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-CsPbI3 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 PbI2 in the precursors via the coupling effect between O groups in PMA and Pb2+ to favor crystallization of stable β-CsPbI3 NCs. Meanwhile, the cross-linked PMA significantly reduces the PbCs anti-site defect on the surface of the β-CsPbI3 NCs. Benefiting from the improved crystal phase quality, the photoluminescence quantum yield for β-CsPbI3 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 (T50 ) reaching 317 h at a constant current density of 30 mA cm-2 .