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Metal halide perovskites have attracted extensive attention in next-generation solid-state lighting and displays due to their fascinating optoelectronic properties. However, the toxicity of lead (Pb) impedes their practical application. Herein, we report an efficient Zn-alloyed quasi-two-dimensional (quasi-2D) pure-red perovskite light-emitting device (PeLED) by introducing zinc ions (Zn2+) into the perovskite lattice and partially substituting Pb2+. The substitution of Zn2+ is confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, grazing-incidence wide-angle X-ray scattering, and transmission electron microscopy measurements. In addition, the vacancy defect density of Pb and the halogen is reduced by the introduction of Zn2+ in the PEA2(Cs0.3MA0.7)2(ZnxPb1-x)3I10 perovskite system, which leads to a more ordered crystal orientation, compact morphology, and increased photoluminescence quantum efficiency. Benefiting from the improved photoelectric properties, a maximum EQE of 9.5% and a luminescence of 453 cd m-2 are achieved for the Zn-alloyed PeLEDs, with a maximum emission peak of 658 nm and stable electroluminescence spectra under various applied biases.

Quasi-2D perovskites have long been considered to have favorable "energy funnel/cascade" structures and excellent optical properties compared with their 3D counterparts. However, most quasi-2D perovskite light-emitting diodes (PeLEDs) exhibit high external quantum efficiency (EQE) but unsatisfactory operating stability due to Auger recombination induced by high current density. Herein, a synergetic dual-additive strategy is adopted to prepare perovskite films with low defect density and high environmental stability by using 18-crown-6 and poly(ethylene glycol) methyl ether acrylate (MPEG-MAA) as the additives. The dual additives containing COC bonds can not only effectively reduce the perovskite defects but also destroy the self-aggregation of organic ligands, inducing the formation of perovskite nanocrystals with quasi-core/shell structure. After thermal annealing, the MPEG-MAA with its CC bond can be polymerized to obtain a comb-like polymer, further protecting the passivated perovskite nanocrystals against water and oxygen. Finally, state-of-the-art green PeLEDs with a normal EQE of 25.2% and a maximum EQE of 28.1% are achieved, and the operating lifetime (T50 ) of the device in air environment is over ten times increased, providing a novel and effective strategy to make high efficiency and long operating lifetime PeLEDs.

Bumped bamboo carbon nanotubes (carbon nanosprouts) were directly synthesized on calcined stainless steel by chemical vapor deposition. Using a mixture of CO and H2 as the carbon precursor, dense carbon nanosprouts were formed on the surfaces of stainless-steel wire without external catalyst addition. The air calcination favours the formation of iron oxide nanoparticles with relatively small diameters, catalysing the synthesis of carbon nanosprouts with comparable trunk diameters. Transmission electron microscopy analysis shows that Fe2.5C is the active catalyst phase and catalyst deactivation is caused by graphitic layer encapsulation. The enhanced carbon precipitation of Fe catalyst, promoted by the carbon source dissociation or its synergism with other metal, is responsible for the generation of nanosprouts.