Thermally activated delayed fluorescence (TADF) materials based on the multiple resonance (MR) effect are applied in organic light‐emitting diodes (OLEDs), combining high color purity and efficiency. However, they are not fabricated via solution‐processing, which is an economical approach toward the mass production of OLED displays. Here, a solution‐processable MR‐TADF material (OAB‐ABP‐1), with an extended π‐skeleton and bulky substituents, is designed. OAB‐ABP‐1 is synthesized from commercially available starting materials via a four‐step process involving one‐shot double borylation. OAB‐ABP‐1 presents attractive photophysical properties, a narrow emission band, a high photoluminescence quantum yield, a small energy gap between S1 and T1, and low activation energy for reverse intersystem crossing. These properties are attributed to the alternating localization of the highest occupied and lowest unoccupied molecular orbitals induced by the boron, nitrogen, and oxygen atoms. Furthermore, to facilitate charge recombination, two novel semiconducting polymers with similar ionization potentials to that of OAB‐ABP‐1 are synthesized for use as interlayer and emissive layer materials. A solution‐processed OLED device is fabricated using OAB‐ABP‐1 and the aforementioned polymers; it exhibits pure green electroluminescence with a small full‐width at half‐maximum and a high external quantum efficiency with minimum efficiency roll‐off.

An expanded heterohelicene consisting of three BN 2 -embedded [4]helicene subunits (V-DABNA-Mes) has been synthesized by one-shot triple borylation. The key to success is the excessive use of boron tribromide in an autoclave. Based on the multiple resonance effect of three boron and six nitrogen atoms, V-DABNA-Mes exhibited a narrowband sky-blue thermally activated delayed fluorescence with a full width at half-maximum of 16 nm. The resonating π-extension minimized the singlet−triplet energy gap and enabled rapid reverse intersystem crossing with a rate constant of 4.4 × 10 5 s −1 . The solution-processed organic lightemitting diode device, employed as an emitter, exhibited a narrowband emission at 480 nm with a high external quantum efficiency of 22.9%.

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[1] We report on nighttime medium-scale traveling ionospheric disturbances (MSTIDs) observed at Kototabang, Indonesia (geographic longitude: 100.3 E; geographic latitude: 0.2 S; and geomagnetic latitude: 10.6 S) during a 7-year period from October 2002 to October 2009. MSTIDs were observed in 630-nm nighttime airglow images by using a highly sensitive all-sky airglow imager at Kototabang. The averages and standard deviations of horizontal phase velocity, period, and horizontal wavelength of MSTIDs observed during the 7 years were 320 AE 170 m/s, 42 AE 11 min, and 790 AE 440 km, respectively. The occurrence rate of the observed MSTIDs decreased with decreasing solar activity. The average horizontal wavelength of MSTIDs increased with decreasing solar activity. Southward MSTIDs were dominant throughout the 7 years of observations. These facts are consistent with the hypothesis that the observed MSTIDs are caused by gravity waves in the thermosphere. Moreover, we compared the propagation directions of the observed MSTIDs with the locations of tropospheric convection activity for the events where gravity waves producing the observed MSTIDs could have existed in the lower atmosphere. Strong tropospheric convection was found within AE30 degrees from the source directions of MSTIDs in 81% of the MSTID events. In such events, gravity waves were possibly generated from deep convection in the troposphere and directly propagated into the thermosphere.

This is the first paper that reports simultaneous observations of zonal drift of plasma bubbles and the thermospheric neutral winds at geomagnetically conjugate points in both hemispheres. The plasma bubbles were observed in the 630 nm nighttime airglow images taken by using highly sensitive all-sky airglow imagers at Kototabang, Indonesia (geomagnetic latitude (MLAT): 10.0• S), and Chiang Mai, Thailand (MLAT: 8.9• N), which are nearly geomagnetically conjugate stations, for 7 h from 13 to 20 UT (from 20 to 03 LT) on 5 April 2011. The bubbles continuously propagated eastward with velocities of 100-125 m/s. The 630 nm images at Chiang Mai and those mapped to the conjugate point of Kototabang fit very well, which indicates that the observed plasma bubbles were geomagnetically connected. The eastward thermospheric neutral winds measured by two Fabry-Perot interferometers were 70-130 m/s at Kototabang and 50-90 m/s at Chiang Mai. We compared the observed plasma bubble drift velocity with the velocity calculated from the observed neutral winds and the model conductivity, to investigate the F region dynamo contribution to the bubble drift velocity. The estimated drift velocities were 60-90% of the observed velocities of the plasma bubbles, suggesting that most of the plasma bubble velocity can be explained by the F region dynamo effect.