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The inherent flexibility afforded by molecular design has accelerated the development of a wide variety of organic semiconductors over the past two decades. In particular, great advances have been made [...]

Purpose: We aimed to develop a reliable identification algorithm combining diagnostic codes with several treatment factors for inpatients with acute ischemic stroke (AIS) to conduct pharmacoepidemiological studies using the administrative database MID‐NET® in Japan. Methods: We validated 11 identification algorithms based on 56 different diagnostic codes (International Classification of Diseases, Tenth Revision; ICD‐10) using Diagnosis Procedure Combination (DPC) data combined with information on AIS therapeutic procedures added as "AND" condition or "OR" condition. The target population for this study was 366 randomly selected hospitalized patients with possible cases of AIS, defined as relevant ICD‐10 codes and diagnostic imaging and prescription or surgical procedure, in three institutions between April 1, 2015 and March 31, 2017. We determined the positive predictive values (PPVs) of these identification algorithms based on comparisons with a gold standard consisting of chart reviews by experienced specialist physicians. Additionally, the sensitivities of them among 166 patients with the possible cases of AIS at a single institution were evaluated. Results: The PPVs were 0.618 (95% confidence interval [CI]: 0.566–0.667) to 0.909 (95% CI: 0.708–0.989) and progressively increased with adding or limiting information on AIS therapeutic procedures as "AND" condition in the identification algorithms. The PPVs for identification algorithms based on diagnostic codes I63.x were >0.8. However, the sensitivities progressively decreased to a maximum of ~0.2 after adding information on AIS therapeutic procedures as "AND" condition. Conclusions: The identification algorithms based on the combination of appropriate ICD‐10 diagnostic codes in DPC data and other AIS treatment factors may be useful to studies for AIS at a national level using MID‐NET®. [ABSTRACT FROM AUTHOR]

The development of efficient metal-free organic emitters with thermally activated delayed fluorescence (TADF) properties for deep-blue emission is still challenging. A new family of deep-blue TADF emitters based on a donor-acceptor architecture has been developed. The electronic interaction between donor and acceptor plays a key role in the TADF mechanism. Deep-blue OLEDs fabricated with these TADF emitters achieved high external quantum efficiencies over 19.2 % with CIE coordinates of (0.148, 0.098). [ABSTRACT FROM AUTHOR]

Aim To develop a population pharmacodynamic (PPD) model describing the time course for the hemoglobin A1c (HbA1c)-lowering effects of adding treatment of DPP-4 inhibitors and to assess the efficacy of combination therapy in type 2 diabetes mellitus patients based on electronic medical records. Methods Information on patients was collected retrospectively from electronic medical records. Of the 4 DPP-4 inhibitors used, we focused on sitagliptin as it had the best time-response relationships. A physiological indirect response model was developed to describe changes in HbA1c levels. Results An indirect response model, based on the 1300 HbA1c levels of 160 patients, described the time course for the HbA1c-lowering effects of adding sitagliptin. The combination with pioglitazone decreased the HbA1c synthesis rate by 7.74% relative to without pioglitazone. Bayesian forecasting based on the final PDD model using the first two HbA1c observations, before and within 30 days after the addition of sitagliptin, gave a precise prediction of HbA1c-lowering effects individually. Conclusions Our PPD model quantitatively described the beneficial effects of combination therapy with pioglitazone and sitagliptin. The proposal methodology is also expected to be applicable to other medicines based on electronic medical records in clinical practice. [ABSTRACT FROM AUTHOR]

Much effort has been devoted to developing highly efficient organic light-emitting diodes (OLEDs) that function through phosphorescence or thermally activated delayed fluorescence (TADF). However, efficient host materials for blue TADF and phosphorescent guest emitters are limited because of their requirement of high triplet energy levels. Herein, we report the rigid acceptor unit benzimidazobenzothiazole (BID-BT), which is suitable for use in bipolar hosts in blue OLEDs. The designed host materials, based on BID-BT, possess high triplet energy and bipolar carrier transport ability. Both blue TADF and phosphorescent OLEDs containing BID-BT-based derivatives exhibit external quantum efficiencies as high as 20 %, indicating that these hosts allow efficient triplet exciton confinement appropriate for blue TADF and phosphorescent guest emitters. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) emitters are third-generation electroluminescent materials that realize highly efficient organic light-emitting diodes (OLEDs) without using rare metals. Here, after briefly reviewing the principles of TADF and its use in OLEDs, we report a sky-blue TADF emitter, 9-(4-(benzo[ d]thiazol-2-yl)phenyl)- N3, N3, N6, N6-tetraphenyl-9 H-carbazole-3,6-diamine (DAC-BTZ). DAC-BTZ is a purely organic donor-acceptor-type molecule with a small energy difference between its lowest excited singlet state and lowest triplet state of 0.18-0.22 eV according to fluorescence and phosphorescence spectra of a DAC-BTZ-doped film. In addition, the doped film exhibits a high photoluminescence quantum yield of 0.82. Time-resolved photoluminescence measurements of the doped film confirm that DAC-BTZ emits TADF. An OLED containing DAC-BTZ as an emitter exhibits a maximum external quantum efficiency (EQE) of 10.3%, which exceeds those obtained with conventional fluorescent emitters (5-7.5%). TADF from DAC-BTZ makes a large contribution to the high EQE of its OLED. [ABSTRACT FROM AUTHOR]

Organic compounds that exhibit highly efficient, stable blue emission are required to realize inexpensive organic light-emitting diodes for future displays and lighting applications. Here, we define the design rules for increasing the electroluminescence efficiency of blue-emitting organic molecules that exhibit thermally activated delayed fluorescence. We show that a large delocalization of the highest occupied molecular orbital and lowest unoccupied molecular orbital in these charge-transfer compounds enhances the rate of radiative decay considerably by inducing a large oscillator strength even when there is a small overlap between the two wavefunctions. A compound based on our design principles exhibited a high rate of fluorescence decay and efficient up-conversion of triplet excitons into singlet excited states, leading to both photoluminescence and internal electroluminescence quantum yields of nearly 100%. [ABSTRACT FROM AUTHOR]

Metal complexes emitting thermally activated delayed fluorescence based on intra-ligand charge transfer and enhanced by metallization were synthesized. Organic light-emitting diodes using a thermally stable zinc complex processed by vacuum vapor deposition achieved an external quantum efficiency of nearly 20%. [ABSTRACT FROM AUTHOR]

Organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) have emerged as cheaper alternatives to high-performance phosphorescent OLEDs with noble-metal-based dopants. However, the efficiencies of blue TADF OLEDs are still low at high luminance, limiting full-colour display. Here, we report a blue OLED containing a 9,10-dihydroacridine/diphenylsulphone derivative that has a comparable performance to today's best phosphorescent OLEDs. The device offers an external quantum efficiency of 19.5% and reduced efficiency roll-off characteristics at high luminance. Through computational simulation, we identified six pretwisted intramolecular charge-transfer (CT) molecules with small singlet-triplet CT state splitting but different energy relationships between 3CT and locally excited triplet (3LE) states. Systematic comparison of their excited-state dynamics revealed that CT molecules with a large twist angle can emit efficient and short-lifetime (a few microseconds) TADF when the emission peak energy is high enough and the 3LE state is higher than the 3CT state. [ABSTRACT FROM AUTHOR]

The efficiency roll-off characteristicsin highly efficient thermallyactivated delayed fluorescence (TADF) based organic light-emittingdiodes (OLEDs) were effectively suppressed by controlling the molecularorientation of a 4,4′-bis(N-carbazolyl)-1,1′-biphenyl(CBP) host matrix. The hole mobility in the light emitting layer wasfound to govern the magnitude of this suppression. Three-dimensionalfinite-difference time-domain calculations and photoluminescence quantumyield measurements revealed that the optical characteristics of thefabricated devices and photophysical properties of the TADF emitterdid not affect efficiency roll-off. CBP molecules adopted random orientationswhen films were fabricated at high temperature (350 K), resultingin low hole mobility, and shifting the recombination zone away fromthe interface of the emitting layer with the electron transportinglayer. When CBP was randomly orientated, efficiency roll-off was suppressedby 30% at a current density of 100 mA cm–2. Thisresult indicates that control of the molecular orientation of thehost can allow us to indirectly tune the carrier balance in OLEDs. [ABSTRACT FROM AUTHOR]

We developed highly-efficient thermally activated delayed fluorescence (TADF) emitters containing 2,5-diphenyl-1,3,4-oxadiazole (OXD) or 3,4,5-triphenyl-4H-1,2,4-triazole (TAZ) electron acceptor and phenoxazine (PXZ) electron donor moieties. Oxadiazole-based compounds PXZ-OXD and 2PXZ-OXD showed green emission, while the triazole-based ones PXZ-TAZ and 2PXZ-TAZ exhibited sky-blue emission. In toluene solution, the donor–acceptor–donor-type molecules 2PXZ-OXD and 2PXZ-TAZ showed more efficient TADF and higher photoluminescence quantum yields (PLQYs) than the donor–acceptor-type molecules PXZ-OXD and PXZ-TAZ. When doped into a host material, 2PXZ-OXD displayed a high PLQY of 87%. An organic light-emitting diode using 2PXZ-OXD as an emitter exhibited an external quantum efficiency (EQE) of 14.9%, which exceeds those obtained with conventional fluorescent emitters. This high EQE results from the efficient generation of TADF in 2PXZ-OXD. [ABSTRACT FROM AUTHOR]

Dynamic light scattering (DLS) is a well-known technique for measuring the size of nanoparticles from the diffusion coefficient. We developed a new DLS technique with high sensitivity and used it as a detection tool in microchemical applications. We found a step-like downward change in the diffusion coefficient of nanoparticles just by starting a slight flow in the fluid channel. Because the diffusion coefficient is defined by the ratio of the force due to the chemical potential gradient to the frictional coefficient for the particle by a solvent, we propose that the frictional coefficient increased significantly. This result suggests that nanoscale friction under liquid motion differs from that under a steady state. [ABSTRACT FROM AUTHOR]

Efficient thermally activated delayed fluorescence was observed from a spiro-anthracenone derivative (ACRSA). An organic light-emitting diode containing ACRSA exhibited blue-greenish electroluminescence with a maximum external quantum efficiency of 16.5%. [ABSTRACT FROM AUTHOR]

We demonstrate that horizontally oriented organic semiconducting molecules in amorphous films can be oriented uniaxially by mechanical brushing. The absorption of polarized light in the direction parallel to the brushing direction was higher than the absorption in the perpendicular direction. Thus, simultaneous uniaxial and in-plane molecular orientation in amorphous films was realized by brushing. In addition, we demonstrate a polarized electroluminescence from the films treated by mechanical brushing. [ABSTRACT FROM AUTHOR]

A correction to the article related to synthesis of benzimidazobenzothiazole that was published in a previous issue is presented.

We have designed and synthesized a high-efficiency purely organic luminescent material, 2,4-bis{3-(9 H-carbazol-9-yl)-9 H-carbazol-9-yl}-6-phenyl-1,3,5-triazine (CC2TA) comprising the bicarbazole donor and phenyltriazine acceptor units, which is capable of emitting thermally activated delayed fluorescence. The molecular design of CC2TA allows spatial separation of HOMO and LUMO on the donor and acceptor fragments, respectively, leading to an exceptionally small singlet-triplet exchange energy (ΔEST = 0.06 eV) together with a high triplet energy. Furthermore, a high external electroluminescence quantum efficiency as high as 11% ± 1% has been achieved in the sky-blue organic light-emitting diodes employing CC2TA as an emitter. [ABSTRACT FROM AUTHOR]