Room-Temperature Synthesized Cd-Doped Cs 3 Cu 2 I 5 : Stable and Excitation-Wavelength Dependent Dual-Color Emission for Advanced Anti-Counterfeiting.

With the development of intellectual properties, concern about advanced anti-counterfeiting is accumulating, which conventional single-modal luminescence can no longer satisfy. As one of rapidly developing 0D materials, copper-based perovskite shows great potential to realize multiple luminescent centers for complex emissions. In this work, Cd was doped into Cs 3 Cu 2 I 5 and showed resultant emission at 560 nm which surprisingly showed a red-shifted excitation peak from that of intrinsic self-trapped emission, resulting in excitation-wavelength dependent emission. When the excitation wavelength increased from 290 nm to 330 nm, the emission of Cd-doped Cs 3 Cu 2 I 5 changed from deep blue to cold white and finally yellow. Afterwards, Cd-doped Cs 3 Cu 2 I 5 was mixed with polystyrene to prepare anti-counterfeiting ink for silk-screen printing. Meanwhile, Cd-doped Cs 3 Cu 2 I 5 maintains outstanding stability after doping, no matter under ambient, continuous UV radiation or high-temperature environment. The intensity can be almost totally recovered after heating-and-cooling cycles. This study lays groundwork for future research into multiple luminescent center manipulation in 0D materials.