A simple formula
For the hybrid ink, the scientists coated gold (which they also used in thismethod) or silver nano-particles with organic, conductive polymers and suspended it in a mix of alcohol and water. After “writing” with this ink on paper, the suspension dries without further processing and eventually builds electronic caps.
Basically the organic compounds have three functions: On the one hand they are ligands, which help to keep the nano-particles suspended in the liquid compound. If the particles would clump together, it would hinder the “printing” of the super caps. Secondly they keep the nano-particles in line and are responsible for their correct arrangement. Because these caps have to be flexible, there has to be a mechanism that moves the particles, but does not break them. This is the third task of the organic compounds. They serve as hinges who guarantee the conductivity. Tobias Kraus, head of the research group at INM, describes the advantages of this process: “The combination with the metal nano-particles is perfect because we can unite mechanic flexibility with the robustness of a metal and additionally increase the electric conductivity.”

Hybrid inks with metal nano-particles 2.0
“Today metal nano-particle inks with ligands are already used in printed electronics”, says Kraus. For example, when OLED displays are printed on flexible substrates. Until now, the polymer-wrappers had to be removed because they are not conductive. This is of great importance because temperature-sensitive materials such as polymer foils or paper would be damaged, when removing the wrapper. According to Tobias Kraus the new hybrid-ink is fully conductive shortly after being printed and mechanically flexible.

What do you think of printed super caps? Where could they come into play? Leave a comment below!