S2. Additional optical images of the obtained MAPbBr₃ NCs@Pb-ZIF patterns on paper under UV excitation

S5. Thermogravimetric curve of the obtained Pb-ZIF powders

S4. (a) UV-Vis absorption spectra of the printed Pb-ZIF and MAPbBr₃ NCs@Pb-ZIF patterns, (b) steady-state PL spectra and (c) PL decay kinetics of the printed MAPbBr₃ NCs@Pb-ZIF patterns

1. Schematic diagram of in-situ growth of MAPbBr₃ NCs from Pb-ZIF framework and optical images of Pb-ZIF (left under ambient light), and MAPbBr₃ NCs@Pb-ZIF (right under UV light)

S1. X-ray diffraction patterns of Pb-ZIF and MAPbBr₃ NCs@Pb-ZIF powders The ideal diffraction peaks of MAPbBr₃ were presented as red vertical line

S3. Enlarged SEM images and corresponding Br and Pb mappings of the commercial paper with MAPbBr₃ NCs@Pb-ZIF NCs

2. (a) TEM image and (b) SAED pattern of Pb-ZIF powders SEM images of (c, d) Pb-ZIF and (e) MAPbBr₃ NCs@Pb-ZIF powders, and (f) Elemental mappings of MAPbBr₃ NCs@Pb-ZIF powder

3. XPS spectra of Pb-ZIF and MAPbBr₃ NCs@Pb-ZIF samples (a) Survey XPS spectra; (b) Pb4f XPS spectra (The offset of Pb 4f peaks marked by an arrow); (c) Br3d XPS spectra of Pb-ZIF and MAPbBr₃ NCs@Pb-ZIF samples; (d) Br3d XPS spectrum of MAPbBr₃ NCs@Pb-ZIF sample after etching

4. (a) Absorption and (b) steady-state PL spectra of Pb-ZIF and MAPbBr₃ NCs@Pb-ZIF samples; (c) PL decay kinetics of MAPbBr₃ NCs@Pb-ZIF sample; (d) Schematic confidential information encryption and decryption process based on Pb-ZIF and MAPbBr₃ NCs@Pb-ZIF; (e) Optical images of the printed Pb-ZIF and MAPbBr₃ NCs@Pb-ZIF patterns under UV excitation

5. SEM images of (a) pristine commercial paper, (b) commercial paper after printed with Pb-ZIF ink, (c) commercial paper with MAPbBr₃ NCs@Pb-ZIF NCs, (d) representative information encryption and decryption procedure, and (e) PL intensity of the printed MAPbBr₃ NCs@Pb-ZIF patterns in the five cycles of encryption and decryption measurement