Enhanced Electroluminescence and Stability of Sky-Blue Perovskite Light-Emitting Diodes

Although remarkable breakthroughs have been witnessed in the field of perovskite light-emitting diodes (PeLEDs), achieving efficient and stable blue PeLEDs still remains as a critical challenge to towards commercial applications. Inspired by the protection effect and water-repellent properties of swan feathers, 2H,2H,3H,3H-heptadecafluoroundecanoic acid (HFUA) has been designed as adsorbed functional molecule for blue perovskites, which can simultaneously enhance the electroluminescence performance and moisture stability. The HFUA molecule features a long-chain structure where the carboxylic acid group acts as an anchor, coordinating with undercoordinated lead atoms in blue perovskites. The fluorine atoms at the opposite end of the chain form ionic bonds with the halogen octahedron, thereby stabilizing the octahedral structure. In addition, HFUA adsorption lowers the adsorption energy of organic spacers on the perovskite lattice, optimizing the reduced-dimensional phase distribution to facilitate smooth exciton transfer. Furthermore, the unique molecular structure of HFUA, rich in fluorine atoms, enhances the hydrophobicity of the perovskite surface, effectively inhibiting moisture penetration and preventing perovskite hydrolysis. The target blue PeLEDs obtain a maximum external quantum efficiency of 22.88 % at 490 nm and exhibit greatly improved air stability under humid and high-temperature conditions. Our findings provide a unique and effective strategy for producing efficient and stable blue PeLEDs.