Preparation of electrochromic Prussian blue nanoparticles dispersible into various solvents for realisation of printed electronics

An insoluble solid of historic Prussian blue (PB) was transformed into dispersible PB nanoparticles in water and various hydrophilic and hydrophobic organic solvents. Via hybrid surface modification using Na4[FeII(CN)6] and short-chain alkylamines, the insoluble PB was successfully dispersed in hydrophilic-and-hydrophobic boundary alcohols, such as n-butanol. The n-butanol-dispersible PB nanoparticles afforded homogeneous spin-coated thin films on various substrates. The chemisorbed shorter-chain alkylamines, n-propylamines, of the PB nanoparticles were thermally released at 100 °C from their surfaces to present stubborn electrochromic PB thin films adhering to the substrate via mutual coordination-bonding networks.