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Hyperfluorescence TM , exhibiting 100% energy-to-light conversion efficiency, a sharp yet brighter emission spectrum, and excellent CIE coordinate coverage, is the ultimate 4th generation OLED technology. With our unique approach to material design and device optimization, Kyulux will provide our customers with industry leading fluorophores in all colors. Together, we will deliver unparalleled picture quality and energy efficiency to OLED display market.

4,4′-bis(N-carbazolyl)tolan (BCT) and 4,4′-bis[N-(3,6-di-t-butyl)carbazolyl]tolan (BCT-t-Bu) were synthesized as π-expanded analogs of 4,4′-bis(N-carbazolyl)biphenyl. Their photophysical characteristics both in solution and films were thoroughly investigated. Interestingly, the phosphorescence spectrum of BCT was significantly medium-dependent, and the emission maximum was red-shifted by 131 nm from 489 nm in solution at 77 K to 620 nm in a deposited film at 5 K, suggesting the presence of strong intermolecular interactions in the film. BCT and BCT-t-Bu were found to be useful as host materials for fluorescence-based organic light emitting diodes (OLEDs). However, their low triplet energy levels in films negated their potential to act as hosts in phosphorescence-based OLEDs.

Porphycene was covalently immobilized in a sol–gel silica film deposited on a glass plate, and the immobilized porphycene showed a photosensitizing property with recycling for the photo-oxidation of 1,5-dihydroxynaphthalene.

A dewetting process of an evaporating solution is used to form micrometer-sized amorphous droplets, or domes, of the low molar mass solute on substrates such as silicon, mica, glass, and indium-tin-oxide. Using dewetting, the organic hole transporting material of organic light emitting diodes was patterened into micrometer-sized domes on an indium-tin-oxide electrode. Annealing led to a structural change of the domes, which was investigated by optical and electron microscopes. The dewetted dome samples were then coated with electron transport material and top electrode to give functioning organic light emitting diodes devices.

筆者らは, 青色リン光材料をゲスト分子として用いた有機EL素子において, 高効率青色発光を得るためにπ共役系の短いシロキサン化合物であるHexaphenylcyclotri siloxane (DPSiO3) をホスト材料として試みた. この材料をEPA溶液に溶解し, T=77Kにおいてリン光スペクトルを測定したところ, DPSiO3のリン光スペクトルはベンゼンのリン光スペクトルとほぼ同じ波長領域 (λonset～350nm) に観測され, これらの化合物は本質的にベンゼン環にπ電子系が局在していることが示唆された. Iridium (III) bis (4,6-di-fluorophenyl) -pyridinato-N, C2) picolinate (FIrpic) をゲスト分子としたEL素子において, DPSiO3をホストとした素子では最大ηext=11.1%の外部EL量子効率を得ることができた.

We studied the photoluminescence (PL) characteristics of the red phosphor tris(2-phenylquinoline)iridium(III) (Ir(phq)3) doped into an Ir complex host layer. Although we expect efficient triplet exciton confinement by the host Ir complexes because of their triplet energy level being higher than that of Ir(phq)3, we observed a rather low PL quantum efficiency. We clarified that the short Forster energy transfer distance in the host layers resulted in limited energy transfer between host and guest molecules.

We compared the photoluminescence efficiency (ΦPL) of fac-tris(2-phenylpyridine)iridium (Ir(ppy)3) and derivatives of it in solution and in doped solid-state films and estimated their radiative and nonradiative decay rates. The green phosphor of Ir(ppy)3 and blue phosphors of FIrpic, Ir(Fppy)3, FIr6 showed high ΦPL values approaching to 100% in both solution and doped solid-state films. On the other hand, the red phosphor of Btp2Ir(acac) showed lower ΦPL value less than 40% in both environments. Photoacoustic spectroscopy results indicated that for Btp2Ir(acac) nonradiative decay from the triplet state to the ground states is 64 ± 8%.

A material possessing a very small energy gap between its singlet and triplet excited states, ΔE1−3, which allows efficient up-conversion of triplet excitons into a singlet state and leads to efficient thermally activated delayed fluorescence (TADF), is reported. The compound, 2-biphenyl-4,6-bis(12-phenylindolo[2,3-a] carbazole-11-yl)-1,3,5-triazine, breaks the restriction of a large energy gap, with a ΔE1−3 of just 0.11 eV, while maintaining a high fluorescent radiative decay rate (kr∼107). The intense TADF provides a pathway for highly efficient electroluminescence.

Small molecule organic light-emitting diodes (SM-OLEDs) are efficient large area light sources facing their market entry. However, a low light outcoupling efficiency of typically 20% still strongly limits device performance. Here, we highlight the potential of employing dye-doped emission layers with emitting molecules having horizontally oriented transition dipole moments. The effect of molecular orientation is explained by studying optical simulations that distinguish between horizontal and vertical dipole orientation. In addition, an experimental method that enables straightforward determination of dipole orientation in guest–host systems is presented and used for the analysis of two materials that are very similar except for their orientation. By measuring the external electroluminescence quantum efficiency of SM-OLEDs based on these materials, evidence is found that a mainly horizontal dipole orientation enhances light outcoupling by around 45%. Furthermore, the effect of orientation in SM-OLEDs offers many additional benefits concerning stack design and has fundamental implications for material choice.

We have developed an apparatus (Hamamatsu C9920-02) for measuring the absolute photoluminescence quantum yield. This system consists of an excitation light source, a sample holder mounted in an integrating sphere and a multi-channel CCD spectrometer. Using this apparatus, the absolute phosphorescence quantum yields were measured for several iridium complexes doped in organic thin films or dissolved in deaerated solutions. The iridium complexes fac-tris(2phenylpyridine)iridium(III) (Ir(ppy)3) and its derivatives, showed high phosphorescence quantum yields (>90 %), while bis(2-(2’-benzo(4,5-a)thienyl)pyridinato-N,C 3’ )iridium(III)(acetylacetonate) (Btp2Ir(acac)) gave a lower phosphorescence quantum yield (less than 40 %). To reveal the mechanism of nonradiative decay of the excited iridium complexes, we made time-resolved photoacoustic measurements. It was found that all of the iridium complexes undergo S1-T1 intersystem crossing with efficiencies of close to 100 % after photoexcitation. This indicates that the lower phosphorescence quantum yield for Btp2Ir(acac) is due to involvement of the T1-S0 intersystem crossing process.

A heavy atom, bromine, was directly substituted into the porphycene macrocycle to promote intersystem crossing by way of spin-orbit coupling. The singlet oxygen production ability of the porphycene is dramatically enhanced, and the highest value of 0.95 for the quantum yield of singlet oxygen generation (PhiDelta) was obtained for the dibrominated porphycene by visible light excitation.

A dewetting process of an evaporating solution is used to form micrometer-sized amorphous droplets, or domes, of the low molar mass solute on substrates such as silicon, mica, glass, and indium-tin-oxide. Using dewetting, the organic hole transporting material of organic light emitting diodes was patterened into micrometer-sized domes on an indium-tin-oxide electrode. Annealing led to a structural change of the domes, which was investigated by optical and electron microscopies. The dewetted dome samples were then coated with electron transport material and top electrode to give functioning organic light emitting diodes. Microscope imaging reveals a strong luminescence from the micrometer-sized domes.

The photophysical properties and photooxidation ability of the β-sulfonatoporphycenes are reported. The photophysical parameters depend on the number of substitutions. The disulfonated porphycene 2...

The photoluminescence, i.e., fluorescence and phosphorescence, characteristics of host materials with wide energy gaps suitable for phosphorescence-based organic light-emitting diodes (OLEDs) are summarized. In the vacuum deposited films, the host materials show phosphorescent emission in the blue to green region and triplet energy levels of E T = 2.6–3.1 eV because of the presence of steric hindrance. An OLED containing 1,2,3,4-tetraphenyl-5-(3-pyridyl)benzene as a host and iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,C 2]picolinate as a blue emissive phosphorescent dopant exhibits an external electroluminescence efficiency of ∼12%.

The red-emitting phosphorescent organic light-emitting device employing Bis[2-(2-benzothiazoyl)phenolato]zinc(II) (Zn(BTP)2) as a host material has been demonstrated. The device generates saturated red emission with Commission Internationale de l’Eclairage coordinates of (0.67, 0.33), characterized by a low driving voltage of 3.2V and high external quantum efficiency of 10.3% at 10mA∕cm2. Moreover, the efficiency and lifetime are improved by using 30% NPB-doped Zn(BTP)2 host in the emitting layer, where NPB is 4,4′-bis(N-phenyl-1-naphthyl-amino)biphenyl. The maximum external quantum efficiency of the device reaches 12.6% at 1.7mA∕cm2. The device has exhibited excellent stability. The half-luminance lifetime is 240h at 80mA∕cm2 (initial luminance of 6070cd∕m2). The relationship between the employed host material and device performance is discussed.