General inks are composed of four components: functional element, binder, solvent, and additive. Functional inks are inks consisting of an electrically functional element. The three classes of functional inks necessary toward printed electronics are (1) semiconducting, (2) conducting and (3) dielectrics.
- Semiconducting inks are composed of semiconducting organic polymers in solvents, inorganic nanoparticles (Group III-V, II-VI and IV semiconductors and carbon nanotubes) suspended in carrier fluids, or organic-inorganic blends.
- Conductive inks are composed of conductive organic polymers in solvents, metallic particles suspended in binders or organic-metallic blends
- Dielectric inks are composed of organic polymers in solvents, organic polymer thermosets or ceramic-filled organic polymers
Nowadays, polymeric materials exhibiting electrical conductivity are very promising for applications in low-cost and disposable electronics. The field of conducting and semiconducting (conjugated) polymers have a unique set of properties, combining the electronic properties of metals and semiconductors with the processing advantages and mechanical properties of polymers. In addition, some polymeric materials can be solution processable, which makes the implementation of existing printing technologies to printed electronics manufacture possible. Among others, the properties rheology and performance of poly(3,4-ethylenedioxy-thiophene)-poly(styrene sulfonate) (PEDOT: PSS) and poly(3-hexyl thiophene) based inks are studied and optimized for deposition by different printing methods.