Synergistic phase regulation and defect passivation for efficient deep-blue quasi-2D perovskite light-emitting diodes

Quasi-two-dimensional (quasi-2D) metal-halide perovskite light-emitting diodes (PeLEDs) have attracted extensive attention for next-generation display and lighting applications, while achieving efficient and stable deep-blue emission below 460 nm remains challenging, primarily attributed to the unfavorable phase distribution severe, trap-assisted nonradiative recombination and ion migration. Herein, the multifunctional defect-passivation strategy by using 3-(N-morpholino)-2-hydroxypropanesulfonic acid (MOPSO) as an additive is investigated. The sulfonate (-SO₃^-) and hydroxyl (-OH) groups in MOPSO enable dual interactions with the perovskite lattice. Specifically, the electron-rich sulfonate group chelates with undercoordinated Pb²⁺ ions, while the hydroxyl group forms hydrogen bonds with halide ions. The synergistic interactions regulate the crystallization process to tailor phase distribution, suppress trap-assisted nonradiative recombination and inhibit ion migration. As a result, the optimized deep-blue PeLEDs exhibit a peak external quantum efficiency of 4.13% and a maximum luminance of 1055 cd/m², with a well-defined electroluminescence peak at 456 nm. Moreover, negligible spectral shift is observed over a wide driving-voltage range, indicating improved operational stability. This work demonstrates a simple molecular engineering strategy for advancing efficient and stable deep-blue quasi-2D PeLEDs.