Efficient Near‐Infrared Emission from W ⁴⁺ in Cs ₄ MnBi ₂ Cl ₁₂ Quadruple Perovskite via “Mn ²⁺ Energy Bridge”

ABSTRACT Despite the growing demand for near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) in night‐vision and non‐destructive detection technologies, the development of highly efficient NIR‐emitting metal halides remains a significant challenge, primarily constrained by limitation in luminescent efficiency. To address this challenge, we propose a novel strategy employing Mn 2+ as an energy bridge to sensitize W 4+ within the Cs 4 MnBi 2 Cl 12 quadruple perovskite. Through comprehensive structural and photoluminescent characterization, we demonstrate that the incorporation of Mn 2+ creates an effective energy transfer pathway. This pathway enables intense NIR emission from W 4+ at ∼910 nm, covering the spectral range from 800 to 1300 nm with a full width at half maximum (FWHM) of 181 nm. The optimized Cs 4 MnBi 2 Cl 12 :W 4+ achieves a NIR internal quantum efficiency (IQE) of 69% at room temperature (298 K), significantly outperforming most existing NIR‐emitting metal halides. Experimental evidence confirms the energy transfer sequence of [BiCl 6 ] 3− → [MnCl 6 ] 4− → [WCl 6 ] 2− , establishing the Mn 2+ energy bridge and achieving a maximum energy transfer efficiency of up to 78%. This work not only provides a promising candidate material for high‐performance NIR pc‐LEDs, but also proposes a novel strategy for designing efficient NIR‐emitting metal halides.