Perovskite Light-emitting diodes (PeLEDs) have emerged as a promising technique for future high-definition displays due to their outstanding electroluminescent characters. However, the development of blue PeLEDs toward practical applications is seriously hindered by their inferior performance, which mainly arises from the detrimental halide ionic behavior and thus severe nonradiative recombination in mixed-halide blue perovskite materials. Herein, efficient sky-blue PeLEDs featuring spectrally stable emission at 483 nm are realized by employing bifunctional passivators of Lewis-base benzoic acid anions and alkali metal cations to simultaneously passivate the under-coordinated lead atoms and suppress halide ion migration. A decent external quantum efficiency (EQE) of 16.58% and a maximum EQE of 18.65% are achieved, which is further boosted to 28.82% through the optical outcoupling enhancement. This work demonstrates unique insight into the generality and individuality of this category of benzoates and puts forward a feasible guidance in choosing appropriate additives for efficient perovskite materials.

Metal halide perovskite materials hold great potential as a core element in full‐color display and lighting applications due to their unique optoelectronic properties, such as high photoluminescence efficiency, good color purity, tunable bandgap, and low‐temperature solution processability. However, the performance of blue perovskite light‐emitting diodes (PeLEDs) lags far behind their red and green counterparts, impeding their practical use. Herein, the recent progress on blue PeLEDs based on different restrictions and some feasible strategies to improve luminescence efficiency and stability are summarized. The methods to optimize blue‐emission perovskite materials with different dimensions are addressed. The major factors affecting luminescence stability, the approaches to balance charge injection and minimize the optical loss are also discussed. Several problems in blue PeLEDs, particularly the toxicity of lead‐based perovskites and the alternative solutions of lead‐free perovskites, are emphasized. Finally, the perspective of future development in blue PeLEDs is provided.

Halide perovskite materials are emerging as a new promising semiconductor display material owing to their excellent optical and electrical properties. Highly efficient blue perovskite light-emitting diodes (PeLEDs) are the basis for full-color displays and solid-state lighting applications, but their efficiency and stability still lag far behind the red and green analogs. This review focuses on the key effect factors and novel strategies for blue emission PeLEDs. In detail, first effective strategies to obtain blue emission perovskite are discussed, and then the recent progress and strategies in blue emission PeLEDs, including the physical properties and significant improvements based on different structural perovskite materials are systematically elucidated. Finally, the main challenges relating to efficiency, stability, lead toxicity, and fabrication techniques in blue emission PeLEDs are summarized, and the promising research avenues in the future are discussed.

Metal halide perovskite (MHP) materials have shown great advantages for the next-generation optoelectronic devices, especially for light-emitting diodes (LEDs), on account of their outstanding photoelectric properties and facile solution processability. However, the performances of red perovskite LEDs (PeLEDs) are not ready for commercialization, presumably due to the instability both of the emission spectra and operation conditions, and the toxicity of lead ions. In this review, the structures, physical properties, and preparation approaches of red emissive perovskite materials are first introduced, including 3D bulk perovskites, 2D and quasi-2D perovskites, and colloidal perovskite nanocrystals (NCs). In addition, several strategies that contribute to the recent development and achievement of red PeLEDs are summarized in detail, mainly involving component engineering, dimension, and phase distribution modulation, ligand engineering, additive engineering, interfacial engineering, and strategies for the light out-coupling device structure. Moreover, the challenges and corresponding solutions are discussed from three aspects of spectral stability, operational stability, and lead-free red PeLEDs. Finally, the conclusion and outlook on the promising future of the red PeLEDs are raised.

Despite tremendous developments in the luminescene performance of perovskite light-emitting diodes (PeLEDs), the brittle nature of perovskite crystals and their poor crystallinity on flexible substrates inevitably lead to inferior performance. Inspired by pangolins' combination of rigid scales and soft flesh, we propose a bionic structure design for self-healing flexible PeLEDs by employing a polymerassisted crystal regulation method with a soft elastomer of diphenylmethane diisocyanate polyurethane (MDI-PU). The crystallinity and flexural strain resistance of such perovskite films on plastics with silver-nanowire-based flexible transparent electrodes are highly enhanced. The detrimental cracks induced during repeated deformation can be effectively self-healed under heat treatment via intramolecular/intermolecular hydrogen bonds with MDI-PU. Upon collective optimization of the perovskite films and device architecture, the blue-emitting flexible PeLEDs can achieve a record external quantum efficiency of 13.5% and high resistance to flexural strain, which retain 87.8 and 80.7% of their initial efficiency after repeated bending and twisting operations of 2000 cycles, respectively.