Bulk‐Size and Highly Transparent Composite Phosphor for NIR Spectroscopy

Abstract Near‐infrared (NIR) phosphors offer a novel luminescent solution for NIR spectroscopy, but their efficiency remains low. Herein, it is demonstrated that the high transparency of a phosphor improves its external quantum efficiency by developing a new inorganic–organic composite phosphor. The new bulk‐size and highly transparent composite phosphor is fabricated through layer‐by‐layer assembly of micron‐sized hexagonal LiSrAlF 6 :Cr 3+ powder phosphor. The inline transparency of the final bulk phosphor can be controlled from 0% to 90.2% at a large solid concentration of ≈47 vol.%. With high transparency, the new bulk phosphor allows the phosphor‐conversion light‐emitting diode (pc‐LED) a 2.9 times improvement in efficiency. This paper inspires a feasible and low energy consumption method to facilitate next‐generation NIR pc‐LED phosphors.