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排序方式: 共有218条查询结果,搜索用时 15 毫秒
211.
JY Hu YJ Pu G Nakata S Kawata H Sasabe J Kido 《Chemical communications (Cambridge, England)》2012,48(67):8434-8436
A pyrene-containing single-molecule excimer-emitting compound, 1,8-bis(pyren-2-yl)naphthalene (BPyN), was synthesized. With BPyN as a host emitter, C545T-based green OLEDs were fabricated, exhibiting high efficiencies of 22 lm W(-1), 22 cd A(-1) and 6.2% external quantum efficiency (EQE) at 100 cd m(-2), and 19 lm W(-1), 22 cd A(-1) and 6.2% EQE at 1000 cd m(-2). 相似文献
212.
Koichi Sato Tadashi Takamasu Giyuu Kido 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):305
On AlAs:Yb/GaAs superlattice samples, we measured photoluminescence (PL) spectra including their temperature dependence, magnetic field dependence and resistance up to 25 T. In case of selective excitation of well layers, two broad band PLs were observed in additional to the exception of intra-4f PL from Yb. These peaks show oscillatory behavior similar to that of two-dimensional electron system. From the periods of the oscillation, the electron densities are estimated of the order of which are cannot be archived by usual photoexcitation. It was found that the electron density shows a linear dependence on the excitation energy. To explain such distinctive phenomena, we proposed a new model where Yb ions form hole traps in AlAs. 相似文献
213.
Takamasa Hashimoto Koji Kido Shintaro Kaki Takehiro Yamamoto Noriyasu Mori 《Rheologica Acta》2006,45(6):841-852
Dynamic viscoelasticities and flow properties were measured for aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) to examine the effects of surfactant (C
D) and salt (C
S). The relaxation time λ of a single mode Maxwell model was obtained, and the relationship between λ and free NaSal concentration was discussed. The relation between λ and was applied to the classification of flow curves, which were obtained using a capillary rheometer. In the flow curves, a shear rate jump occurred at low shear rates for the solutions with low , while bending was seen at high shear rates for all the flow curves. On the other hand, vortex growth at the salient corner in the entrance region of the capillary was also investigated. Four different flow patterns were identified: Newtonian-like flow (A), steady vortex flow (B), periodically oscillated flow (C), and perfectly unstable flow (D). In the steady vortex of the flow pattern B, the vortex length increased with increasing shear rate. In the flow patterns C and D, white turbidity was observed. Furthermore, the relation between λ and was also applied to the discussion on the development of the vortex. 相似文献
214.
Hideki Taguchi Kazuhiro Hirata Hiroyasu Kido Yasuo Takeda Masaki Kato Ken Hirota 《Solid State Sciences》2009,11(7):1222-1225
Orthorhombic distorted K2NiF4-type (Ca1+xNd1?x)CrO4 (0.00 ≤ x ≤ 0.15) was synthesized using a standard ceramic technique. The cell parameters (a and c) decreased, whereas the cell parameter (b) increased with the increase in x. The variation in the global instability index (GII) indicated that the crystal stability of (Ca1+xNd1?x)CrO4 was not influenced by the Cr4+ ion content. At all temperatures, the electrical conductivity (σ) of (Ca1+xNd1?x)CrO4 increased with the increase in x. (Ca1+xNd1?x)CrO4 was a p-type semiconductor and exhibited hopping conductivity in a small-polaron model in the temperature range of 290 K ≤ T ≤ 713 K. The Cr4+ ion acts as an acceptor, and the electron transfer through the Cr3+–O–Cr4+ path becomes active as a result of the Cr4+ ion content and the Cr–O(1) distance. 相似文献
215.
Ayato Arai Prof. Hisahiro Sasabe Kohei Nakao Yuki Masuda Prof. Junji Kido 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(15):4971-4976
High-performance organic light-emitting diodes (OLEDs) that use phosphorescent and/or thermally activated delayed fluorescence emitters are capable of realizing 100 % electron-to-photon conversion. The host materials in these OLEDs play crucial roles in determining OLED performance. Carbazole derivatives are frequently used as host materials, among which 3,3-bis(9H-carbazol-9-yl)biphenyl ( mCBP ) is often used for lifetime testing in scientific studies. In this study, the π conjugation of the carbazole unit was expanded to enhance OLED lifetime by designing and developing two benzothienocarbazole (BTCz)-based host materials, namely m1BTCBP and m4BTCBP . Among these host materials, m1BTCBP formed a highly efficient [Ir(ppy)3]-based OLED with an operational luminescence half-life (LT50) of over 300 h at an initial luminance of approximately 12000 cd m−2 (current density: 25 mA cm−2). The LT50 value at 1000 cd cm−2 was estimated to be about 23 000 h. This performance is clearly higher than that of mCBP -based OLEDs (LT50≈8500 h). 相似文献
216.
Hiroki Arai Prof. Hisahiro Sasabe Hisaki Tsuneyama Kengo Kumada Prof. Junji Kido 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(42):10869-10874
Recently, researchers have focused on thermally activated delayed fluorescence (TADF) for efficient future lighting and displays. Among TADF emitters, a combination of triazine and acridine is a promising candidate for realizing high-efficiency organic light-emitting devices (OLEDs). However, simultaneous development of perfect horizontal orientation (Θ=100 %) and an external quantum efficiency (EQE) of over 40 % is still challenging. Here, to obtain insights for further improvements of a triazine/acridine combination, various asymmetric spirobiacridine (SBA)-based TADF emitters with a unity photoluminescence quantum yield and high Θ ratio of over 80 % were developed. Furthermore, the substitution effects of the triazine acceptor unit on the photophysical properties were studied, including molecular orientations and OLED performance. The corresponding OLED exhibited sky-blue emission with a high EQE of over 30 %. 相似文献
217.
Natsuo Nagamura Prof. Hisahiro Sasabe Hiroki Sato Nozomi Ito Shoki Abe Dr. Yoshihito Sukegawa Prof. Daisuke Yokoyama Prof. Hironori Kaji Prof. Junji Kido 《Chemistry (Weinheim an der Bergstrasse, Germany)》2023,29(1):e202202636
Using a tailored high triplet energy hole transport layer (HTL) is a suitable way to improve the efficiency and extend the lifetime of organic light-emitting devices (OLEDs), which can use all molecular excitons of singlets and triplets. In this study, dibenzofuran (DBF)-end-capped and spirobifluorene (SBF) core-based HTLs referred as TDBFSBF1 and TDBFSBF2 were effectively developed. TDBFSBF1 exhibited a high glass transition temperature of 178 °C and triplet energy of 2.5 eV. Moreover, a high external quantum efficiency of 22.0 %, long operational lifetime at 50 % of the initial luminance of 89,000 h, and low driving voltage at 1000 cd m−2 of 2.95 V were achieved in green phosphorescent OLEDs using TDBFSBF1 . Further, a high-hole mobility μh value of 1.9×10−3 cm2 V−1 s−1 was recorded in TDBFSBF2 . A multiscale simulation successfully reproduced the experimental μh values and indicated that the reorganization energy was the primary factor in determining the mobility differences among these SBF core based HTLs. 相似文献
218.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献