The Synthesis And Application Of Multicolor Photoluminescent Silicon Nanocrystalline Anti-counterfeiting Ink

As one of the promising semiconductor materials,silicon nanocrystals have been widely used in solar cells,optoelectronics,medical diagnostics,and biological imaging in the past few decades.Due to their high natural abundance,good biocompatibility and optical size dependence.Based on the research on the preparation of hydrophobic silicon nanoparticles,a method of hydrophilic silicon nanocrystals was gradually discovered,and it has also been applied in certain aspects.However,there are few reports on the application of photoluminescent silicon nanocrystals of different colors together in anti-counterfeiting inks.This thesis uses silicon powder and silane as raw materials to prepare red,green and blue silicon nanocrystalline particles,and mix it with sodium alginate solution to prepare ink,through the"RGB"three-color principle,on cotton fabric and paper multi-color anti-counterfeit pattern printing.In this process,the prepared silicon nanocrystals and the printed substrate were investigated for different properties.First,SiO is used as a silicon source,and a series of processes were used to graft10-undecylenic acid to prepare silicon nanocrystals that were red under ultraviolet light;with3-aminopropyltriethoxysilane?APTES?is a silicon source,which reacts with sodium ascorbate?C₆H₇NaO₆?and tiger red sodium salt(C₂₀H₂Cl₄I₄Na₂O₅)to prepare green and blue silicon nanocrystals under ultraviolet light.The morphology and fluorescence characteristics of the prepared silicon nanocrystals were found to have good crystal forms,high fluorescence stability,and a certain excitation wavelength dependence,which can emit different colors of light under the same ultraviolet light.Proved that anti-counterfeiting with different fluorescent colors can be carried out.Then,the ink is prepared by mixing with different percentages of sodium alginate??C₆H₇NaO₆?x?for printing,and no additional fluorescent agent is needed.The research on the prepared ink found that proper increase of sodium alginate content has better rheological performance and clearer printed pattern texture;research on the printed substrate found that the printed pattern has high firmness,after the eraser and with the tape treatment,the pattern under ultraviolet light is still clearly visible,and it basically does not fade.The research results show that the three kinds of silicon nanocrystals prepared have good fluorescence stability,high luminous intensity,and can be excited at the same time.It is an innovation to prepare three-color silicon nanocrystals into inks for anti-counterfeiting printing with different colors.Moreover,the anti-counterfeit patterns printed with the manufactured ink are clearly visible under ultraviolet light,and the fastness is reliable.This method of preparing blue fluorescent silicon nanocrystals was also discovered for the first time,providing a new direction for preparing silicon nanocrystals.