Bright Cyan‐Emissive Copper(I)‐Halide Single Crystals for Multi‐Functional Applications

Abstract

In particular, the fluorescence inks could be easily printed on the banknote, ID card, passport, and packaging of the product; accordingly, the anti-counterfeiting technology based on fluorescence tags has been highlighted with low cost, high-security level, and facile decryption process that can be directly recognized by the ultraviolet (UV) lamp. [35] For instance, the emission of A 2 AgX 3 (A = Rb, Cs; X = Cl, Br, I) could be facilely regulated by changing the composition, showing the application potential in fluorescence anti-counterfeiting. [36] Nevertheless, the limited response range makes traditional UV light-activated anti-counterfeiting fluorescence tags unsatisfactory for the requirements of high-level anticounterfeiting applications. Therefore, exploring complicated anti-counterfeiting fluorescent materials whose response range can be broadened from UV to near-infrared (NIR) light and even X-rays are urgently needed. The fluorescent materials with a down-conversion response require a suitable energy gap that the UV light could activate. However, the traditional metal-oxide semiconductors possess a wide bandgap; thus, it is necessary to introduce lanthanide metal ions to act as activators. [37] The up-conversion photoluminescence (UCPL) process usually involves photosensitizers (Yb 3+ , etc.) to absorb infrared light and transfer the absorbed energy to other luminescent species. [38] Nonetheless, the multi-photon absorption process usually occurs under the irradiation of high-power laser (e.g., >1 kW cm −2 ), hampering the application in practical scenarios. Moreover, the doping amount of photosensitizers is critical for the final emissive behaviors and lacks batch-to-batch and labto-lab reproducibility. In terms of X-ray scintillators, except for extraordinary luminescence efficiency, the attenuation capability to X-ray becomes another critical criterion for screening the efficient scintillators, which requires the participation of heavy atoms, such as metal and iodine elements. Overall, it is still challenging to synthesize a single-source material with response to UV, NIR, and X-ray simultaneously.Recently, the outstanding photophysical performance of metal halide perovskites and derivatives has brought them to the research forefront of luminescent materials. For instance, the 3D CsPbX 3 (X = Cl, Br, and I) nanocrystals show extraordinary down-conversion properties due to the spatial confinement of excitons within nanocrystals. [39][40][41] Fortunately, lowering down the crystal structure dimensionality is another strategy Anti-counterfeiting has become a serious issue around the global world; fluorescence-based tags are praised for the low-cost and facile decryption process. However, the high-level anti-counterfeiting application requires incorporating multifunctional luminescent materials with response to different excitation sources. Herein, a dimeric Cu(I)-halide-clusters-assembled singlecrystal (AEP) 2 Cu 2 I 6 •2I•2H 2 O (AEP = N-aminoethylpiperazinium) concerning a high down-conversion photol...

Zero-Dimensional Hybrid Cuprous Halide of [BAPMA]Cu2Br5 as a Highly Efficient Light Emitter and an X-Ray Scintillator

“…[Bmpip] 2 Cu 2 Br 4 (Bmpip = 1-butyl-1-methylpiperidinium) displays broadband yellow light PL/RL emission with a high PLQY of 48.2% and a light yield of 16,000 photons/MeV under excitation of UV light and X-rays, respectively . Similar hybrid cuprous halide-based X-ray scintillators are also reported including [AEP] 2 Cu 2 I 6 ·2I·2H 2 O (55,650 photons/MeV), [Bmpip] 2 CuBrI (25,000 photons/MeV), [TBA] 2 CuCl 2 (24,134 photons/MeV), [DIET] 3 Cu 3 Br 3 (25,000 photons/MeV), etc. ,, …”

Copper Iodide Inks for High-Resolution X-ray Imaging Screens

“…In addition to all-inorganic Cu­(I)-based systems, organic–inorganic hybrid Cu­(I)-based halides, such as (C 8 H 20 N) 2 Cu 2 Br 4 , (Bmpip) 2 Cu 2 Br 4 , and (TBA)­CuX 2 , present exciting radioluminescence (RL) behavior. − However, most of them are synthesized in the single-crystal state; thus, different binding polymers (e.g., PMMA, PDMS, and PSF) are required to prepare effective scintillation screens. Generally, nanocrystals or microcrystals/polymer scintillation screens have several limitations, including poor uniformity, lack of appropriate solvents, and low equivalent density of scintillation materials. ,,, Additionally, poor moisture stability is a primary limitation of inorganic Cu­(I)-based powders, such as Cs 3 Cu 2 I 5 , and severe deliquesce occurs when they are placed in a humid environment …”

“…Generally, nanocrystals or microcrystals/polymer scintillation screens have several limitations, including poor uniformity, lack of appropriate solvents, and low equivalent density of scintillation materials. 27,31,36,40 Additionally, poor moisture stability is a primary limitation of inorganic Cu(I)-based powders, such as Cs 3 Cu 2 I 5 , and severe deliquesce occurs when they are placed in a humid environment. 27 To address these limitations, we successfully synthesized two strongly emissive, ionic-species-based, water-dispersible Cu(I) iodide inks, comprising zero-dimensional (0D) Cu 4 I 6 (L 1 ) 2 (L 1 = 1-propyl-1,4-diazabicyclo[2.2.2]octan-1-ium) and one-dimensional (1D) Cu 4 I 6 (L 2 ) 2 (L 2 = 4-dimethylamino-1-ethylpyridinium), with excellent thermal, moisture, and radiation stabilities.…”

Boosting the Self-Trapped Exciton Emission in Cs2NaYCl6 Double Perovskite Single Crystals and Nanocrystals

“…Halide perovskites have been proposed as promising potential materials for applications in light-emitting devices (LEDs), photodetectors, and X-ray scintillators because of their outstanding optical and electronic properties. − In particular, lead-based halide perovskites exhibit high photoluminescence quantum yields (PLQYs), low-cost synthesis, and large absorption cross sections. − But the toxicity of lead hampers practical commercialization development. To address this key problem, scientists have tried to replace the bivalent lead with other metal elements with low toxicity, such as a bivalent cation (Sn 2+ and Ge 2+ ) or a trivalent cation (In 3+ , Sb 3+ , and Bi 3+ ), etc. − However, the bivalent Sn 2+ and Ge 2+ cations are extremely unstable in ambient conditions, and it is easily oxidized to a tetravalent state .…”