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All inorganic perovskites quantum dots (PeQDs) have attracted much attention for used in thin film display applications and solid-state lighting applications, owing to their narrow band emission with high photoluminescence quantum yields (PLQYs), color tunability, and solution processability. Here, we fabricated low-driving-voltage and high-efficiency CsPbBr PeQDs light-emitting devices (PeQD-LEDs) using a PeQDs washing process with an ester solvent containing butyl acetate (AcOBu) to remove excess ligands from the PeQDs. The CsPbBr PeQDs film washed with AcOBu exhibited a PLQY of 42%, and a narrow PL emission with a full width at half-maximum of 19 nm. We also demonstrated energy level alignment of the PeQD-LED in order to achieve effective hole injection into PeQDs from the adjacent hole injection layer. The PeQD-LED with AcOBu-washed PeQDs exhibited a maximum power efficiency of 31.7 lm W and EQE of 8.73%. Control of the interfacial PeQDs through ligand removal and energy level alignment in the device structure are promising methods for obtaining high PLQYs in film state and high device efficiency.

Cesium lead halide (CsPbX, X = Cl, Br, or I) perovskite quantum dots (QDs) are known as ionic nanocrystals, and their optical properties are greatly affected by the washing solvent used during the purification process. Here, we demonstrate the purification process of CsPbBr perovskite QDs using low-dielectric-constant solvents to completely remove impurities, such as the reaction solvent and desorbed ligands. The use of the ether solvent diethylene glycol dimethyl ether (diglyme), having a low dielectric constant of ε = 7.23, as a poor solvent for reprecipitation allowed for multiple wash cycles, which led to high purity and high photoluminescence quantum yield for CsPbBr QDs. The light-emitting device constructed with the CsPbBr QDs and washed twice with diglyme (two-wash) showed a low turn-on voltage of 2.7 V and a peak external quantum efficiency of over 8%. Thus, the purification of perovskite QDs with multiple wash cycles using a low-dielectric-constant solvent is an effective approach for enhancing not only the optical properties but also the efficiency of perovskite quantum dot light-emitting devices.

AKATSUKI is the Japanese Venus Climate Orbiter that was designed to investigate the climate system of Venus. The orbiter was launched on May 21, 2010, and it reached Venus on December 7, 2010. Thrust was applied by the orbital maneuver engine in an attempt to put AKATSUKI into a westward equatorial orbit around Venus with a 30-h orbital period. However, this operation failed because of a malfunction in the propulsion system. After this failure, the spacecraft orbited the Sun for 5 years. On December 7, 2015, AKATSUKI once again approached Venus and the Venus orbit insertion was successful, whereby a westward equatorial orbit with apoapsis of ~440,000 km and orbital period of 14 days was initiated. Now that AKATSUKI's long journey to Venus has ended, it will provide scientific data on the Venusian climate system for two or more years. For the purpose of both decreasing the apoapsis altitude and avoiding a long eclipse during the orbit, a trim maneuver was performed at the first periapsis. The apoapsis altitude is now ~360,000 km with a periapsis altitude of 1000-8000 km, and the period is 10 days and 12 h. In this paper, we describe the details of the Venus orbit insertion-revenge 1 (VOI-R1) and the new orbit, the expected scientific information to be obtained at this orbit, and the Venus images captured by the onboard 1-µm infrared camera, ultraviolet imager, and long-wave infrared camera 2 h after the successful initiation of the VOI-R1.

SUMMARY Earthquake swarms in the area east of the Izu Peninsula, Central Japan have been active and have been repeated intermittently since 1978 after 40 years of quiescence. The activities were always accompanied by crustal deformations, which were well modelled by dyke intrusions. To study the process of a dyke intrusion, precise hypocentres of the latest activity occurring in 1998 are obtained in this paper using waveform similarity, by which new images of volcanic processes have been successfully acquired at several volcanoes. The relocated hypocentres are mainly aligned on a thin vertical plane with a circular shape at a depth of 3–7 km, and there is an aseismic area at the centre. The normal direction to the plane coincides well with the direction of tectonic extensional stress around the hypocentral area and matches theoretical models well. At the beginning of the activity, a small fraction of the events occurred at greater depth, where hypocentres align on a vertical line and migrate upward at a rate of 1 km h−1. The migration rate in this stage agrees well with a theoretical model of buoyancy‐driven dyke propagation. After 1 day from the beginning, earthquakes began to occur around the aseismic area, and hypocentres spread on the thin circular plane described above. During this activity, the hypocentres seemed to migrate downwards and upwards from the centre. The earthquakes are caused by shear fracture at the tip of the dyke and the migration of hypocentres reflects that the dyke expands downward and upward from the neutrally buoyant layer that is located at the centre of the swarm. In this paper, we also propose a process of magma intrusion based on the precise migration of hypocentres, and show that the 1998 activity is composed of a few simple volcanic processes: magma rising by buoyancy, it staying at a neutral buoyancy point and spreading outward from the neutral point with elastic fracture by an inside excess magma pressure.

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[1] A series of earthquake swarms off the east coast of Izu Peninsula, central Japan, is typically associated with dike intrusion around active volcanoes. Numerous studies in this region have documented the seismic activity and ground deformations without fully resolving the process of dike intrusion. This study involves a joint analysis of geodetic and seismic data from the most recent major activity in this region, occurring in 1998, to reveal the process of dike intrusion quantitatively. We combine data from a dense GPS array, including 10 temporary stations, with seismic analysis published previously. We estimate the location of the dikes from seismic data and the volume of intruded magma from geodetic data. Combined analysis of both data sets enables us to reveal the kinematic process of dike intrusion associated with the 1998 earthquake swarm. The process of dike intrusion is quantitatively modeled using the time evolution of recorded dike volume and the use of seismic hypocenters as an indicator of the site of instantaneous dike intrusion. On the basis of these observations, we propose the following process of the dike intrusion: The magma rose upward through a pathway aligned vertically and created a dike when it lost buoyancy. We also evaluate the dike intrusion process quantitatively using a model of a circular dike that grows under a continuous magma supply from a deep magma reservoir. From the observational data, we infer the time evolution in the dike shape, pressure distribution, and magma viscosity in the dike. The acquired viscosity increases over time and it may be reasonable because magma cools gradually. However, its value is too large compared to typical basaltic magma expected in this region. It may represent magma within the dike that is nearly solidified. Otherwise, the magma is supplied intermittently and the dike growth is mainly controlled by the magma supply rate from a deep reservoir. The quantitative description of the dike intrusion process in nature described in this study is very rare, and our results provide constraints on several parameters that have not been solved in many previous theoretical studies on the dike intrusion process.Citation: Morita, Y., S. Nakao, and Y. Hayashi (2006), A quantitative approach to the dike intrusion process inferred from a joint analysis of geodetic and seismological data for the 1998 earthquake swarm off the east coast of Izu Peninsula, central Japan,

A lot of research, mostly using electron-injection layers (EILs) composed of alkali-metal compounds has been reported with a view to increase the efficiency of solution-processed organic light-emitting devices (OLEDs). However, these materials have intractable properties, such as a strong affinity for moisture, which cause the degradation of OLEDs. Consequently, optimal EIL materials should exhibit high electron-injection efficiency as well as be stable in air. In this study, polymer light-emitting devices (PLEDs) based on the commonly used yellow-fluorescence-emitting polymer F8BT, which utilize poly(diallyldimethylammonium)-based polymeric ionic liquids, are experimentally and analytically investigated. As a result, the optimized PLED employing an EIL comprising poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (poly(DDA)TFSI), which is expected to display good moisture resistance because of water repellency of fluorocarbon groups, exhibits excellent storage stability in air and electroluminescence performance with a low turn-on voltage of 2.01 V, maximum external quantum efficiency of 9.00%, current efficiency of 30.1 cd A , and power efficiency of 32.4 lm W . The devices with poly(DDA)TFSI show one of the highest efficiencies as compared to the reported standard PLEDs. Moreover, poly(DDA)TFSI is applied as a hole-injection layer (HIL). The optimized PLED using poly(DDA)TFSI as the HIL exhibits performances comparable to those of a device that uses a conventional poly(3,4-ethylenedioxy-thiophene):poly(4-styrenesulfonate) HIL.