Ultrabroadband (Vis-NIR) Emission in Single-Component Perovskite LEDs via Tailored Multi-Exciton Energy Transfer Pathways

The development of ultrabroadband light sources spanning the visible (Vis) to near-infrared (NIR) range is of fundamental importance for cutting-edge applications in communication, metrology, and quantum technologies. Although phosphor-converted LEDs have extended emission, they still suffer from spectral gaps, inadequate color rendering, and constrained NIR output. Here, a promising approach is introduced by tailoring multi-exciton energy transfer pathways to realize ultrabroadband Vis-to-NIR emission in Sb 3 ⁺/Ln 3 ⁺ co-doped vacancy-ordered Cs₂HfCl₆ perovskite nanocrystals. By systematically optimizing Sb 3 ⁺ and Ln 3 ⁺ doping concentrations, excitation wavelengths, and lanthanide ion selection, the energy transfer pathways between singlet and triplet self-trapped exciton (STE) states and lanthanide energy levels are modulated. This design facilitates broad spectral tunability through energy distribution control among emission centers, improves radiative efficiency by reducing energy losses during transfer processes, and promotes stable performance by mitigating excessive energy accumulation. The resulting single-component LED based on Sb 3 ⁺/Pr 3 ⁺ co-doped NCs delivers broadband emission extending to ≈1200 nm, high spectral quality (CRI ∼ 98.1, R9 ∼ 98), strong visible/NIR PLQY (≈80%), and steady operation over 50 h. The findings provide insight into energy transfer engineering in low-dimensional perovskites and offer a viable route toward emerging ultrabroadband solid-state light sources.