Energy Funnel‐Driven Quantum Cutting in Yb 3+ /Er 3+ ‐Doped Quasi‐2D Perovskites Enables High‐Efficiency Dual‐Band Near‐Infrared Light‐Emitting Diodes

Abstract Quasi‐two‐dimensional (quasi‐2D) perovskites exhibit efficient visible‐light emission, but have remained challenging for near‐infrared (NIR) electroluminescence. Here, a breakthrough is reported in achieving NIR emissions at 986 and 1540 nm through quantum cutting in ytterbium/erbium (Yb 3+ /Er 3+ )‐doped quasi‐2D perovskite films. Atomic‐scale transmission electron microscopy reveals that Yb 3+ ions substitute Pb 2+ sites, establishing robust halide coordination that stabilizes the lattice and enables efficient energy transfer. The synergistic combination of Yb 3+ doping and phosphatidylethanolamine (PE) modulates perovskite domain phase distribution, driving the photoluminescence quantum yield (PLQY) to an exceptional 170%—a notable enhancement for NIR emitters. Transient absorption spectroscopy uncovers a cascaded energy transfer mechanism: photoexcited carriers in low‐n‐phases funnel into the n = ∞ phase, enabling sequential energy transfer to Yb 3+ ions and subsequent NIR emission. NIR light‐emitting diodes are fabricated with record‐high external quantum efficiencies (EQEs) of 9.32% at 986 nm and 1.96% at 1540 nm. This work provides atomic‐scale insights into lanthanide ion integration in perovskites and establishes a universal strategy for quantum‐cutting sensitization in optoelectronic materials, paving the way for next‐generation NIR optoelectronic technologies.