High-Luminance Blue Quasi-2D Perovskite Light-Emitting Diodes by Engineering Polarity-Controlled Solvent-Film Interaction

Blue perovskite light-emitting diodes (PeLEDs) operating in the 460–480 nm spectral range remain limited by insufficient luminance and rapid degradation under high current densities. In quasi-two-dimensional (quasi-2D) perovskite emitters, excessive lower-n phases and organic-rich surface components hinder efficient carrier transport and accelerate nonradiative recombination, leading to early luminance saturation. Here, we demonstrate a polarity-controlled solvent post-treatment that selectively regulates surface-emissive pathways after forming quasi-2D perovskite films without altering the composition. A systematic solvent screening based on solvent-perovskite interactions correlated with dielectric constants identified isopropyl alcohol (IPA) as the ideal post-treatment solvent. IPA treatment facilitates a dynamic redistribution of emission sources from lower-n to more stable higher-n domains. The IPA treatment effectively reduced surface-associated organic species and defect-mediated non-radiative losses while preserving the quasi-2D lattice framework. Consequently, the IPA-treated quasi-2D PeLEDs exhibited a record-high peak luminance of 8,600 cd∙m⁻² at 478 nm, outperforming previously reported blue quasi-2D PeLEDs. This enhancement was complemented by facilitated charge transport and mitigated efficiency roll-off, ultimately resulting in superior operational stability. This work establishes solvent post-treatment as a straightforward and processing-compatible strategy to overcome intrinsic luminance limitations in blue quasi-2D PeLEDs by regulating surface-dominated recombination dynamics under high-current operation.