Exciton Trapping and Cascade Energy Transfer Enable Highly Efficient Near-Infrared Electroluminescence in Rare Earth Based Perovskite

Lead-free rare-earth-based halide perovskite have emerged as a promising candidate for near-infrared light-emitting diodes (NIR-LED), yet their development has been hindered by inefficient energy transfer and severe non-radiative losses. Here, we report a comprehensive optimization strategy for Cs 3 YbBr 6 :Er 3+ nanocrystals through Sb 3+ sensitization and niacin passivation, achieving record-breaking electroluminescence performance. Systematic investigations reveal that Yb 3+ serves as a critical energy transfer bridge, with optimal 5% Er 3+ doping yielding a PLQY of 20.34% at 1540 nm. The introduction of Sb 3+ as an efficient sensitizer captures free exciton and enhances energy transfer, boosting the 1540 nm PLQY to 36.6%. First-principles calculations demonstrate that Sb 3+ incorporation reduces the bandgap and promotes charge localization around [SbBr 6 ] 3− octahedra. Furthermore, niacin molecules selectively passivate undercoordinated Yb 3+ sites via carboxyl coordination, reducing film roughness, decreasing trap densities, and achieving balanced carrier mobilities. The resulting LED exhibits multi-wavelength emissions, peaking at 470 nm, 980 and 1540 nm, respectively. It demonstrates an external quantum efficiency of 9.96% and exceptional operational stability of 753 min (T 50 ), representing the highest efficiency reported for various rare-earth-based perovskite LEDs. A practical infrared imaging system is successfully demonstrated, highlighting the potential of this materials platform for next-generation optoelectronic applications.