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

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⁺/Mn²⁺ codoped 2D (PPDA)CdCl₄ perovskites are synthesized via a facile fabrication method. The host is weakly emissive. However, Cu⁺ and Mn²⁺ 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 Mn²⁺ ion which results in orange-red emission via the inherent ⁴T₁(G)→⁶A₁(S) transition. Interestingly, by optimizing the ratio of Cu⁺ and Mn²⁺, 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.