Achieving Improved Buried Interface Enabled by Oriented Bridging Molecules in Near-Infrared Perovskite Light-Emitting Diodes

Metal halide perovskites exhibit great promise for applications in solid-state lighting and flat-panel display technologies. Despite significant progress, the current strategies for achieving high-performance perovskite light-emitting diodes (PeLEDs) are largely confined to additive engineering and upper interface modifications, with little attention paid to the buried interface, which plays a crucial role in perovskite crystal growth and charge transport. Here, we demonstrate a novel buried interface modification strategy by substituting polyethylenimine ethoxylated (PEIE) with phosphorylethanolamine (PEA). PEA functions as a bridging molecule between ZnO and perovskite, with its phosphate group anchoring on ZnO and its amino group serving as the nucleation site for perovskite as well as passivating perovskite defects. Furthermore, PEA also passivates the surface defects of ZnO and modulates its energy levels, thereby enhancing electron injection. The resultant PeLEDs exhibit a peak EQE of up to 22.3% with reduced efficiency roll-off and prolonged half-lifetime, which is superior to that of conventional PeLEDs at a peak wavelength of 798 nm.