High-Performance Solution-Processed Nondoped Circularly Polarized OLEDs with Chiral Triptycene Scaffold-Based TADF Emitters Realizing Over 20% External Quantum Efficiency

Recently, circularly polarized organic light-emitting diodes (CP-OLEDs) fabricated with thermally activated delayed fluorescence (TADF) emitters are developed rapidly. However, most devices are fabricated by vacuum deposition technology, and developing efficient solution-processed CP-OLEDs, especially nondoped devices, is still a challenge. Herein, a pair of triptycene-based enantiomers, (S,S)-/(R,R)-TpAc-TRZ, are synthesized. The novel chiral triptycene scaffold of enantiomers avoids their intermolecular π–π stacking, which is conducive to their aggregation-induced emission characteristics and high photoluminescence quantum yield of 85% in the solid state. Moreover, the triptycene-based enantiomers exhibit efficient TADF activities with a small singlet-triplet energy gap (ΔE_ST) of 0.03 eV and delayed fluorescence lifetime of 1.1 µs, as well as intense circularly polarized luminescence with dissymmetry factors (|g_PL|) of about 1.9 × 10⁻³. The solution-processed nondoped CP-OLEDs based on (S,S)-/(R,R)-TpAc-TRZ not only display obvious circularly polarized electroluminescence signals with g_EL values of +1.5 × 10⁻³ and −2.0 × 10⁻³, respectively, but also achieve high efficiencies with external quantum, current, and power efficiency up to 25.5%, 88.6 cd A⁻¹, and 95.9 lm W⁻¹, respectively.     

Relationships of tensile strength with crosslink density for the high-carbon black-filled EPDM compounds with various softeners

Equilibrium swelling and rheological tests were adopted to systematically investigate the effects of softener type and dosage on the crosslink densities. The results turned out that the chemical crosslink density could be distinguished from the physical crosslink density by comparing the results of equilibrium swelling and rheological tests. The liquid butadiene (LB) as a softener leads to the greatest reduction in crosslink density, followed by polyethylene wax (PW) and paraffinic oil (PO). The tensile strength decreases with increasing PO content while shows peak values with increase of LB and PW contents. The dependencies of chemical crosslink density on the aging time under 150°C are quite different for the three softeners, which can be expected from the double crosslinking networks consisting of small softener and large main crosslinking networks. Further investigation has been performed to correlate the tensile strength with chemical crosslink density of ethylene propylene diene monomer elastomer vulcanizates. Three different linear relationships can be obtained for the softeners independent of the aging time. It can now be expected from this study that the role of some new softeners in rubber compounds is not only confined to plasticization but also forms crosslinking networks in the peroxide-cured rubbers.     

Examining the Impact of Squaric Acid as a Crosslinking Agent on the Properties of Chitosan-Based Films

Hydrogels based on chitosan are very versatile materials which can be used for tissue engineering as well as in controlled drug delivery systems. One of the methods for obtaining a chitosan-based hydrogel is crosslinking by applying different components. The objective of the present study was to obtain a series of new crosslinked chitosan-based films by means of solvent casting method. Squaric acid—3,4-dihydroxy-3-cyclobutene-1,2-dione—was used as a safe crosslinking agent. The effect of the squaric acid on the structural, mechanical, thermal, and swelling properties of the formed films was determined. It was established that the addition of the squaric acid significantly improved Young’s modulus, tensile strength, and thermal stability of the obtained materials. Moreover, it should be stressed that the samples consisting of chitosan and squaric acid were characterized by a higher swelling than pure chitosan. The detailed characterization proved that squaric acid could be used as a new effective crosslinking agent.     

Achieving High Electroluminescence Efficiency and High Color Rendering Index for All-Fluorescent White OLEDs Based on an Out-of-Phase Sensitizing System

Sensitizing conventional fluorescence (CF) dopants with thermally activated delayed fluorescence (TADF) materials has achieved considerable progress, by which the advantages of TADF materials and CF dopants can be fully harnessed. However, the usually used co-phase configuration of CF dopant-engaged sensitizing systems often encounters exciton loss due to Dexter energy transfer (DET). Herein, an effective out-of-phase configuration is proposed to sensitize CF dopants in the fabrication of white organic light-emitting diodes (WOLEDs). Based on a new efficient sky-blue TADF luminogen DCP-BP-DPAC which has an electroluminescence (EL) peak at 486 nm and an EL efficiency of 26.6%, a green TADF material BDMAC-XT, and a red CF dopant DBP sensitized by BDMAC-XT through an out-of-phase configuration without interlayer, efficient WOLEDs are successfully fabricated. By further adopting orange TBRB or 4CzTPNBu as intermediate sensitizers, more efficient energy transfer to DBP is achieved via Förster energy transfer. Through step-by-step energy transfer and elimination of excess DET process, high-performance all-fluorescent WOLEDs are achieved, providing excellent EL efficiencies over 23.0%, and highly stable white light with a high color rendering index of 87. The outstanding EL performance and high-quality emission color demonstrate the great potential of the proposed out-of-phase design for sensitizing systems of WOLEDs.     

Highly efficient full-fluorescence organic light-emitting diodes with exciplex cohosts

Full-fluorescence organic light-emitting diodes (FOLEDs) with low cost and high efficiency are imperious demands for commercial process in flat panel display and lighting products. We fabricated a series of FOLEDs employing C545T and DCJTB as doped dyes and different exciplex blends as cohosts. The results proved that reverse intersystem crossing (RISC) efficiency of exciplex cohost has a significant effect on the device performance. Devices with TAPC:PIM-TRZ as cohost which possessed the highest RISC efficiency showed the best results. The green FOLEDs exhibited the maximum external quantum efficiencies (EQEs) approaching to 20%, the red FOLEDs exhibited EQEs over 10% and all the EQE roll-offs are less than 10% at 1000 cd m⁻², which are among the best reported results so far, suggesting these exciplex cohosts are promising for FOLEDs.     

基于衰变链计算的裂变产物缓发γ能谱分析

在军控核查技术中，缓发γ能谱是核材料的“指纹”。为计算和分析铀裂变产物的缓发γ能谱，本文将各种类型的衰变链简化为基态线性链和激发态线性链，推导了零时前后各级核素数目的变化公式，建构了计算缓发γ射线能谱的C语言程序代码，并通过实验对理论推导进行了验证。通过分析几种核素的缓发γ射线计数发现，计算结果与实验数据吻合较好。     

亚麻蛋白冰淇淋品质影响因素及评价

以冷榨法榨油后的亚麻籽饼粕为原料，亚麻籽饼粕采用酶制剂提取脱胶、脱脂获得亚麻蛋白，研究亚麻蛋白在冰淇淋配方中的应用。影响亚麻蛋白冰淇淋的因素为：亚麻蛋白、奶油、脱脂奶粉和蔗糖，以感官评价为指标，采用单因素实验和正交实验优化亚麻蛋白冰淇淋配方。确定最佳配方为：亚麻蛋白含量3%、脱脂奶粉含量13%、奶油含量15%、蔗糖含量16%。应用此配方亚麻蛋白冰淇淋感官评分为95.32±0.41分，膨胀率为69.67%±0.91%，抗融性5.28%±0.98%。     

基于热负荷自动调节的延迟焦化加热炉三点注汽量智能优化

针对国内某炼油厂延迟焦化加热炉三点注汽问题，采用热负荷自动调节的算法进行了研究。运用该模型方法，分析了三点注汽量对加热炉热负荷和炉管结焦系数的影响，发现三点注汽量的改变均会对热负荷和炉管结焦系数产生影响，主要表现为提高注汽量将会提高热负荷，同时降低结焦系数；第1点注汽量和第2点注汽量对热负荷和结焦系数的影响较强，第3点注汽量对热负荷和结焦系数的影响较弱。在实际操作中，加热炉中的结焦程度既不能太强也不能太弱，合适的结焦系数能够保证正常开工周期里炉管不结焦，也能保证瓦斯、注汽量等参数的合理分配。通过对热负荷、注汽量的智能分配，可得到不同原料油加工负荷条件下更加合理的装置运行方案。     

One‐shot radical polymerization of vinyl monomers with different reactivity accompanying spontaneous delay of polymerization for the synthesis of double‐network hydrogels

Double‐network hydrogels were conveniently synthesized by the one‐shot radical polymerization of an ionic monomer for the first network and a non‐ionic monomer for the second network in the presence of crosslinkers by simultaneous addition of the monomers, that is, one‐shot and spontaneous two‐step polymerization accompanying the delay of polymerization of a second network monomer. We analyzed the polymerization process based on the conversion of each monomer during the reaction in the absence of crosslinkers. Then we fabricated the double‐network hydrogels using several polymerization systems consisting of a conjugated monomer and a non‐conjugated monomer in the presence of the dual crosslinkers. We analyzed the swelling, mechanical and viscoelastic properties of hydrogels synthesized by one‐shot radical polymerization to confirm the production mechanism and the network structure of the hydrogels. © 2020 Society of Chemical Industry