Side-Chain-Promoted Polymer Architecture Enabling Stable Mixed-Halide Perovskite Light-Emitting Diodes

Mixed-halide perovskite nanocrystals (PeNCs) featuring bandgap-tunable luminescence with narrow bandwidth have emerged as promising electroluminescent materials for light-emitting diodes (LEDs) to satisfy the color standard of Rec. 2100. However, the phase segregation of mixed-halide perovskites severely restricts the spectral stability and lifetime of perovskite LEDs (PeLEDs). Here, we report that the introduction of multifunctional side-chain-promoted polymer architectures in the synthesis of I/Br-mixed PeNCs to suppress halide segregation and enable electroluminescent stability of the PeLEDs up to ∼2500 min, which is the longest to our knowledge. Meanwhile, the PeLEDs exhibit the pure-red electroluminescence spectrum with Commission Internationale de l'Eclairage coordinates (0.705, 0.292) at one of the highest external quantum efficiencies reported to date, 23.6%. Fundamentally, the as-proposed polymer ligand architecture simultaneously offers long-term nanocrystal dispersion, good charge transport, defect elimination, and phase segregation suppression. Overall, the work demonstrates the potential of the multifunctionalized polymer ligands for developing high-performance PeLEDs toward practical applications.