Enhancing Efficiency of Quasi-2D PeLEDs Through Anti-Solvent Treatment-Induced Phases Modulation

Quasi-2D perovskite has drawn considerable attention for application in perovskite light-emitting diodes (PeLEDs) due to their higher exciton binding energy and moisture resistance. However, the inhomogeneous distribution of phases formed in spin-coated quasi-2D perovskite films inevitably leads to energy transfer loss, limiting the emission performance. Here, we systematically investigated the phases modulation behavior for a series of anti-solvent with different polarity -namely, the toluene (TO), diethyl ether (DE), chlorobenzene (CB), anisole (AN), ethyl acetate (EA). Due to the strong hydrogen bonding interaction between EA and organic spacer cations, it will hinder the organic and [PbBr₆]⁴⁻ combination. The crystallization rate of intermedia phases slows, resulting in a large proportion of high-n phases formation subsequently. As a result, an efficient energy cascade is ensured with a narrow distribution centered around the desired phases. Leveraging these insights, we achieved PeLEDs with improved external quantum efficiency (EQE) of 4.21%, 7.11%, and 8.77%, corresponding to ∼490 nm, ∼497 nm, and ∼503 nm emissions, respectively. Furthermore, the anti-solvent treatment strategy provides a guide to regulate the phase distribution for eliminating energy transfer loss to fabricate efficient quasi-2D PeLEDs.