Regulating the continuous and concentrated distribution of Quasi-2D perovskite phases to achieve Sky-Blue Light-Emitting diodes with efficiency approaching 17%

Blue perovskite light-emitting diodes (PeLEDs) are increasingly crucial for manufacturing high-definition fullcolor displays due to their outstanding electroluminescent properties. Quasi-two-dimensional (quasi-2D) perovskite stands out as the most promising material for blue light-emitting layer, given its robust quantum/ dielectric confinement. In this study, we present the preparation of PeLEDs with a tunable blue emission wavelength using pure bromide perovskite components by adjusting the content of halogenated organic ammonium bromide [2-bromoethylamine hydrobromide (BEABr)]. The bifunctional ligand BEABr not only achieves an excellent phase distribution of quasi-2D perovskite but also reduces the weak van der Waals gap between individual perovskite layers, facilitating effective energy transfer in perovskite films. Additionally, the bifunctional groups passivate perovskite defects and inhibit phase separation, leading to efficient and stable skyblue luminescence. The BEABr-doped sky-blue PeLED demonstrated superior device performance, achieving a maximum external quantum efficiency of 16.98 % at 493 nm. This work serves as inspiration for further exploration of efficient and stable commercial blue PeLED devices.