Mn2+ as an “Optical Energy Shutter” to Regulate Red‐to‐NIR Luminescence in Rare Earth Doped Layered Quadruple Perovskites

Abstract Metal halide perovskites (MHPs) have shown great application prospects in the field of optoelectronics owing to their superior optical and optoelectronic properties. Bandgap engineering and impurity doping are effective ways to achieve regulation of luminous properties in the visible light region. However, realizing efficient deep red and wide‐range tunable near‐infrared (NIR) emission remains a challenge. Here, a series of rare earth (RE 3+ ) ions (RE = Nd, Dy, Ho, Er, Tm, Yb) doped Cs 4 Cd 1− x Mn x Sb 2 Cl 12 (0 ≤ x ≤ 1) quadruple perovskites are designed. An efficient tunable luminescence from red to NIR light is achieved based on the energy transfer (ET) from Mn 2+ to RE 3+ by building the Mn 2+ energy bridge, which covers the NIR‐I (650–900 nm) and NIR‐II (900–1700 nm) regions. Moreover, the ET efficiency is availably influenced by the doping concentration of Mn 2+ . Interestingly, the energy bridge from Mn 2+ to RE 3+ is cut off because of the increased bandgap when Bi 3+ is introduced into the RE 3+ ‐doped Cs 4 Cd 0.4 Mn 0.6 Sb 2− y Bi y Cl 12 (0 ≤ y ≤ 2) lattice. Through bandgap engineering, the ET from Mn 2+ to RE 3+ resembles an “optical energy shutter” which quenches the NIR emission of RE 3+ owing to the mismatched energy level but enhances the emission of Mn 2+ .