Reversible Transformation between Cs<sub>3</sub>Cu<sub>2</sub>I<sub>5</sub> and CsCu<sub>2</sub>I<sub>3</sub> Perovskite Derivatives and Its Anticounterfeiting Application
Xiangtong Zhang, Biao Zhou, Xueping Chen, William W. Yu
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.