-conjugated meta-linked biphenyl unit. The two materials differ by an additional steric twist at the biphenyl in MBPTRZ, which is achieved by methyl-substitution in 2- and 2′-position of the biphenyl. We find that while the twist shifts the triplet state in MBPTRZ to higher energies (3.0 eV in solution) compared to BPTRZ (2.8 eV in solution), this also localizes electron density on the carbazole moiety, leading to excimer formation in neat films.
Structure of a bacterial OapB protein with its OLE RNA target gives insights into the architecture o
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Increasing the Radiative Rates of Triplet Emitters to Achieve Long-Lived and Efficient White-Emitting Organic Light Emitting Devices (OLEDs)
The objective of the project is to develop and validate white organic light emitting device WOLEDs with internal efficiencies of 100% and lifetimes exceeding a time at which the luminance drops by 30% (T 70 ) of 50,000 hr at an initial luminance of L 0 = 3000 cd/m 2 .
Pyrene-Benzimidazole Derivatives as Novel Blue Emitters for OLEDs
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SSD1351 OLED Display Driver Single Event Effects Test Report
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Bright white tandem OLED with carbon nanotube hole injecting interlayer
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Ultra High Efficiency 80 lm/W Phosphorescent White OLED Lighting Panel
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Ultrabright fluorescent OLEDS using triplet sinks
A first device is provided. The first device further comprises an organic light emitting device. The organic light emitting device further comprises an anode, a cathode, and an emissive layer disposed between the anode and the cathode. The emissive layer further comprises an organic host compound, an organic emitting compound capable of fluorescent emission at room temperature, and an organic dopant compound. The triplet energy of the dopant compound is lower than the triplet energy of the host compound. The dopant compound does not strongly absorb the fluorescent emission of the emitting compound.