Room‐Temperature Synthesized Cd‐Doped Cs₃Cu₂I₅: Stable and Excitation‐Wavelength Dependent Dual‐Color Emission for Advanced Anti‐Counterfeiting

Abstract

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 Cs3Cu2I5 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 Cs3Cu2I5 changed from deep blue to cold white and finally yellow. Afterwards, Cd‐doped Cs3Cu2I5 was mixed with polystyrene to prepare anti‐counterfeiting ink for silk‐screen printing. Meanwhile, Cd‐doped Cs3Cu2I5 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.

Integrated System Built for Small-Molecule Semiconductors via High-Throughput Approaches

“…In other words, in A31B3 , photons may be emitted from higher-lying excited states, not just the lowest excited state. Most reported EX-De materials are, however, either nanoparticles or metal complexes. − Our material library provides a compelling strategy to construct purely organic dual-emission materials. Of great importance is the fact that all data are obtained under the same conditions.…”

Variable halide perovskites: diversification of anti-counterfeiting applications

“…In 2022, Qu et al synthesized Cs 3 Cu 2 I 5 using a centrifugal method that exhibited two-color emission. 55 This phenomenon originated from the soft 0D structure of Cs 3 Cu 2 I 5 , where a single [CuI 4 ] tetrahedron can be regarded as a luminescence center. When Cd replaces Cu, part of the [CuI 4 ] tetrahedra are transformed into [CdI 4 ] ones, which become new luminescence centers (Fig.…”

Improved Energy Transfer in Mn-Doped Cs3Cu2I5 Microcrystals Induced by Localized Lattice Distortion

“…21,22 For Cs 3 Cu 2 I 5 halides, doping with cations such as Na + , Cd 2+ , and In 3+ has been reported to show improvement of the emission intensity and stability of Cs 3 Cu 2 I 5 microcrystals (MCs). 23,19,24,25 The PL intensity of Na-doped Cs 3 Cu 2 I 5 powder is enhanced by 17.4% compared with the undoped Cs 3 Cu 2 I 5 powder, and the PL thermal stability is improved as well. For Cd-doped Cs 3 Cu 2 I 5 samples, the emission changed with the excitation wavelength, and the intensity could be recovered after 10 heating-and-cooling cycles.…”

“…18 The PL spectrum excited at 310 nm has a broad emission peak centered at 445 nm with a 75 nm fwhm, which is consistent with the previous reports for Cs 3 Cu 2 I 5 MCs and can be assigned to be the STE emission. 24 When the sample is monitored at 445 nm, only the host absorption band at ∼300 mm can be seen. When the monitoring wavelength is 560 nm, the PLE spectrum exhibits three absorption bands at around 310, 378, and 480 nm that can be assigned to the intrinsic absorption of the host and the 6 A 1 → 4 T 2 (D) and 6 A 1 → 4 T 1 (G) transitions of Mn 2+ ions, respectively.…”