Highly efficient non-doped blue fluorescent OLEDs with low efficiency roll-off based on hybridized local and charge transfer excited state emitters

Designing a donor–acceptor (D–A) molecule with a hybridized local and charge transfer (HLCT) excited state is a very effective strategy for producing an organic light-emitting diode (OLED) with a high exciton utilization efficiency and external quantum efficiency. Herein, a novel twisting D–π–A fluorescent molecule (triphenylamine–anthracene–phenanthroimidazole; TPAAnPI) is designed and synthesized. The excited state properties of the TPAAnPI investigated through photophysical experiments and density functional theory (DFT) analysis reveal that its fluorescence is due to the HLCT excited state. The optimized non-doped blue OLED using TPAAnPI as a light-emitting layer exhibits a novel blue emission with an electroluminescence (EL) peak at 470 nm, corresponding to the Commission International de L''Eclairage (CIE) coordinates of (0.15, 0.22). A fabricated device termed Device II exhibits a maximum current efficiency of 18.09 cd A⁻¹, power efficiency of 12.35 lm W⁻¹, luminescence of ≈29 900 cd cm⁻², and external quantum efficiency (EQE) of 11.47%, corresponding to a high exciton utilization efficiency of 91%. Its EQE remains as high as 9.70% at a luminescence of 1000 cd m⁻² with a low efficiency roll-off of 15%. These results are among the best for HLCT blue-emitting materials involved in non-doped blue fluorescent OLEDs. The performance of Device II highlights a great industrial application potential for the TPAAnPI molecule.

A new pure fluorescent blue HLCT-emitter was designed and synthesized. Highly efficient non-doped blue OLEDs with low efficiency roll-off were achieved.     

OLED器件新型应用研究进展

有机发光二极管(organic light-emitting diodes,OLED)具有可柔性制备、低驱动电压、低功耗等优点,近年来技术上的突飞猛进及其广泛的应用前景,使之成为平板显示、新型照明、可穿戴,以及智能电子产品开发中最热门的研究课题之一.作为新一代的显示及照明技术,小尺寸OLED显示器已实现商业化,大尺寸O...     

从混合模空间到加权型空间上的加权复合算子的差分

In this paper,we study the boundedness and estimate the essential norm of the differences of weighted composition operators from mixed-norm spaces to weighted-type spaces on the unit ball of CN.     

次磷酸铝协同硼酸锌阻燃聚乙烯

以次磷酸铝(AHP)和硼酸锌(ZB)为复合阻燃剂,通过熔融共混法制备了阻燃聚乙烯(PE)材料,研究了AHP和ZB对PE的协同阻燃效应。 结果表明,AHP、ZB阻燃剂在PE基体中分散均匀;添加质量分数为25%AHP阻燃剂,PE材料的极限氧指数值(LOI)提升至25%,通过垂直燃烧测试(UL-94(3.2 mm))V-2级,显示出良好的阻燃效果;引入ZB后,材料LOI值呈先升高后下降趋势,在m(AHP):m(ZB)=21:4时,出现峰值,达到27.2%,并通过UL-94(3.2 mm)V-1级;热失重分析(TGA)结果显示,AHP、ZB阻燃剂能同时提高PE材料的热稳定性和成炭率,当m(AHP):m(ZB)=17:8时,残渣率达到25.7%。     

Thermal decomposition process of silver behenate

The thermal decomposition processes of silver behenate have been studied by infrared spectroscopy (IR), X-ray diffraction (XRD), combined thermogravimetry-differential thermal analysis-mass spectrometry (TG-DTA-MS), transmission electron microscopy (TEM) and UV-vis spectroscopy. The TG-DTA and the higher temperature IR and XRD measurements indicated that complicated structural changes took place while heating silver behenate, but there were two distinct thermal transitions. During the first transition at 138 °C, the alkyl chains of silver behenate were transformed from an ordered into a disordered state. During the second transition at about 231 °C, a structural change took place for silver behenate, which was the decomposition of silver behenate. The major products of the thermal decomposition of silver behenate were metallic silver and behenic acid. Upon heating up to 500 °C, the final product of the thermal decomposition was metallic silver. The combined TG-MS analysis showed that the gas products of the thermal decomposition of silver behenate were carbon dioxide, water, hydrogen, acetylene and some small molecule alkenes. TEM and UV-vis spectroscopy were used to investigate the process of the formation and growth of metallic silver nanoparticles.     

Simultaneous analyses of neutral carbohydrates and amino sugars in freshwaters with HPLC-PAD

In this study, we determine concentrations of neutral and amino sugars and a sugar alcohol in freshwaters using high-performance liquid chromatography and pulsed amperometric detection with a single isocratic analysis. Coeluting arabinose, galactosamine, and mannosamine are separated with a mobile phase of 22.8 mM NaOH-KOH at a temperature of 17 degrees C. The resolutions are 0.73 and 0.64, respectively. The method separates closely eluting glucose-mannose and mannose-xylose peaks with resolutions of 0.85 and 0.71. Other sugars, fucose, rhamnose, galactose, fructose, ribose, glucosamine, and mannitol are resolved completely. Arabinose and galactosamine are measured in stream, ground, and soil waters that contain dissolved total saccharide (DTS) concentrations of 527 to 1555 nM. Failure to distinguish galactosamine from arabinose in those samples results in a 53-82% overestimation of arabinose concentrations and a 1.8-6.5% overestimation of DTS concentrations. The near unity of glucosamine and galactosamine concentrations in stream water samples allows us to suggest a correction factor for historical samples that had been analyzed without resolving galactosamine and arabinose.     

溴化交联聚丙烯腈的合成及其结构性能的研究

以丙烯腈为反应性单体,二乙烯苯为交联剂,甲苯为致孔剂,用悬浮聚合方法制得了一系列不同交联度和不同致孔剂含量的丙烯腈交联聚合物。然后与溴化氢反应进行化学修饰,得到溴化聚丙烯清,讨论了不同交联度和不同致孔剂用量对溴化程度的影响。     

Anodic oxidation triggered divergent 1,2- and 1,4-group transfer reactions of β-hydroxycarboxylic acids enabled by electrochemical regulation

We report a set of electrochemically regulated protocols for the divergent synthesis of ketones and β-keto esters from the same β-hydroxycarboxylic acid starting materials. Enabled by electrochemical control, the anodic oxidation of carboxylic acids proceeded in either a one-electron or a two-electron pathway, leading to a 1,4-aryl transfer or a semipinacol-type 1,2-group transfer product with excellent chemoselectivity. The 1,4-aryl transfer represents an unprecedented example of carbon-to-oxygen group transfer proceeding via a radical mechanism. In contrast to previously reported radical group transfer reactions, this 1,4-group transfer process features the migration of electron-rich aryl substituents. Furthermore, with these chemoselective electrochemical oxidation protocols, a range of ketones and β-keto esters including those possessing a challenging-to-access medium-sized ring could be synthesized in excellent yields.

We report a set of electrochemically regulated protocols for the divergent synthesis of ketones and β-keto esters from the same β-hydroxycarboxylic acid starting materials.     

Optimization of Extraction Process and the Antioxidant Activity of Phenolics from Sanghuangporus baumii

Sanghuangporus baumii, is a widely used medicinal fungus. The polyphenols extracted from this fungus exert antioxidant, anti-inflammatory, and hypoglycemic effects. In this study, polyphenols from the fruiting bodies of S. baumii were obtained using the deep eutectic solvent (DES) extraction method. The factors affecting the extraction yield were investigated at different conditions. Based on the results from single-factor experiments, response surface methodology was used to optimize the extraction conditions. The scavenging ability of the polyphenols on •OH, DPPH, and ABTS⁺ was determined. The results showed that the DES system composed of choline chloride and malic acid had the best extraction yield (6.37 mg/g). The optimal extraction parameters for response surface methodology were as follows: 42 min, 58 ℃, 1:34 solid–liquid (mg/mL), and water content of 39%. Under these conditions, the yield of polyphenols was the highest (12.58 mg/g). At 0.30 mg/mL, the scavenging ability of the polyphenols on •OH, DPPH, and ABTS⁺ was 95.71%, 91.08%, and 85.52%, respectively. Thus, the method using DES was more effective than the conventional method of extracting phenolic compounds from the fruiting bodies of S. baumii. Moreover, the extracted polyphenols exhibited potent antioxidant activity.     

Design,Synthesis and Insecticidal Activities of Novel 5-Alkoxyfuran-2(5H)-one Derivatives

A series of novel 5?alkoxyfuran-2(5H)-one derivatives was synthesized, and characterized by 1H NMR, 13C NMR and HRMS. Biological activities of all the title compounds were evaluated systematically. Preliminary bioassays indicated that most of the compounds exhibited moderate insecticidal activities against Aphis craccivora and Nilaparvata lugens at 100 mg/L. Compounds 4h and 4w exhibited 100% mortality rate against Aphis craccivora at 100 mg/L, and compound 4h exhibited good mortality rate against Aphis craccivora and Nilaparvata lugens (60% and 75%, respectively) even at 4 mg/L. The results demonstrated the impact of various chemical groups on insecticidal activities and provided a potential clue for further exploring novel high-effective broad-spectrum insecticides.