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.

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Herein, we have introduced rare-earth cations Tb and Eu into CsPbBr QDs glass by conventional melt-quenching. Rare-earth cations like Tb emit green light, causing the main peak of bromide lead cesium to exhibit some redshift, owing to the energy transfer between CsPbBr and Tb. To achieve adjustable light, Eu emits red light, which was doped in this glass with different proportions to solve the problem of red deficiency. More importantly, Tb and Eu co-doped CsPbBr QDs glass shows a series of desirable characteristics due to the energy transfer between Tb and Eu. Interestingly, the blue light radiated by blue chip can excite Tb, Eu, and CsPbBr perovskite effectively. We acquired high-performance white light-emitting diodes with color-rendering index, color coordinate transformation, and luminous efficiency of 85.7, 4945 K, and 63.21 lm/W under the current of 20 mA. This acquired Tb, Eu co-doped CsPbBr QDs glass proved the significant feasibility of luminescent materials in solid warm light source.

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