No abstract

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.

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

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.