Small-Sized CsPbI₃ Quantum Dots for High-Performance Pure Red Light-Emitting Diodes

Small-sized CsPbI3 quantum dots (QDs) are highly promising for fabricating stable pure-red (630–640 nm) light-emitting diodes (LEDs), effectively avoiding the halide segregation issues commonly observed in mixed-halide perovskite nanocrystals. However, synthesizing stable, small-sized colloidal CsPbI3 QDs for high-efficiency LED fabrication remains a significant challenge. In this study, a combined strategy of metal ion doping and ligand engineering was employed to synthesize small colloidal CsPbI3 QDs (approximately 5 nm) with pure red emission (630 nm) using the hot injection method. Combined with post-treatment using n-butylammonium iodide (TBAI), the Zn2+-doped CsPbI3 QDs achieved a photoluminescence quantum yield (PLQY) as high as 94% and demonstrated excellent stability, retaining 92% of their initial PL intensity after 80 days of exposure in air. The LED devices fabricated with the obtained CsPbI3 QDs as emitter layers demonstrated bright electroluminescence at 636 nm with the highest external quantum efficiency value of 10.3%. Furthermore, Zn2+-doped CsPbI3 QDs LEDs also exhibited good operational stability with a half-life of 77 min.