Mn and Cu codoped Cs 2 ZnBr 4 metal 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, Cs 2 ZnBr 4 :0.3Mn 2+ &0.15Cu + , as an efficient multimodal luminescent material with excitation-wavelength-dependent emission is reported. Under 365 nm and 254 nm UV light excitation, Cs 2 ZnBr 4 :Mn 2+ &Cu + emits mutually independent green light at 525 nm and blue light at 470 nm, which origin from the emission of Mn 2+ and the Cu + enhanced self-trapped excitons of Cs 2 ZnBr 4 , 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.