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Perovskite light-emitting diodes (LEDs) show promises for next-generation displays owing to their excellent luminescent properties and low cost. Despite substantial progress with green- and red-emitting devices, the development of efficient blue perovskite LEDs has lagged behind. Here we demonstrate efficient blue perovskite LEDs based on a mixed two-dimensional–three-dimensional perovskite and a multifunctional ionic additive that enables control over the reduced-dimensional phases, non-radiative recombination channels and spectral stability. We report a series of devices that emit efficient electroluminescence from mixed bromide/chloride quasi-three-dimensional regions, with external quantum efficiencies of up to 21.4% (at a luminance of 22 cd m–2 and emission peak at 483 nm), 13.2% (at a luminance of 2.0 cd m–2 and emission peak at 474 nm) and 7.3% (at a luminance of 6 cd m–2 and emission peak at 464 nm). Devices show a nearly 30-fold increase in operational stability compared with control LEDs, with a half-lifetime of 129 min at an initial luminance of 100 cd m–2. Our findings demonstrate the performance of blue perovskite LEDs close to that of state-of-the-art blue organic LEDs and inorganic quantum dot LEDs and provide a new approach to design multifunctional molecules to boost the performance of perovskite optoelectronic devices. Addition of a multifunctional ionic additive in mixed two-dimensional–three-dimensional bromide/chloride perovskites enables efficient blue perovskite LEDs with external quantum efficiency of up to 21.4% and half-lifetime of 129 min at an initial luminance of 100 cd m–2. [ABSTRACT FROM AUTHOR]

Understanding deformation mechanisms in semi-crystalline polymers during stretching is useful for guiding the processing of high-performance polymer products. In the current work, molecular dynamics simulations were performed to investigate the crystal changes in crystallized polyethylene/carbon nanotube nanocomposites during uniaxial stretching. Both crystal fragmentation and melting occur at low strains. Crystals with small sizes are easier to melt, while those with large sizes would break into smaller crystals. In addition, crystals in interfacial regions are more likely to melt or break due to the orientation motion of carbon nanotubes. It was also found that the recrystallization process is closely related to the stretch-induced orientation of chain segments. After orientation of chain segments along stretching direction is saturated, the recrystallization of highly oriented segments dominates. The current simulation findings are effective complements to the theories of the mechanism of plastic deformation in semicrystalline polymers. [ABSTRACT FROM AUTHOR]

The ZCuSn10P1 copper alloy bushings were prepared by thixotropic back-extruded casting. And the effects of the solution treatment on the microstructure and properties of bushings were studied. The results showed that the microstructures were relatively uniform when the bushes were solution treated at 690 °C for 60 min-100 min. With the extension of solution treatment time, the average grain size of primary phase increased, and a small amount of Cu3P phase precipitated and distributed along the grain boundaries. The Sn element in the matrix gradually diffused into the intergranular structure to form the Cu41Sn11 phase. The tensile strength and elongation first increased and then decreased with increasing solution treatment time. [ABSTRACT FROM AUTHOR]