Improved Charge Balance in Green Perovskite Light-Emitting Diodes with Atomic-Layer-Deposited AlO.

Perovskite light-emitting diodes (LEDs) have experienced a rapid increase in efficiency over the last several years and are now regarded as promising low-cost devices for displays and communication systems. However, it is often challenging to employ ZnO, a well-studied electron transport material, in perovskite LEDs due to chemical instability at the ZnO/perovskite interface and charge injection imbalance caused by the relatively high conductivity of ZnO. In this work, we address these problems by depositing an ultrathin AlO interlayer at the ZnO/perovskite interface, allowing the fabrication of green-emitting perovskite LEDs with a maximum luminance of 21 815 cd/m. Using atomic layer deposition, we can precisely control the AlO thickness and thus fine-tune the electron injection from ZnO, allowing us to enhance the efficiency and operational stability of our LEDs.