Sacrificial ligand route to hybrid polythiophene–silver nanoparticles for sinter-free conductive inks

We report the synthesis of AgNP@PEDOT:PSS hybrid conductive particles with silver cores and polythiophene shells that can be used to formulate sinter-free inks for printing electronics. First, Ag nanocrystals capped with the weakly bound ligand aminohexanoic acid (ε-Ahx) are prepared. The ligand shell is exchanged by reacting the dispersion with the polymer ionomer mixture poly(3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS). The particles are characterized by electron microscopy, dynamic light scattering, Z potential, and Raman spectroscopy, confirming the replacement of the ligands on the metal particle surface. The resulting dispersion is colloidally stable as confirmed by DLS. Inks with a solid content of the hybrid particles of 300 mg mL−1 were prepared and deposited on different substrates. The new particles are components for hybrid inks that become electrically conductive without any chemical or thermal post-deposition treatment. We show that silver-based hybrid inks can be deposited on different substrates and possess an average conductivity after 24 h of drying at room temperature of 1.726 × 106 S m−1 ± 0.326 × 106 S m−1, only one order of magnitude lower than elemental silver and within the same order of magnitude as their gold ink counterpart.