Printing and characterizing plasmonic nanoparticles

Printing plasmonic nanoparticles is of interest e.g. in the fields of large area printing for photovoltaic applications, biomedical and photonic sensor developments, as well as for digital printing of security tags for smart packaging and anti-counterfeit applications. We have studied plasmonic gold nanoparticles embedded in printable PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), a transparent hole conducting organic semiconductor material). Aqueous dispersions of chemically stabilized gold nanoparticles (e.g. 40 nm in diameter) were used as plasmonic nanoparticle additives for the nanocomposite coating materials and inks. Inkjet printing and spincoating experiments have been performed on glass substrates. The inkjet printed nanocomposite microstructures and thin film coatings were investigated by true non-contact atomic force microscopy (AFM), 3D profilometry, optical microscopy. Absorbance spectroscopy was used to characterize the gold nanoparticle dispersions upon synthesis and encapsulation in comparison to commercial gold nanoparticles. AFM topography and phase contrast data reveal the domain structure of PEDOT:PSS, and indicate embedding of the nanoparticles within the transparent conducting polymer printed structures. Successive printing of the PEDOT:PSS ink and gold nanoparticle dispersions leads to the contrary to significant topographic contrasts in AFM and optical profilometry. Using the coffee stain effect, we generate inkjet printed plasmonic nanocomposite microstructures that are of potential interest for the application field of smart electrically conducting and plasmonic security tags.