Combination of novel fluorinated Ag-In-Zn-S quantum dots with micro/nano-scale hierarchical porous structure for robust luminescent, superhydrophobic surfaces

Counterfeiting is a quite huge threat to our modern society. Anti-counterfeiting technology based on photoluminescent (PL) materials has been considered as a powerful solution to overcome this challenge due to their unique advantages such as facile design, high-level security, and fast authentication. However, most of present PL materials suffer from high-cost, low-stability or toxic. In this work, an environmental-friendly I−III−VI quantum dots (f-Ag-In-Zn-S QDs) was designed and synthesized, which shows similar optical properties with Ag-In-Zn-S QDs without modification. The novel QDs with low-surface energy modification was adopted to prepare stable superhydrophobic and luminescent surfaces combining modified silica (f-SiO₂) by simple spraying method. With varying excitation wavelength from 380 to 500 nm, the PL peak of multifunctional surfaces redshifted from 504 to 587 nm. Correspondingly, orange and red photoluminescence patterns were clearly observed when the ant-counterfeiting coatings were irradiated by UV light with 365 and 395 nm, respectively. Moreover, the intentionally designed similar low surface energy components from the outer of f-Ag-In-Zn-S QDs and f-SiO₂ nanoparticles made them uniformly disperse on the substrate and constructed micro/nano-scale hierarchical porous structure, which provided same superhydrophobic and luminescent properties on the entire surface of dual-functional coating. Furthermore, the superhydrophobicity played a protective role in making sure that the dual-functional coating still can work even they were applied by different harsh treatments including ultrasonic oscillation, sandpaper abrasion, boiling water jet impacting, acid or alkali solution immersion, ultraviolet irradiation, heating/cooling. Therefore, this simple, green and low-cost technology provided a useful example for designing and fabricating stable ant-counterfeiting materials.