Reversible Transformation between Cs₃Cu₂I₅ and CsCu₂I₃ Perovskite Derivatives and Its Anticounterfeiting Application

Abstract

Lead halide perovskites have promising values in photoelectronic and photovoltaic applications, but the toxicity of lead is a hard barrier. Copper halide perovskite derivatives (CHPDs), as a lead-free substitution of lead halide perovskites, also exhibit excellent photoelectric properties. Here, we present a facile one-step route for the synthesis of blue-emissive Cs3Cu2I5 (emission at 440 nm) and yellow-emissive CsCu2I3 (emission at 552 nm) CHPDs in ethanol at room temperature. Triggered by ethanol or CsI, a reversible chemical transformation accompanied by emissive color change between Cs3Cu2I5 and CsCu2I3 CHPDs was achieved. The reversible transformation mechanism was discussed, and this transformation was employed for effective anticounterfeiting.

Unraveling the Phase Transition and Luminescence Tuning of Pb-Free Cs–Cu–I Perovskites Enabled by Reaction Temperature and Polar Solvent

“…To date, different synthetic approaches have been developed to prepare Cs–Cu–I perovskites, such as colloidal chemical methods, antisolvent strategy, and mechanical grinding methods . The rapid progress made in the synthesis of Cs–Cu–I perovskites drove the development of their applications in light-emitting diodes, photodetectors, anticounterfeiting, and so on. − For example, researchers demonstrated that the reversible conversion between blue-emitting Cs 3 Cu 2 I 5 and yellow-emitting CsCu 2 I 3 through exposing or removing water exhibited excellent stability in the anticounterfeiting applications. , Yet, to date, few works have been reported on the relationship between luminescence tuning and phase transition of Cs–Cu–I perovskites on the nanoscale.…”

“…27−31 For example, researchers demonstrated that the reversible conversion between blue-emitting Cs 3 Cu 2 I 5 and yellow-emitting CsCu 2 I 3 through exposing or removing water exhibited excellent stability in the anticounterfeiting applications. 32,33 Yet, to date, few works have been reported on the relationship between luminescence tuning and phase transition of Cs−Cu−I perovskites on the nanoscale.…”

Lead-free Inorganic Perovskite Cs-Cu-I Embedded Waterproof Nanofiber Films for White Color Emission

“…S2(a)). Generally, CsI is dissolved from Cs 3 Cu 2 I 5 in the presence of moisture due to the high solubility of CsI in water, which leads to the formation of yellow-emissive CsCu 2 I 3 product within several minutes [10,23]. However, the encapsulated Cs 3 Cu 2 I 5 within PS bers can effectively prevent the extraction of CsI and maintain long-term stability by protecting water e ciently.…”

“…To address this issue, it is necessary to develop high stability, eco-friendly broadband emission materials. Recently, many types of lead-free perovskites have been studied to replace toxic metallic lead with other non-toxic metals, such as tin halide (CsSnBr 3 , Cs 4 SnBr 6 ) [6, 7], bismuth halide (Cs 3 Bi 2 Br 9 ) [8], indium halide (Cs 2 InBr 5 ) [9], and copper halide (Cs 3 Cu 2 I 5 , CsCu 2 I 3 ) [10,11] based perovskites.…”

“…Cesium copper halide perovskites (Cs-Cu-X) are representative light emitting materials that are low cost, earth abundant, and provide eco-friendly broadband emission. Synthesis of Cs-Cu-X compounds has been accomplished using solvent evaporation [12], mechanochemical reaction [11,13], QDs in surfactants [14,15], melt growth [16], and vapor co-deposition [17,18], which could be used in optoelectronic applications such as anti-counterfeiting [10,19], polarization [20], and white light-emitting devices (WLEDs) [21,22]. Despite the various advantages and applications mentioned above, Cs 3 Cu 2 I 5 perovskite has low stability in moisture, causing transformation into CsCu 2 I 3 and weak PL intensity [10,23].…”