Developing red thermally activated delayed fluorescence (TADF) emitters,a ttainable for both high-efficient red organic light-emitting diodes (OLEDs) and non-doped deep red/near-infrared (NIR) OLEDs,ischallenging. Now,two red emitters,B PPZ-PXZ and mDPBPZ-PXZ, with twisted donor-acceptor structures were designed and synthesized to study molecular design strategies of high-efficiency red TADF emitters.B PPZ-PXZ employs the strictest molecular restrictions to suppress energy loss and realizes red emission with aphotoluminescence quantum yield (F PL )of100 AE 0.8 %and external quantum efficiency (EQE) of 25.2 %i nadoped OLED.Its non-doped OLED has an EQE of 2.5 %owingto unavoidable intermolecular p-p interactions.mDPBPZ-PXZ releases two pyridine substituents from its fused acceptor moiety.A lthough mDPBPZ-PXZ realizes al ower EQE of 21.7 %i nt he doped OLED,i ts non-doped device shows asuperior EQE of 5.2 %with adeep red/NIR emission at peak of 680 nm.

Quinoxaline 1,4-di-N-oxides (QdNOs) have manifold biological properties, including antimicrobial, antitumoral, antitrypanosomal and antiinflammatory/antioxidant activities. These diverse activities endow them broad applications and prospects in human and veterinary medicines. As QdNOs arouse widespread interest, the evaluation of their medicinal chemistry is still in progress. In the meantime, adverse effects have been reported in some of the QdNO derivatives. For example, genotoxicity and bacterial resistance have been found in QdNO antibacterial growth promoters, conferring urgent need for discovery of new QdNO drugs. However, the modes of actions of QdNOs are not fully understood, hindering the development and innovation of these promising compounds. Here, QdNOs are categorized based on the activities and usages, among which the antimicrobial activities are consist of antibacterial, antimycobacterial and anticandida activities, and the antiprotozoal activities include antitrypanosomal, antimalarial, antitrichomonas, and antiamoebic activities. The structure-activity relationship and the mode of actions of each type of activity of QdNOs are summarized, and the toxicity and the underlying mechanisms are also discussed, providing insight for the future research and development of these fascinating compounds.

D–A–D′ AIEgens exhibit dual emission involving a blue TADF (monomer) and an orange TADF/RTP (dimer), which are switchable via aggregation-state engineering, and demonstrate high contrast MCL as well as white EL emission with high CRI.

While monochrome organic light‐emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) emitters have achieved over 30% external quantum efficiencies (EQEs), all‐TADF white OLEDs (WOLEDs) are still lagging behind. Herein, a simple system based on two color‐complementary TADF emitters is exploited to realize high‐performance WOLEDs. By doping a high‐performance orange–red TADF fluorophor (BPPZ‐DPXZ) into a blue TADF host (DBFCz‐Trz), energy transfer, and triplet‐to‐singlet conversion in the host‐dopant system can be optimized to simultaneously achieve full exciton utilization and color balance. With this design, all‐TADF single‐emitting‐layer WOLEDs with a maximum EQE up to 32.8% are demonstrated. This high efficiency surpasses EQEs of reported WOLEDs based on both TADF as well as phosphorescence. It is expected that this finding can provide new insight for designing highly efficient all‐TADF WOLEDs.

No abstract

Resonance interaction between a molecular transition and a confined electromagnetic field can lead to weak or strong light-matter coupling. Considering the substantial exciton–phonon coupling in thermally activated delayed fluorescence (TADF) materials, it is thus interesting to explore whether weak light-matter coupling can be used to redistribute optical density of states and to change the rate of radiative decay. Here, we demonstrate that the emission distribution of TADF emitters can be reshaped and narrowed in a top-emitting organic light-emitting device (OLED) with a weakly coupled microcavity. The Purcell effect of weak microcavity is found to be different for TADF emitters with different molecular orientations. We demonstrate that radiative rates of the TADF emitters with vertical orientation can be substantial increased in weakly coupled organic microcavity. These observations can enhance external quantum efficiencies, reduce efficiency roll-off, and improve color-purities of TADF OLEDs, especially for emitters without highly horizontal orientation.

Research data are not shared.

BACKGROUND: Natural deep eutectic solvents (NADESs), a class of green solvents which completely accords to 12 principles of green chemistry, have proven to have great potential applications in enzymatic reactions. Despite strong interest, the role of NADESs in these processes, and the molecular interaction between enzymes and NADESs, still remain ambiguous. In the present study, the stability and activity of Candida Antarctica lipase B (CALB) were studied, and the mechanism by which CALB was activated in NADESs was explored systematically from both molecular-and macroscopic-scale perspectives. RESULTS:The results suggested that the activity of CALB in all NADESs was significantly higher than that of the control (ethanol). Moreover, the stability of CALB increased to 115.48 ± 1.36% and 108.54 ± 1.26% in betaine-glycerin (B-Gly) and choline chloride-glycerol (C-Gly), but decreased to 91.69 ± 3.26% and 92.31 ± 3.36% in betaine-xylitol (B-X) and choline chloride-xylitol (C-X), respectively. The results of circular dichroism (CD), fluorescence spectroscopy and molecular dynamics studies (MD) indicated that there was no significant change in the secondary structure of CALB. Furthermore, the results of MD provide some information supporting that CALB was stabilized by the hydrogen(H)-bonding interaction between surface amino residues of CALB and NADESs and was activated via the H-bonding interaction between substrate and NADESs in the acyl-binding pocket. CONCLUSION: The mechanism by which CALB was activated and stabilized via the H-bonding interactions in NADESs wasrevealed in the present study. This provides a scientific basis from which to further explore the potential application of NADESs in enzymatic reactions in food engineering and health-related fields.