  In this work the effect of an ion gel outer-layer stuck on top of ITO/PBT/Sn
devices was investigated towards its effects on the electrical properties. When
this external electrolyte film is in contact with any top permeable electrode
it produces a self-biasing effect and changes the charge carriers injection
properties. The outer-layer promoted situations where the output current
increases up to two orders of magnitude and others where the output current
decreases one order of magnitude in comparison to the same samples without it.
Admittance spectroscopy measurements were made and the proposed equivalent
circuit model indicates that the interfacial electrical properties dominate
charge injection face to the bulk properties when the outer-layer is present.
All the changes observed here are reversible after the ion gel is detached and
replaced, indicating that ions do not diffuse into the active layer. The
observed results can contribute to improve the current density in certain
sandwich structures as well as notify that electrolyte external films can
behave as an active layer promoting electrical changes into sandwich devices
and can be extended to cases where the electrolyte film is used as substrate.
