Mn(II)-Doped Two-Dimensional Cd Chloride Perovskites with Near-Unity Orange Emission for White Light-Emitting Diodes

Low-dimensional metal halide perovskites have emerged as a promising class of high-performance phosphors for solid-state lighting applications, owing to their outstanding optical properties, structural diversity, and low-cost solution processability. Here, we report a Mn²⁺-doped two-dimensional (2D) cadmium chloride perovskite, Mn²⁺:(EDA)CdCl₄ (EDA: ethylenediamine), that achieves highly efficient orange light emission with a near-unity photoluminescence quantum yield (PLQY). The host (EDA)CdCl₄ can emit an unusual ultraviolet emission at 320 nm with a PLQY of 51%, associated with Cd vacancy defects. Upon incorporation of Mn ions into the host lattice, an intense broad orange emission emerges at 610 nm with a PLQY of 97% at 265 nm excitation, originating from the spin-forbidden ⁴T₁(G) → ⁶A₁(S) transition of isolated Mn ions. Theoretical calculations and spectroscopic characterizations reveal that efficient electron transfer from the host to Mn contributes to the highly efficient orange emission, giving the doped samples great potential in WLED applications.