Efficient Perovskite Light-Emitting Diodes Enabled by Nickel Acetate Interlayer

Metal halide perovskite light-emitting diodes (Pero-LEDs) have gained great attention due to their promising applications in lighting and displays. However, in their conventional three-layered sandwich structure, some undeserved carrier behaviors, such as imbalanced carrier injection, severe carrier loss, and unstable recombination zone, limit the device's performance. Herein, a four-layered design by inserting a nickel acetate (Ni(OAc) 2 ) interlayer between the emitter and hole-transport layer(HTL) to manage carrier behavior and improve radiative recombination efficiency is proposed. Specifically, the Ni(OAc) 2 interlayer is poorly conductive and can partially block the hole injection, making the hole-electron injection more balanced. And the Ni(OAc) 2 interlayer avoids the direct contact between the perovskite emitter and hole transporter, reducing the interfacial carrier quenching. Moreover, the Ni(OAc) 2 interlayer inhibits the electron-migrated recombination at the hole transporter interface, confining the carrier recombination zone in the emitter layer. As a result, the corresponding Pero-LEDs achieve a maximum external quantum efficiency ( EQE max ) of 24.6% with good reproducibility, showing an average EQE max of over 20%.