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441.
Jibiao Jin Chunbo Duan He Jiang Peng Tao Hui Xu Wai-Yeung Wong 《Angewandte Chemie (International ed. in English)》2023,62(18):e202218947
Developing deep-blue thermally activated delayed fluorescence (TADF) emitters with both high efficiency and color purity remains a formidable challenge. Here, we proposed a design strategy by integrating asymmetric oxygen-boron-nitrogen (O−B−N) multi-resonance (MR) unit into traditional N−B−N MR molecules to form a rigid and extended O−B−N−B−N MR π-skeleton. Three deep-blue MR-TADF emitters of OBN , NBN and ODBN featuring asymmetric O−B−N, symmetric N−B−N and extended O−B−N−B−N MR units were synthesized through the regioselective one-shot electrophilic C−H borylation at different positions of the same precursor. The proof-of-concept emitter ODBN exhibited respectable deep-blue emission with Commission International de l′Eclairage coordinate of (0.16, 0.03), high photoluminescence quantum yield of 93 % and narrow full width at half maximum of 26 nm in toluene. Impressively, the simple trilayer OLED employing ODBN as emitter achieved a high external quantum efficiency up to 24.15 % accompanied by a deep blue emission with the corresponding CIE y coordinate below 0.1. 相似文献
442.
Tiantian Zhang Yuxin Xiao Hailan Wang Shuting Kong Rongjuan Huang Dr. Vonika Ka-Man Au Prof. Tao Yu Prof. Wei Huang 《Angewandte Chemie (International ed. in English)》2023,62(39):e202301896
Thermally activated delayed fluorescence (TADF) materials have attracted great potential in the field of organic light-emitting diodes (OLEDs). Among thousands of TADF materials, highly twisted TADF emitters have become a hotspot in recent years. Compared with traditional TADF materials, highly twisted TADF emitters tend to show multi-channel charge-transfer characters and form rigid molecular structures. This is advantageous for TADF materials, as non-radiative decay processes can be suppressed to facilitate efficient exciton utilization. Accordingly, OLEDs with excellent device performances have also been reported. In this Review, we have summarized recent progress in highly twisted TADF materials and related devices, and give an overview of the molecular design strategies, photophysical studies, and the performances of OLED devices. In addition, the challenges and perspectives of highly twisted TADF molecules and the related OLEDs are also discussed. 相似文献
443.
Yanyun He Prof. Weixu Feng Yujie Qiao Zhixuan Tian Prof. Ben Zhong Tang Prof. Hongxia Yan 《Angewandte Chemie (International ed. in English)》2023,62(48):e202312571
Non-traditional fluorescent polymers have attracted significant attention for their excellent biocompatibility and diverse applications. However, designing and preparing non-traditional fluorescent polymers that simultaneously possess long emission wavelengths and long fluorescence lifetime remains challenging. In this study, a series of novel hyperbranched polyborosiloxanes (P1–P4) were synthesized. As the electron density increases on the monomer diol, the optimal emission wavelengths of the P1–P4 polymers gradually red-shift to 510, 570, 575, and 640 nm, respectively. In particular, P4 not only exhibits red emission but also demonstrates delayed fluorescence with a lifetime of 9.73 μs and the lowest critical cluster concentration (1.76 mg/mL). The experimental results and theoretical calculations revealed that the synergistic effect of dual heteroatom-induced electron delocalization and through-space O⋅⋅⋅O and O⋅⋅⋅N interaction was the key factor contributing to the red-light emission with delayed fluorescence. Additionally, these polymers showed excellent potential in dual-information encryption. This study provides a universal design strategy for the development of unconventional fluorescent polymers with both delayed fluorescence and long-wavelength emission. 相似文献
444.
Subeesh Madayanad Suresh Le Zhang David Hall Changfeng Si Gaetano Ricci Tomas Matulaitis Alexandra M. Z. Slawin Stuart Warriner Yoann Olivier Ifor D. W. Samuel Eli Zysman-Colman 《Angewandte Chemie (International ed. in English)》2023,62(8):e202215522
We present a p- and n-doped nonacene compound, NOBNacene, that represents a rare example of a linearly extended ladder-type multiresonant thermally activated delayed fluorescence (MR-TADF) emitter. This compound shows efficient narrow deep blue emission, with a λPL of 410 nm, full width at half maximum, FWHM, of 38 nm, photoluminescence quantum yield, ΦPL of 71 %, and a delayed lifetime, τd of 1.18 ms in 1.5 wt % TSPO1 thin film. The organic light-emitting diode (OLED) using this compound as the emitter shows a comparable electroluminescence spectrum peaked at 409 nm (FWHM=37 nm) and a maximum external quantum efficiency (EQEmax) of 8.5 % at Commission Internationale de l’Éclairage (CIE) coordinates of (0.173, 0.055). The EQEmax values were increased to 11.2 % at 3 wt % doping of the emitter within the emissive layer of the device. At this concentration, the electroluminescence spectrum broadened slightly, leading to CIE coordinates of (0.176, 0.068). 相似文献
445.
Jonas Schmidt Dr. Luis I. Domenianni Marcel Leuschner Prof. Dr. Andreas Gansäuer Prof. Dr. Peter Vöhringer 《Angewandte Chemie (International ed. in English)》2023,62(35):e202307178
Titanium-based catalysis in single electron transfer (SET) steps has evolved into a versatile approach for the synthesis of fine chemicals and first attempts have recently been made to enhance its sustainability by merging it with photo-redox (PR) catalysis. Here, we explore the photochemical principles of all-Ti-based SET-PR-catalysis, i.e. in the absence of a precious metal PR-co-catalyst. By combining time-resolved emission with ultraviolet-pump/mid-infrared-probe (UV/MIR) spectroscopy on femtosecond-to-microsecond time scales we quantify the dynamics of the critical events of entry into the catalytic cycle; namely, the singlet-triplet interconversion of the do-it-all titanocene(IV) PR-catalyst and its one-electron reduction by a sacrificial amine electron donor. The results highlight the importance of the PR-catalyst's singlet-triplet gap as a design guide for future improvements. 相似文献
446.
Yihang Jiao Zijian Chen Dr. Weidong Qiu Hongwei Xie Jiaji Yang Dr. Xiaomei Peng Dr. Wentao Xie Qing Gu Dr. Mengke Li Dr. Kunkun Liu Prof. Shi-Jian Su 《Angewandte Chemie (International ed. in English)》2023,62(38):e202309104
Polychlorinated (hetero)arenes have shown great promise for organic optoelectronics applications. However, the harsh synthetic routes for polychlorinated compounds and the possible luminescence quenching from the compact intermolecular π–π stacking induced by chlorine atoms limit their investigations and applications in luminescent materials. Herein, two isomeric polychlorinated polycyclic aromatic hydrocarbon (PAH) compounds JY-1-Cl and JY-2-Cl consisting of rigidified aryl ketones and amine are designed and synthesized under mild conditions through nucleophilic chlorination intermediated by an electron donor-acceptor complex. Among them, as a result of the strong π–π interactions induced by chlorine atoms, JY-2-Cl exhibits bright monomer and dimer emissions with dual thermally activated delayed fluorescence (TADF) characters. Notably, compared with the non-chlorinated compounds, a high photoluminescence quantum yield is maintained after introducing multiple chlorine atoms into JY-2-Cl . The first dual-TADF organic light-emitting diodes are also successfully fabricated with maximum external quantum efficiency as high as 29.1 % by employing JY-2-Cl as emitter. This work presents a new paradigm and synthesis of polychlorinated amine-carbonyl PAHs and demonstrates the great potential of the chlorinated materials for luminescent applications. 相似文献
447.
Françoise Ehrburger-Dolle Françoise Bley Erik Geissler Frédéric Livet Isabelle Morfin Cyrille Rochas 《Macromolecular Symposia》2003,200(1):157-168
Elastomers are soft materials that can be reinforced by dispersing into them nanosized solid particles. Common examples of the latter are silica or carbon black aggregates. However, the mechanism of reinforcement is still not yet fully understood. Our work consists in investigating by small-angle X-ray scattering (SAXS) the structure of the aggregate network spreading throughout the matrix in the initial sample and its modification during and after straining (elongation). The goal is to relate the macroscopic mechanical behaviour with the structure of the aggregate network. The present paper is a qualitative overview of recent results obtained on well defined composites. 相似文献
448.
Hai-Jie Wang Prof. Dr. Yuan Liu Baoqiu Yu Shi-Quan Song Prof. Dr. You-Xuan Zheng Dr. Kanglei Liu Prof. Dr. Pangkuan Chen Prof. Dr. Hailong Wang Prof. Dr. Jianzhuang Jiang Prof. Dr. Tian-Yi Li 《Angewandte Chemie (International ed. in English)》2023,62(7):e202217195
Thermally activated delayed fluorescence (TADF) from linear two-coordinate coinage metal complexes is sensitive to the geometric arrangement of the ligands. Herein we realize the tuning of configuration from coplanar to orthogonal gradually by variation of substituents. In a complex with confined twist configuration, its blue emission peaking at 458 nm presents a high ΦPL of 0.74 and a short τTADF of 1.9 μs, which indicates a fast enough kr,TADF of 3.9×105 s−1 and a depressed knr of 1.4×105 s−1. Such outstanding luminescent properties are attributed to the proper overlap of HOMO and LUMO on CuI d orbitals that guarantees not only small ΔEST but also sufficient transition oscillator strength for fast . Vacuum-deposited blue OLEDs with either doped or host-free emissive layer present external quantum efficiencies over 20 % and 10 %, respectively, demonstrating the practicality of the configurationally confined strategy for efficient linear CuI TADF emitters. 相似文献