Small-SizedCsPbI₃ Quantum Dots for High-PerformancePure 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 <i>n</i>-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.