All-Solution-Processed Sky-Blue Perovskite Electroluminescence Device via Integrated Supramolecular Host–Guest Post-Treatment

All-solution-processed perovskite optoelectronic devices are promising for scalable, sustainable manufacturing, yet their performance remains inferior to vacuum-deposited counterparts because solvents used for subsequent charge transport layers often damage the underlying emissive layer. Herein, we find that when fabricating the electron transport layer (ETL) on sky-blue quasi-2D perovskite films using solution processing, even nonpolar solvents degrade luminescence properties and surface morphology, primarily due to the loss of organic ligands and additives. To overcome this challenge, we develop a supramolecular host–guest complexation strategy that predissolves these organic components in nonpolar solvents and incorporates them directly into the ETL processing sequence. Using this method, we achieve a sky-blue PeLED with an external quantum efficiency of 14.75% and a maximum luminance of 8740 cd m –2 . This work provides a versatile and promising route to high-performance, all-solution-processed PeLEDs.