Stable Tetradentate Gold(III)-TADF Emitters with Close to Unity Quantum Yield and Radiative Decay Rate Constant of up to 2 × 106 s-1 : High-Efficiency Green OLEDs with Operational Lifetime (LT90 ) Longer than 1800 h at 1000 cd m-2.

High maximum external quantum efficiency (EQEmax ), small efficiency roll-offs, and long operational lifetime at practical luminances are three crucial parameters for commercialization of organic light-emitting diodes (OLEDs). To simultaneously achieve these goals, it is desirable to have the radiative decay rate constant (kr ) as large as possible, which, for a thermally activated delayed fluorescent (TADF) emitter, requires both a large S1 →S0 radiative decay rate constant (kr S ) and a small singlet-triplet energy gap (ΔEST ). Here, the design of a class of tetradentate gold(III) TADF complexes for narrowing the ΔEST while keeping the kr S large is reported. The as-synthesized complexes display green emission with close to unity emission quantum yields, and kr approaching 2 × 106 s-1 in thin films. The vacuum-deposited green OLEDs based on 1 and 4 demonstrate maximum EQEs of up to 24 and 27% with efficiency roll-offs of 5.5 and 2.2% at 1000 cd m-2 , respectively; the EQEs maintain high at 10 000 cd m-2 (19% (1) and 24% (4)). A long LT90 device lifetime of 1820 h at 1000 cd m-2 for complex 1 is achieved, which is one of the longest device lifetimes of TADF-OLEDs reported in the literature.

Fabrication of a Solution-Processed White Light Emitting Diode Containing a Single Dimeric Copper(I) Emitter Featuring Combined TADF and Phosphorescence.

Luminescent copper(I) complexes showing thermally activated delayed fluorescence (TADF) have developed to attractive emitter materials for organic light emitting diodes (OLEDs). Here, we study the brightly luminescent dimer Cu2Cl2(P∩N)2 (P∩N = diphenylphosphanyl-6-methyl-pyridine), which shows both TADF and phosphorescence at ambient temperature. A solution-processed OLED with a device structure ITO/PEDOT:PSS/PYD2: Cu2Cl2(P∩N)2/DPEPO (10 nm)/TPBi (40 nm)/LiF (1.2 nm)/Al (100 nm) shows warm white emission with moderate external quantum efficiency (EQE). Methods for EQE increase strategies are discussed.

Gegen Qinlian Decoction Ameliorates Nonalcoholic Fatty Liver Disease in Rats via Oxidative Stress, Inflammation, and the NLRP3 Signal Axis.

Gegen Qinlian Decoction (GQD), a classic Chinese herbal formula, has been widely used in Chinese clinic for centuries and is well defined in treating nonalcoholic fatty liver disease (NAFLD). However, the mechanism action of GQD on NAFLD is still rarely evaluated. The present study aims to investigate the effect of GQD on treatment of NAFLD in rats and to further explore the underlying mechanism. The rat NAFLD model established by high-fat-diet feeding was used in the research. Our results exhibited the liver lesions and steatosis was significantly alleviated in NAFLD rats treated with GQD via Oil Red O and H&E staining. Body weight and liver index in GQD groups were reduced significantly (P < 0.05). Moreover, the biochemical analyzer test results showed that GQD significantly decreased blood lipid levels total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and liver injury indicators alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP), while it increased the level of high-density lipoprotein cholesterol (HDL-C) (P < 0.05). The levels of interferon-ß (IFN-ß), tumor necrosis factor-α (TNF-α), and malondialdehyde (MDA) after the GQD treatment were significantly lower, and then interleukin-2 (IL-2), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) levels were lifted significantly (P < 0.05). Further, GQD blocked the expression of NLRP3, ASC, caspase-1 mRNA, and proteins in the liver tissues significantly (P < 0.05). These findings indicated that GQD can ameliorate the hepatic steatosis and injury of NAFLD. Its possible mechanism involves the modulation of inflammatory cytokines and antioxidative stress and the inhibition of NLRP3 signal axis activation. The results support that GQD may be a promising candidate in the treatment of NAFLD.

High Efficiency Sky-Blue Gold(III)-TADF Emitters*.

Highly efficient sky-blue luminescent gold(III) complexes with emission quantum yields up to 82 %, lifetimes down to 0.67 µs and emission peak maxima at 470-484 nm were prepared through a consideration of pincer gold(III) donor-acceptor complexes. Photophysical studies and time-dependent density functional theory (TDDFT) calculations revealed that the emission nature of these gold(III) complexes is most consistent with TADF. Solution-processed OLEDs with these gold(III) complexes as dopants afforded electroluminescence maxima at 465-473 nm with FWHM of 64-67 nm and maximum external quantum efficiencies (EQEs) of up to 15.25 %. This research demonstrates the first example of gold(III)-OLEDs showing electroluminescence maxima at smaller than 470 nm, and highlights the potential of using gold(III)-TADF emitters in the development of high efficiency blue OLEDs and blue emissive dopant in WOLEDs.

Recent Advances in Metal-TADF Emitters and Their Application in Organic Light-Emitting Diodes.

In this contribution, recent advances in new classes of efficient metal-TADF complexes, especially those of Au(I), Au(III), and W(VI), and their application in OLEDs are reviewed. The high performance (EQE = 25%) and long device operational lifetime (LT95 = 5,280 h) achieved in an OLED with tetradentate Au(III) TADF emitter reflect the competitiveness of this class of emitters for use in OLEDs with practical interest. The high EQE of 15.6% achieved in solution-processed OLED with W(VI) TADF emitter represents an alternative direction toward low-cost light-emitting materials. Finally, the design strategy of metal-TADF emitters and their next-stage development are discussed.

Tetradentate Gold(III) Complexes as Thermally Activated Delayed Fluorescence (TADF) Emitters: Microwave-Assisted Synthesis and High-Performance OLEDs with Long Operational Lifetime.

Structurally robust tetradentate gold(III)-emitters have potent material applications but are rare and unprecedented for those displaying thermally activated delayed fluorescence (TADF). Herein, a novel synthetic route leading to the preparation of highly emissive, charge-neutral tetradentate [C^C^N^C] gold(III) complexes with 5-5-6-membered chelate rings has been developed through microwave-assisted C-H bond activation. These complexes show high thermal stability and with emission origin (3 IL, 3 ILCT, and TADF) tuned by varying the substituents of the C^C^N^C ligand. With phenoxazine/diphenylamine substituent, we prepared the first tetradentate gold(III) complexes that are TADF emitters with emission quantum yields of up to 94 % and emission lifetimes of down to 0.62 µs in deoxygenated toluene. These tetradentate AuIII TADF emitters showed good performance in vacuum-deposited OLEDs with maximum EQEs of up to 25 % and LT95 of up to 5280 h at 100 cd m-2 .

Highly Enantioselective Synthesis Using Prolinol as a Chiral Auxiliary: Silver-Mediated Synthesis of Axially Chiral Vinylallenes and Subsequent (Hetero)-Diels-Alder Reactions.

Using (S)-prolinol as a chiral auxiliary, axially chiral vinylallenes with excellent enantiopurity (up to >99% enantiomeric excess (ee)) were readily prepared from optically pure propargylamines in the presence of AgNO3 under microwave irradiation. Subsequent (hetero)-Diels-Alder reaction of these axially chiral vinylallenes with azodicarboxylates or maleimides on water demonstrates excellent axial-to-point chirality transfer (up to 99% ee).

Thermally Stable Donor-Acceptor Type (Alkynyl)Gold(III) TADF Emitters Achieved EQEs and Luminance of up to 23.4% and 70 300 cd m-2 in Vacuum-Deposited OLEDs.

Thermally stable, strongly luminescent gold-TADF emitters are the clue to realize practical applications of gold metal in next generation display and lighting technology, a scarce example of which is herein described. A series of donor-acceptor type cyclometalated gold(III) alkynyl complexes with some of them displaying highly efficient thermally activated delayed fluorescence (TADF) with Φ up to 88% in thin films and emission lifetimes of ≈1-2 µs at room temperature are developed. The emission color of these complexes is readily tunable from green to red by varying the donor unit and cyclometalating ligand. Vacuum-deposited organic light-emitting diodes (OLEDs) with these complexes as emissive dopants achieve external quantum efficiencies (EQEs) and luminance of up to 23.4% and 70 300 cd m-2, respectively.

Highly Luminescent Pincer Gold(III) Aryl Emitters: Thermally Activated Delayed Fluorescence and Solution-Processed OLEDs.

Herein are described the synthesis, photophysical properties and applications of a series of luminescent cyclometalated AuIII complexes having an auxiliary aryl ligand. These complexes show photoluminescence with emission quantum yields of up to 0.79 in solution and 0.84 in thin films (4 wt % in PMMA) at room temperature, both of which are the highest reported values among AuIII complexes. Thermally activated delayed fluorescence (TADF) is the emission origin for some of these complexes. Solution-processed OLEDs made with these complexes showed sky-blue to green electroluminescence with external quantum efficiencies (EQEs) of up to 23.8 %, current efficiencies of up to 70.4 cd A-1 , and roll-off of down to 1 %, highlighting the bright prospect of AuIII -TADF emitters in OLEDs.

Luminescent Cyclometalated Gold(III) Alkyl Complexes: Photophysical and Photochemical Properties.

A series of luminescent cyclometalated gold(III) complexes having alkyls as auxiliary ligands has been prepared. The alkyl ligand was found to effectively increase the emission quantum yields and lifetimes of luminescent cyclometalated gold(III) complexes by circumventing the population of LLCT excited states that are found in complexes supported by arylacetylide ligands. These gold(III) alkyl complexes exhibit emission quantum yields and lifetimes of up to 0.40 and 180 µs, respectively, in solution at room temperature. The triplet emission color of these complexes is tunable from yellow to sky blue by modifying the cyclometalating ligand.