Mixed-halide quasi-two-dimensional blue-emitting perovskite light-emitting diodes based on dual-spacer ligand modulation

Abstract

The development of high-performance blue perovskite light-emitting diodes (PeLEDs) continues to face significant challenges in achieving both spectral stability and device efficiency required for practical applications in full-color displays and solid-state lighting. Herein, we propose a dual-spacer ligand strategy to address these limitations through precise phase distribution control in mixed-halide quasi-two-dimensional (quasi-2D) perovskites. By leveraging the synergistic competition between phenylethylammonium bromide (PEABr) and propylammonium bromide (PABr) ligands, we achieve optimized phase composition with suppressed formation of small-n phases (n ≤ 3) while promoting dominant emission from larger-n phases, thereby minimizing energy funneling losses during interphase energy transfer. The optimized dual-ligand system (1:1 PEABr:PABr ratio) yields blue-emitting PeLEDs demonstrating remarkable performance metrics: stable electroluminescence at 485 nm with a peak external quantum efficiency of 7.3 %, maximum luminance of 755 cd m⁻², and operational lifetime (T₅₀) of 660 s at initial luminance of 100 cd m⁻². This work provides fundamental insights into phase engineering of quasi-2D perovskites while establishing a practical pathway toward spectrally stable mixed-halide blue-emitting PeLEDs.