Manipulated Interface for Enhanced Energy Cascade in Quasi-2D Blue Perovskite Light-Emitting Diodes

Quasi-two-dimensional (2D) perovskites have recently emerged as emitters in blue perovskite light-emitting diodes (PeLEDs). The cascading energy-transfer process between different 2D phases plays an essential role in the high performance of this class of PeLEDs. Herein, we propose an interfacial engineering strategy by incorporating a zwitterionic additive, l-phenylalanine, into the hole-injection layer (HIL), enabling suppression of trap-assisted deactivation channels by virtue of the coordination interactions between the additive and Pb2+ defects in the perovskite phase. In addition, the introduction of l-phenylalanine reduces the release of metallic indium species from indium tin oxide substrates initiated by acidic HILs, resulting in the suppression of luminescence quenching in the perovskite layer. The synergetic benefits create an ideal energy landscape, blocking energy losses and boosting PeLED performance with a peak external quantum efficiency of 10.98% at 480 nm and extended device lifetimes. Our approach provides a versatile strategy to achieve high-performance blue PeLEDs.