Optimizing Blue Perovskite LEDs via Dual-Ligand Assisted Quasi-2D Layering

A highly efficient blue quasi-2D perovskite light-emitting diode (PeLED) is developed using a dual-ligand composition in a CsPbBr₃ perovskite film. By incorporating ethane-1,2-diammonium bromide (EDBr₂) and methylphenylammonium chloride (MeCl), it forms isolated 2D perovskite layers and enhances charge transfer between these layers that minimizes nonradiative recombination. The PeLED displays a peak emission that is characteristically blueshifted from ~520 nm for unmodified pristine CsPbBr₃ films to 480 nm for the quasi-2D structured films. The addition of EDBr₂ stabilizes the perovskite structure, leading to better energy alignment, reducing defects and enhances the formation of Dion-Jacobson phases as evidenced by UV-Vis absorption, photoluminescence, and electroluminescence characterization studies. Comprehensive analyses show that this method is pivotal in achieving both high efficiency and long-term operational stability for blue PeLEDs.