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To broaden the scope of van der Waals 2D magnets, we report the synthesis and magnetism of covalent 2D magnetic Cr 2 Te 3 with a thickness down to one-unit-cell. The 2D Cr 2 Te 3 crystals exhibit robust ferromagnetism with a Curie temperature of 180 K, a large perpendicular anisotropy of 7 × 10 5 J m −3 , and a high coercivity of ∼ 4.6 kG at 20 K. First principles calculations further show a transition from canted to collinear ferromagnetism, a transition from perpendicular to in-plane anisotropy, and emergent half-metallic behavior in atomically-thin Cr 2 Te 3 , suggesting its potential application for injecting carriers with high spin polarization into spintronic devices. IMPACT STATEMENTA T C of 180 K, a perpendicular anisotropy of 7 × 10 5 J m −3 , and a high coercivity of ∼ 4.6 kG were achieved in covalent Cr 2 Te 3 2D ferromagnets.

The electron-transporting material (ETM) is one of the key factors to determine the efficiency and stability of organic light-emitting diodes (OLEDs). A novel ETM with a "(Acceptor) n -Donor-(Acceptor) n " ("(A) n -D-(A) n ") structure, 2,7-di([2,2′:6′,2″-terpyridin]-4′-yl)-9,9′-spirobifluorene (27-TPSF), is synthesized by combining electron-withdrawing terpyridine (TPY) moieties and rigid twisted spirobifluorene, in which the TPY moieties facilitate electron transport and injection while the spirobifluorene moiety ensures high triplet energy (T 1 = 2.5 eV) as well as enhances glass transition temperature (T g = 195 °C) for better stability. By using tris[2-(p-tolyl)pyridine]iridium(III) (Ir(mppy) 3 ) as the emitter, the 27-TPSF-based device exhibits a maximum external quantum efficiency (η ext, max ) of 24.5%, and a half-life (T 50 ) of 121, 6804, and 382 636 h at an initial luminance of 10 000, 1000, and 100 cd m −2 , respectively, which are much better than the commercialized ETM of 9,10-bis(6-phenylpyridin-3-yl)anthracene (DPPyA). Furthermore, a higher efficiency, a η ext, max of 28.2% and a maximum power efficiency (η PE , max ) of 129.3 lm W −1 , can be achieved by adopting bis(2-phenylpyridine)iridium(III) (2,2,6,6-tetramethylheptane-3,5-diketonate) (Ir(ppy) 2 tmd) as the emitter and 27-TPSF as the ETM. These results indicate that the derivative of TPY to form "(A) n -D-(A) n " structure is a promising way to design an ETM with good comprehensive properties for OLEDs.

A novel high-performance deep-blue emitting material TPEA that combines the merits of AIE and TTF plus HLCT is demonstrated.

Realizing van der Waals (vdW) epitaxy in the 80's represents a breakthrough that circumvents the stringent lattice matching and processing compatibility requirements in conventional covalent heteroepitaxy. However, due to the weak vdW interactions, there is little control over film qualities by the substrate. Typically, discrete domains with a spread of misorientation angles are formed, limiting the applicability of vdW epitaxy. Here we report the epitaxial growth of monocrystalline, covalent Cr5Te8 2D crystals on monolayer vdW WSe2 by chemical vapor deposition, driven by interfacial dative bond formation. The lattice of Cr5Te8, with a lateral dimension of a few ten microns, is fully commensurate with that of WSe2 via 3 × 3 (Cr5Te8)/7 × 7 (WSe2) supercell matching, forming a single-crystalline moiré superlattice. Our work has established a conceptually distinct paradigm of thin film epitaxy termed "dative epitaxy", which takes full advantage of covalent epitaxy with chemical bonding for fixing the atomic registry and crystal orientation, while circumventing its stringent lattice matching and processing compatibility requirements; conversely, it ensures the full flexibility of vdW epitaxy, while avoiding its poor orientation control. Cr5Te8 2D crystals grown by dative epitaxy exhibit square magnetic hysteresis, suggesting minimized interfacial defects that can serve as pinning sites.

Positional isomerism of “(A)n–D–(A)n” type electron transport materials which combine spirobifluorene with terpyridine moieties for long-lived and highly efficient TADF-PhOLEDs.

A chrysene derivative, BPCC (6,12-bis(9-phenyl-9H-carbazol-3-yl)chrysene), possessing high thermal stability with a high glass transition temperature (Tg = 181 °C) was synthesized.

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