Mn and Cu codoped Cs₂ZnBr₄metal halide with multiexcitonic emission toward anti-counterfeiting

The growing demand for optical anti-counterfeiting technology requires the development of new environmentally-friendly smart materials with single-component, multimodal fluorescence. Herein, Cs₂ZnBr₄:0.3Mn²⁺&0.15Cu⁺, as an efficient multimodal luminescent material with excitation-wavelength-dependent emission is reported. Under 365 nm and 254 nm UV light excitation, Cs₂ZnBr₄:Mn²⁺&Cu⁺emits mutually independent green light at 525 nm and blue light at 470 nm, which origin from the emission of Mn²⁺and the Cu⁺enhanced self-trapped excitons of Cs₂ZnBr₄, respectively. Furthermore, the multiexcitonic emission is applied to anti-counterfeiting applications and information encryption and decryption engineering. This codoped strategy provides a colorful step to expand the new metal halide materials in fluorescent anti-counterfeiting and information encryption and decryption.