Tunable Emission in Cu(I)/Mn(II) Codoped 2D Hybrid Cd Chloride Perovskites for White Light‐Emitting Diodes and Anticounterfeiting

Abstract Low‐dimensional halide perovskites have recently attracted considerable attention as promising candidates for single‐component white light‐emitting diodes (WLEDs). However, it remains challenging to achieve highly efficient white light emission in 2D systems. Herein, white light emitting Cu + /Mn 2+ codoped 2D (PPDA)CdCl 4 perovskites are synthesized via a facile fabrication method. The host is weakly emissive. However, Cu + and Mn 2+ doping can lead to strong green and orange‐red emission, respectively. Spectroscopic characterizations show that there are two independent emission centers, the Cu + ‐induced extrinsic self‐trapped exciton (STE), which leads to the green emission, and the isolated Mn 2+ ion which results in orange‐red emission via the inherent 4 T 1 (G)→ 6 A 1 (S) transition. Interestingly, by optimizing the ratio of Cu + and Mn 2+ , the codoped sample can exhibit tunable white light emission with variable correlated color temperatures and high photoluminescence quantum yields of 45.2%–51.1%. In addition, the codoped samples can also exhibit interesting excitation‐dependent emission properties. This work opens up new opportunities for the development of high‐performance 2D perovskite luminescent materials.