Blue perovskite light-emitting diodes (LEDs): A minireview

Metal perovskite halides have led to the development of light-emitting diodes due to their excellent optical and electrical properties. However, compared to near-infrared, red, and green perovskite light-emitting diodes, blue-emitting light-emitting diodes lag far behind in development due to poor stability and low quantum efficiency. In this review, the latest advances in blue perovskite light-emitting diodes are described, including three-dimensional perovskites, two-dimensional/quasi-two-dimensional perovskites, and perovskite nanocrystals. In the three-dimensional perovskite section, the choices of halide perovskite composition, electron transport layer and hole transport layer enable tunable light emission from sky blue to dark blue. In the two-dimensional/quasi-two-dimensional perovskite discussion, the co-surfactant colloid chemistry, and component engineering precisely control the stacking number, which produces a significant blue shift by quantum confinement effects. In the perovskite nanocrystal section, the selection of organic ligands and inorganic passivation are the key strategies to keep the nanocrystal structure stable and fully passivate surface defects. In each section, the present situation and major challenges are overviewed. Next, the evolutions of the methods to overcome these challenges and the most important breakthroughs are highlighted. In conclusion, future directions that may improve the performance of blue perovskite light-emitting diodes are discussed.