Multiresonance thermally activated delayed fluorescence (MR‐TADF) emitters manifest great potential for organic light‐emitting diodes (OLEDs) due to their high exciton‐utilization efficiency and ...narrowband emission. Nonetheless, their tendency toward self‐quenching caused by strong interchromophore interactions would induce doping sensitivity and deteriorate the device performances, and effective strategy to construct quenching‐resistant emitters without sacrifycing color purity is still to be developed. By segregating the planar MR‐TADF skeleton using two bulky carbazolyl units, herein a highly emissive molecule with enhanced quenching resistance is reported. The steric effect largely removes the formation of detrimental excimers/aggregates, and boosts the performance of the corresponding devices with a maximum external quantum efficiency (EQEmax) up to 40.0% and full width at half maximum (FWHM) of 25 nm, representative of the only example of single OLED that can concurrently achieve narrow bandwidth and high EL efficiency surpassing 40% to date. Even at doping ratio of 30 wt%, the EQEmax is retained to be 33.3% with nearly unchanged emission spectrum. This work provides a viable approach to realize doping‐insensitive MR‐TADF devices with extreme EL efficiency and color purity for high‐end OLED displays.
A molecular design tactic to achieve quenching‐resistant multiresonance thermally activated delayed fluorescence (MR‐TADF) emitters is proposed by fencing the MR‐skeleton with steric units. Excellent electroluminescence performances are recorded in corresponding organic light‐emitting diodes, with record‐breaking external quantum efficiencies up to 40.0% and full width at half maximum values of only 25 nm.
Display omitted
•Narrowband green emitters are successfully achieved by multi-resonance boron-nitrogen framework.•Heavy-atom effect of sulfur was beneficial to accelerate the reverse intersystem ...crossing.•Green organic light-emitting diodes with high external quantum efficiency up to 25.5% are achieved.
As one type of latest emitters with simultaneous high efficiency and color-purity, the development of multi-resonance thermally activated delayed fluorescence (MR-TADF) materials represents an important advancement for organic light-emitting diodes (OLEDs). We herein present a new strategy to improve the performance of MR-TADF emitters by fusing sulfur element into the B-N based framework, aiming to utilize the non-metal heavy-atom effect in accelerating the reverse intersystem crossing (RISC) process of the emitter. Two compounds, namely 2PTZBN and 2PXZBN, were developed in this work through rigidifying the DABNA-1 skeleton by sulfur or oxygen atoms. The theoretical calculations and photoluminescence studies reveal that the sulfur-incorporated 2PTZBN enable considerable rate constant of RISC (kRISC) up to 2.8 × 105 s−1 in toluene due to larger spin-orbital coupling (SOC) values and smaller singlet–triplet energy splitting (ΔEST) compared with 2PXZBN. Consequently, organic light-emitting diodes based on 2PTZBN exhibited highly efficient green emission with maximum external quantum efficiency (EQE) of 25.5%.
During the last few years, organoboron‐based thermally activated delayed fluorescence (TADF) materials have received extensive attention in optoelectronic area, owing to the unique electronegativity ...of boron atom. Herein, many research progress of organoboron‐based TADF materials for organic optoelectronic devices is summarized. This review comprehensively documents the organoboron‐based TADF materials according to the emission colors from blue to red‐near‐infrared (red‐NIR), covering the molecular design strategies, photophysical properties, and optoelectronic performance in organic light‐emitting diodes (OLEDs). The current progress and future challenges in this fast‐growing fields are reviewed systematically, providing instructive guidance for the future research on high‐performance TADF‐OLEDs.
Recent progress on versatile boron‐based thermally activated delayed fluorescence materials for organic light‐emitting diodes is systematically summarized according to the emission colors, covering the molecular design strategies, photophysical properties, and optoelectronic performance in the organic light‐emitting diodes. The current challenges and future directions in this rapidly growing field are commented.
Multi‐resonance thermally activated delayed fluorescence (MR‐TADF) offers an exceptional solution for narrowband organic light‐emitting diode devices in terms of color purity and luminescence ...efficiency, while the development of new MR skeleton remains an exigent task. It is hereby demonstrated that a simple modification of the B (boron)−N (nitrogen) framework by sp3‐carbon insertion will significantly bathochromic shift the short‐range charge‐transfer emission, boost the reverse intersystem crossing process, and improve the device performances. The bis(acridan)phenylene‐based skeleton developed in this contribution presents a non‐planar conformation with functional sites to facilely introduce isolating units, deriving two luminophores with quantum yields approaching 90% in film state and narrowband emission. Corresponding green‐emissive devices realize superior performances compared to the planar carbazolyl‐based MR‐TADF analogs, featuring a maximum external quantum efficiency (EQEmax) up to 28.2% and small efficiency roll‐off without the involvement of any sensitizing host.
A simple modification of the B (boron)−N (nitrogen) framework by sp3‐carbon insertion will significantly bathochromic shift the emission, boost the reverse intersystem crossing process, and lead to highly‐efficient green electroluminescence with low roll‐off.
Display omitted
•Emitter shows on–off switchable crystal-dependent TADF, AIE and multicolor MCL.•On-off TADF behavior can be controlled via a variety of simple external stimuli.•The underlying ...mechanisms of the tunable luminescent features are explored deeply.
To develop multifunctional emitters, a pair of structural isomers, TRZ-c-BPXZ and TRZ-a-BPXZ, with 7H-benzocphenoxazine (c-BPXZ) and 12H-benzoaphenoxazine (a-BPXZ) as donors, and triphenyltriazine as acceptor, are designed and synthesized. Impressively, TRZ-c-BPXZ not only exhibits on–off switchable crystal-dependent thermally activated delayed fluorescence (TADF) characteristic, but the on–off TADF emission in different aggregation states can be reversibly manipulated via a lot of channels, such as grinding, heating, fuming, recrystallizing, vacuum evaporation and sublimation. Through the detailed theoretical simulation, as well as thoroughly analysis of packing arrangements and molecular conformations of single crystals, it reveals that not only is the planar donor crucial to designing TADF molecules, but also the quasi-equatorial configuration of molecules is significant. And the appropriate π···π stacking in dimers also lengthens the delayed lifetime. Overall, these results shed light on the underlying mechanism of the tunable photophysical properties and on–off switchable TADF behavior. To the best of our knowledge, TRZ-c-BPXZ is the first example of achieving molecular on–off controllable TADF characteristic by a variety of convenient methods.
At present, clinical nutritional care for patients with pancreatic cancer focuses more on the observation of the effect of enteral parenteral nutrition, and there is a lack of personalised care plans ...for weight-loss control. We used the Delphi method to construct a set of personalised nursing programmes to effectively control the rate of postoperative weight loss in patients with pancreatic cancer.
This study was a cross-sectional investigation. Through literature analysis, literature review and data review, a personalised nursing plan for the postoperative weight-loss control in patients with pancreatic cancer was preliminarily developed. From October to December 2022, the Delphi method was adopted to conduct two questionnaires for 32 experts working in fields related to pancreatic diseases in Grade-A tertiary hospitals from four different departments. After statistical processing, the personalised nursing plan was determined according to the perceived level of importance, coefficient of variation, full score rate and recognition rate of the indicators.
The recovery rates of the two rounds of consultation were 93.75% and 100%, respectively, and the overall authority coefficient of the experts was 0.918, which represented 'authoritative'. In terms of importance, the coefficient of variation was 0-0.137; in terms of feasibility, the coefficient of variation ranged from 0.09 to 0.194. Finally, a scheme consisting of 36 entries in 8 dimensions was built. This programme is comprehensive in content, meets the nutritional diagnosis and treatment needs of patients in the stage of postoperative rehabilitation, provides relatively comprehensive nutritional assessment and support and has a robust system and feasibility.
The individualised nursing plan for patients with pancreatic cancer with postoperative weight-loss control based on the Delphi method is highly scientific and reliable and has positive significance.
A novel approach to synthesize symmetric 1,7-dicarbonyl compounds viaa tandem radical addition-elimination-addition reaction of S-carbonylmethyl xanthates with allylmethylsulfone and its analogues ...has been developed. Radicals were produced from S-carbonylmethyl xanthates by adding dilauroyl peroxide and reacted with allylmethylsulfone or analogues to generate terminal olefins as intermediates. The excessive radicals reacted with the intermediate olefins immediately to give adducts of symmetric 1,7-dicarbonyl compounds. This is an efficient method to synthesize 1,7-dicarbonyl compounds under mild conditions.
Ubiquitination-mediated M1/M2 macrophage polarization plays important roles in the pathogenesis of immune disease. However, the regulatory mechanism of ubiquitination during M1/M2 macrophage ...polarization following intracerebral hemorrhage (ICH) has not been well studied.
In the experiment, macrophages were administered with erythrocyte lysates, and then miR-494-, Nrdp1-, and M1/M2-related markers were analyzed. Brain inflammatory response, brain edema, and neurological functions of ICH mice were also assessed.
We found that miR-494 levels increased while Nrdp1 levels decreased in macrophages after ICH. We also demonstrated that miR-494 inhibited Nrdp1 expression by directly binding its 3'-untranslated region. MiR-494 attenuated C/EBP-β activation and downstream proinflammatory factor production. Upregulation of Nrdp1 in macrophages significantly promoted M2 macrophage polarization via ubiquitinating and activating C/EBP-β. Moreover, the results indicated that miR-494 could enhance M1 macrophage polarization, promote brain edema, and impair neurological functions in ICH mice.
Taken together, our results demonstrated that Nrdp1 contributed to M1/M2 macrophage polarization and neuroinflammation via ubiquitination and activation of C/EBP-β in ICH. miR-494 may provide a promising therapeutic clue for ICH.
Neuregulin receptor degradation protein-1 (Nrdp1) is an E3 ubiquitin ligase that plays an important role in regulating cell growth, apoptosis and oxidative stress. However, the data regarding its ...expression and exact mechanism in neuronal injury following ICH has not been well identified.
In this study, primary cortical neurons from C57BL/6 mice were subjected to erythrocyte lysates. Nrdp1 expression, cell apoptosis, caspase-3 and BRUCE levels were detected. In addition, inflammatory response, brain edema, and neurological injury in ICH mice were also assessed.
We found that the expression of Nrdp1 was significantly increased in neuron cells accompanied by up-regulation of active caspase-3 and decreased expression of BRUCE (an inhibitor of apoptosis protein). However, inhibiting Nrdp1 levels of neurons reduced caspase-3 activity but induced up-regulation of BRUCE. In vivo, inhibiting Nrdp1 levels increased pro-inflammatory cytokines, brain edema, and neurological injury following ICH.
Taken together, the data suggested that Nrdp1 might play a crucial role in neuronal apoptosis via inhibiting BRUCE following ICH.
Factor analysis was used to investigate the changes of dry-wet climate in the dry season in Yunnan during 1961–2007 based on observed data from 15 stations. Three common factors were extracted from ...the 9 climatic factors. The results showed that the dry-wet climate has evidently changed since the early 1960s. The general trends in the changes of dry-wet climate were described as slight decrease in humidity and gradual enhancement in drought intensity. The climate during 1960s–1980s was under weak-medium drought. But since early 1990s, dry conditions have markedly strengthened and continued due to uneven temporal distribution of rainfall and climate warming.
Huang, Z., 2011: Changes of dry-wet climate in the dry season in Yunnan (1961–2007). Adv. Clim. Change Res.,2(1), doi: 10.3724/SP.J.1248.2011.00049.
PDF
