Novel Spectrally Stable Saturated Blue‐Light‐Emitting Poly[(fluorene)‐co‐(dioctyldibenzothiophene‐S,S‐dioxide)]s

Novel poly[(fluorene)‐co‐(2,8‐dioctyldibenzothiophene‐S,S‐dioxide‐3,7‐diyl)]s were synthesized. The octyl group on the 2,8‐dioctyldibenzothiophene‐S,S‐dioxide (DOSO) unit improved the solubility of the polymers and broadened the optical band gap from 2.95 to 3.20 eV as the content of DOSO unit increases. The electroluminescence (EL) spectra of polymers show CIE coordinates around (0.16, 0.07) independent of the ratio of DOSO units in the polymers, owing to the ICT and steric hindrance dual‐function. A high efficiency of 3.1 cd · A⁻¹ (EQE = 3.9%) was obtained with the configuration of ITO/PEDOT:PSS/polymer/Ba/Al. The results indicate that PF‐3,7DOSOs could be a promising candidate for saturated blue‐emitting polymers with spectral stability and high efficiency.

     

First-principle band structure calculations of tris(8-hydroxyquinolinato)aluminum

Tris(8-hydroxyquinolinato)aluminum (Alq(3)) has been widely used in organic light-emitting diodes (OLEDs) both as electron transport and light-emitting materials. To gain a deeper understanding for its carrier transport properties, we carry out first-principle band-structure calculations using density-functional theory with generalized gradient approximation by the Becke exchange plus Lee-Yang-Parr correlation functional. The intermolecular interaction related to transport behavior has been analyzed from the Gamma-point wave function as well as from the bandwidths and band gaps. From the calculated bandwidths of the frontier bands as well as the effective masses of the electron and the hole, we conclude that the mobility of electron is about 2-3 times larger than that for the hole. Furthermore, when several bands near Fermi surface are taken into account, we find that the interband gaps within the unoccupied bands are generally smaller than those for the occupied bands, which indicate that the electron can hop from one band to another, much easier than the hole, through electron-phonon coupling for instance, thus, effectively representing an even larger mobility for the electron than for the hole. Therefore, from both the intra-band and inter-band processes point of view, the theory shows that that Alq(3) is a good electron transport material.     

Cross‐Linked Alq3‐Containing Polymers with Improved Electroluminescence Efficiency Used for OLEDs

Summary: Homopolymers and a series of copolymers with tris‐8‐hydroxyquinoline aluminum (Alq₃) as the cross‐links are synthesized. All these polymers show improved electroluminescence (EL) efficiency over their previously reported counterparts. Among them, the copolymers containing Alq₃ and carbazole groups show higher EL efficiency than that of the homopolymers. We also demonstrate the feasibility of generating patterns using the homopolymers via photopolymerization. The cross‐linked nature, selectivity of patterning, high thermal stability, and EL efficiency might render these polymers a promising material in fabricating large‐scaled multilayered sub‐pixellation organic light‐emitting diodes (OLEDs).

Current–voltage and the electroluminescence–voltage curve of two‐layer devices for the Alq₃‐homopolymers and the Alq₃‐copolymers (luminance is shown by the symbols without lines).     

Molecular engineering of an electron-transport triarylphosphine oxide-triazine conjugate toward high-performance phosphorescent organic light-emitting diodes with remarkable stability

Organic electron-transport materials are an essential component to boost performances and stability of organic light-emitting diodes. We present a robust organic electron-transport compound 3-(6-(3-(4,6-bis(4-biphenylyl)-1,3,5-triazin-2-yl)phenyl)pyridin-2-yl)phenyldiphenylphosphine oxide by facilely coupling the triphenylphosphine oxide moiety to the 2-phenyl-4,6-bis(4-biphenylyl)-1,3,5-triazine unit via a 2,6-pyridinylene linker. It is well soluble in weakly polar solvents and possesses a high T_g of 123 ℃ with an exceptional T_d≈470 ℃ at 1% weight loss and deep HOMO/LUMO levels of ca.-6.45/-3.06 eV. The phosphorescent spectrum measured in solid state at 77 K reveals a notable triplet energy of 2.88 eV. n-Doping with 8-hydroxyquinolatolithium(Liq) produces the electron mobility value of 4.66×10~(-5)–3.21×10~(-4) cm~2 V~(-1) s~(-1)@(2–5)×10~5 V cm~(-1).Moreover, the contrasting solubility of the bromo reaction intermediate and the new compound in alcoholic solvents facilitates separation. The characterizations of bottom-and top-emission green phosphorescent OLEDs involving this single Liq-doped electron-transport layer reveal long stability. In particular, the latter provides outstanding performances with 77.4 cd A~(–1)(corresponding to an EQE of 18.7%) and 86.8 lm W~(–1)@ca. 1000 cd m~(-2), based on the green emitter bis(2-phenylpyridine)(2-(4-methyl-3-phenylphenyl)pyridine)iridium(Ⅲ). Moreover, driven by a constant current for ca. 640 h, the initial luminance of 1000 cd m~(–2) appears almost no decay.     

Dual cocatalysts decorated three dimensionally ordered mesoporous g-C3N4 with homogeneous wall thickness for enhanced photocatalytic performance

Making several components be more intimate interfacial contacts in the photocatalyst is an efficient strategy to improve the separation and transfer of photogenerated charge carries and enhance the photocatalytic performance in the visible light region. In this work, a promising photocatalyst was fabricated by loading of Au nanoparticles and Cd_(0.58)Zn_(0.42)S nanoparticles onto the three dimensionally ordered mesoporous g-C₃N₄ material (Au/3DOM CN/Cd_(0.58)Zn_(0.42)S) via two-step synthesis method to significantly intensify the transfer capability of charge. The results of characterization demonstrate that Au/3DOM CN/Cd_(0.58)Zn_(0.42)S photocatalyst possesses the intimate interfacial contacts of three components and homogeneous wall thickness of 3DOM g-C₃N₄ framework, and these properties give Au/3DOM CN/Cd_(0.58)Zn_(0.42)S photocatalyst an ability that it can harvest a wider range of visible light and endow it superior photocatalytic activities for hydrogen evolution from water splitting and RhB degradation. Finally, a possible mechanism was proposed based on the photoelectrochemical measurement. This work would provide a new strategy to design and fabricate g-C₃N₄-based with 3DOM architecture materials with superior photocatalytic activity.     

First palladium‐catalyzed denitrated coupling reaction of nitroarenes with phenols

The first palladium‐catalyzed protocol for the denitrated coupling reaction of nitroarenes with phenols has been developed, achieving unsymmetrical diaryl ethers in moderate to excellent yields. The cyclopalladated ferrocenylimine (catalyst Ic ) exhibited highly catalytic activity for this transformation with low catalyst loading (0.75 mol%) and short reaction time (2 h). The efficiency of this reaction was demonstrated by its compatibility with a range of groups. Moreover, the rigorous exclusion of air or moisture was not required in these transformations. Copyright © 2013 John Wiley & Sons, Ltd.     

Design of a new pseudospark-produced high-brightness electron beam source

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High‐mobility flexible thin‐film transistors with a low‐temperature zirconium‐doped indium oxide channel layer

Thin film transistors (TFTs) with zirconium‐doped indium oxide (ZrInO) channel layer were successfully fabricated on a flexible PEN substrate with process temperature of only 150 °C. The flexible ZrInO TFT exhibited excellent electrical performance with a saturation mobility of as high as 22.6 cm² V^–1 s^–1, a sub‐threshold swing of 0.39 V/decade and an on/off current ratio of 2.5 × 10⁷. The threshold voltage shifts were 1.89 V and ?1.56 V for the unpassivated flexible ZrInO TFT under positive and negative gate bias stress, respectively. In addition, the flexible ZrInO TFT was able to maintain the relatively stable performance at bending curvatures larger than 20 mm, but the off current increased apparently after bent at 10 mm. Detailed studies showed that Zr had an effect of suppress the free carrier generation without seriously distorting the In₂O₃ lattice. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

5-卤代-2’-脱氧-2’-β-氟-4’-叠氮嘧啶核苷的合成与抗乙肝病毒活性研究

以(间氯)苯甲酰基保护的2’-脱氧-2’-β-氟-4’-叠氮尿苷为起始原料,经过硝酸铈铵(CAN)介导的卤代、三氮唑活化、胺化、脱保护合成了一系列5-卤代的2’-脱氧-2’-β-氟-4’-叠氮嘧啶核苷类化合物.体外生物活性评价研究表明, 5-氯代(6a)和5-碘代(6c)核苷衍生物具有很好的抗乙肝病毒活性,而且细胞毒性较小.