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Electrode materials with two-dimensional (2-D) structures have attracted tremendous attention because they can exhibit many excellent electrochemical and chemical properties. Herein, we present a simple and general self-template-etched solution route to fabricate 2-D γ-manganese sulfide (γ-MnS) nanoplates using Mn3[Fe(CN)6]2 as a sacrificial template and Mn source. Detailed analysis and experimental results indicate that the ethylene glycol/H2O-assisted hydrothermal system and the unique metal frameworks are vitally important for the formation, structure, and morphology of plate-shaped γ-MnS during the sulfidation process. By controlling the growth and etching process, a possible growth mechanism was proposed to interpret the formation of 2D γ-MnS nanoplates. As a promising anode material for pseudocapacitors, the γ-MnS nanoplate sample not only delivers a good specific capacity of 378 F g−1 at 0.2 A g−1 and high rate capability in neutral solution, but it also displays an excellent stable performance, with only about 10% loss after continuous charge–discharge cycling for 4000 cycles at 1.0 A g−1. The method appears to be a new way for using the sulfuration transformation matrix to obtain other two-dimensional transition metal compounds. [ABSTRACT FROM AUTHOR]

White organic light-emitting diodes (WOLEDs) based on all thermally activated delayed fluorescence (TADF) emitters are especially attractive due to the merits of high efficiency and low cost. Novel TADF emitters (TFM-QP and CN-QP) were developed by selecting 6-(trifluoromethyl)quinoxaline or 6-(cyano)quinoxaline as the electron acceptor and phenoxazine as the electron donor. Aggregation induced emission is detected. Small singlet and triplet energy splitting values of 0.03–0.04 eV and long fluorescence lifetimes of 1.6–5.0 μs confirm their TADF nature. The chromaticity of monochromic OLEDs with TFM-QP and CN-QP as doped emitters was adjustable from yellow to orange–red by varying the doping concentration, and the yellow OLEDs exhibit external quantum efficiencies (ηext) of 14.4% and 9.7% at a low doping level. Full-TADF WOLEDs were fabricated using TFM-QP or CN-QP in combination with the sky-blue TADF emitter DMAC-DPS. The single-emitting-layer doped warm-white OLED (CN-QP:DMAC-DPS) exhibits excellent performance with a low turn-on voltage of 2.8 V, a stable color rending index (CRI) of 72, and high efficiencies of 48.22 cd A−1, 50.47 lm W−1, and 20.16%, which should be the highest efficiency records ever reported for full-TADF warm-white OLEDs so far. The non-doped full-TADF WOLED with an emitting layer structure of DMAC-DPS/TFM-QP/DMAC-DPS achieves a high CRI of 86 and a moderate ηext of 8.7%. [ABSTRACT FROM AUTHOR]

The largely twisted intramolecular charge transfer (TICT) framework is the most commonly adopted strategy for constructing thermally activated delayed fluorescence (TADF) molecules. By increasing the dihedral angle between the donor and acceptor, a small singlet–triplet energy splitting (ΔEST), high reverse intersystem crossing rate (kRISC) and large proportion of delayed emission can be achieved simultaneously. Five twisted molecules, tCPT, Ph-tCPT, o-PhCz-tCPT , p-PhCz-tCPT and 3-PhCz-tCPT, are designed and synthesized combining cyaphenine and 3,6-di-tert-butyl-9H-carbazole or its derivatives. Phenyl (Ph) and N-phenyl carbazole (N-PhCz) are introduced to the 1-site of 3,6-di-tert-butyl-9H-carbazole to design the donor units, with the expectation to tune the dihedral angle between the donor and acceptor and the frontier molecular orbital distribution. As a result, the ΔEST decreases from 0.30 eV for tCPT to 0.20 eV for 3-PhCz-tCPT, and the delayed fluorescence (DF) proportion increases from 19.5% for tCPT to 31.9% and 37.3% for o-PhCz-tCPT and 3-PhCz-tCPT. Organic light-emitting diodes (OLEDs) using these molecules as doped emitters exhibit pure blue emission with the peaks at 456–466 nm. The emitters with higher DF proportions show higher electroluminescence efficiencies, e.g. 13.8 and 16.4 cd A−1 for o-PhCz-tCPT and 3-PhCz-tCPT devices, respectively, representing an efficiency increase by 10% relative to tCPT. It is demonstrated that incorporation of bulky substituents at the 1-site of carbazole is an effective and practical way to facilitate RISC and enhance the DF proportion of blue TADF materials. [ABSTRACT FROM AUTHOR]

Blue iridium phosphors are always precious and desirable for both fundamental research and industrial applications in organic light-emitting diodes (OLEDs). Three heteroleptic cyclometalated iridium(III) complexes, namely, Ir1, Ir2 and Ir3, incorporating 2-(3,5-bis(trifluoromethyl)phenyl)-pyrimidine (tfmphpm) or 2-(2,4-difluorophenyl)-pyrimidine (dfppm) as the main ligand, and 2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridine (fppz) or 2-(5-(4-(trifluoromethyl)phenyl)-2H-1,2,4-triazol-3-yl)pyridine (Htaz) as the ancillary ligand, were developed for application in OLEDs. Owing to the introduction of the strong-field CF3-containing ancillary ligand and the incorporation of electron-withdrawing F or CF3 groups on the HOMO-lying C-related aromatic rings of the C^N cyclometalating ligands, the phosphorescence of these Ir(III) complexes peaked at 457–459 nm. In comparison with the well-known commercial sky-blue iridium complex FIrpic (bis(4′,6′-difluorophenylpyridinato) iridium(III) picolinate, 475 nm), the phosphorescence of these complexes is hypsochromically shifted by 16–18 nm, more closely approaching standard blue light. They have high phosphorescence quantum yields in solution. The phosphorescent OLEDs employing these complexes as doped emitters display impressive performance. In particular, the PhOLED based on Ir3 achieves an outstanding maximum external quantum efficiency of 21.23% with Commission Internationale de l'Eclairage (CIE) coordinates of (0.15, 0.26), which is about 27% higher than that of the control device using FIrpic as a dopant (16.63%). [ABSTRACT FROM AUTHOR]