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 (EQEmax) of 24.6% with good reproducibility, showing an average EQEmax of over 20%. In the typically three-layer structure, some undeserved carrier behaviors, such as imbalanced carrier injection, severe carrier loss, and unstable recombination zone, limit the device performance. Inserting an inert nickel acetate (Ni(OAc)2) interlayer between perovskite and hole transporter can prevent the non-radiative quenching at the interface, balance the charge carriers, confine the carrier recombination zone, and significantly improve the EQE to 24.6%.image