Efficient and Stable Red Perovskite Light-Emitting Diodes with Operational Stability >300 h.

The long-term operational stability of perovskite light-emitting diodes (PeLEDs), especially red PeLEDs with only several hours typically, has always faced great challenges. Stable β-CsPbI nanocrystals (NCs) are demonstrated for highly efficient and stable red-emitting PeLEDs through incorporation of poly(maleic anhydride-alt-1-octadecene) (PMA) in synthesizing the NCs. The PMA can chemically interact with PbI in the precursors via the coupling effect between O groups in PMA and Pb to favor crystallization of stable β-CsPbI NCs. Meanwhile, the cross-linked PMA significantly reduces the Pb anti-site defect on the surface of the β-CsPbI NCs. Benefiting from the improved crystal phase quality, the photoluminescence quantum yield for β-CsPbI NCs films remarkably increases from 34% to 89%. The corresponding red-emitting PeLEDs achieves a high external quantum efficiency of 17.8% and superior operational stability with the lifetime, the time to half the initial electroluminescence intensity (T ) reaching 317 h at a constant current density of 30 mA cm .