Fig. 4: Three-dimensional encrypting application by utilization of Ho–Ce nanoparticles and Yb–Er nanoparticles. | Nature Communications

Fig. 4: Three-dimensional encrypting application by utilization of Ho–Ce nanoparticles and Yb–Er nanoparticles.

From: Excitation energy mediated cross-relaxation for tunable upconversion luminescence from a single lanthanide ion

Fig. 4

a The design principle of the three-dimensional encryption. UCNP A is the nanoparticle NaYF4:Yb/Ho/Ce@NaYF4:Yb@NaNdF4:Yb. UCNP B is the nanoparticle NaYbF4:Er@NaYF4:Yb(90%)@NaNdF4:Yb. b Luminescent pattern variations upon different three-dimensional excitation parameters. Scale bar is 1 cm. c Experimental demonstration of three-dimensional decryption of luminescent QR code by using these luminescence variable UCNPs. Scale bar is 1 cm.

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