Computation-assisted design of stable quasi-2D organic sulfate perovskite NIR light-emitting diodes

<h2>Summary</h2> Quasi-two-dimensional (2D) perovskite light-emitting diodes (PeLEDs) exhibit high red-emission efficiency but poor stability due to defect-mediated recombination and ion migration in hybrid perovskite nanocrystals (NCs). Here, we present a solvent-free mechanochemical synthesis of red-emitting quasi-2D (OA)₂(MA)₂Pb₂I₈(PbSO₄) NCs using dioctylammonium sulfate (DOS), guided by first-principles calculations. The DOS ligand promotes PbSO₄ layer formation, which passivates defects, suppresses ion migration, and enhances humidity resistance. Unlike iodide-based octylammonium iodide (OAI) devices that degrade rapidly and emit only at 763 nm, DOS-stabilized PeLEDs show dual emission at 651 and 763 nm, indicating improved phase stability. The devices achieve a peak luminance of 7,039 cd/cm² and an external quantum efficiency of 9.76%, retaining over 60% of initial EQE after 100 days, markedly outperforming conventional OAI-MAPbI₃ PeLEDs (<20%). These results demonstrate that sulfate passivation provides a simple and scalable route to robust, durable red-emitting quasi-2D PeLEDs, offering a promising strategy for high-performance optoelectronic devices.