The effect of plasma treatment on the permeability of PET substrates

摘要

Poly ethylene terephthalate (PET) is a favorite polymer for applications in flexible electronics such as flexible displays and solar cells. Also it has extensive applications in food and packaging industries. Despite its good optical and mechanical properties it suffers from gas permeability through it [1–2]. This is a critical drawback for applications in flexible electronics and especially for organic displays. A considerable decrease in permeability of polyethylene terephthalate (PET) films by means of surface plasma treatment in a reactive ion etching system is reported. The effects of hydrogen, oxygen and SF6 radio frequency plasma on the surface properties of PET polymers are investigated by SEM, AFM and X-ray photon spectroscopy (XPS) and optical spectroscopy. Also the penetration of air through the treated substrates was investigated using a vacuum test. The creation of new C-O bonds and C-F bonds are believed to be improving the physical properties of the substrate without significantly degrading its optical behavior. It is found that hydrogen and oxygen plasmas lead to about two-fold and four-fold reduction in the penetration of air through the PET films, respectively.