Dual‐Wavelength Responsive Broad Range Multicolor Upconversion Luminescence for High‐Capacity Photonic Barcodes

Abstract Realizing multicolor emissions of upconversion (UC) luminescence materials is of significant importance for information security and anticounterfeiting fields. Herein, a strategy is reported to achieve UC multicolor luminescence through manipulating the electronic transition process under dual‐wavelength excitation. The novel color can be produced via exploiting the synergistic effect of photons under dual‐wavelength excitation to control electron distribution, and can be further modulated by finely adjusting the excitation power. Furthermore, the range of color‐tunable emissions is expanded by adjusting Yb 3+ ions concentrations due to the energy back transfer (EBT) process. Inspired by this, the materials with broad‐range UC multicolor emissions can be used to design high‐capacity photonic barcodes for anticounterfeiting applications, which provides a significant step for advanced anticounterfeiting of high level security.