Effect Of Dielectric Barrier Research Articles

Effect of dielectric barrier on rectification, injection and transport properties of printed organic diodes

Rectification ratios of 105 were observed in printed organic copper/polytriarylamine (PTAA)/silver diodes with a thin insulating barrier layer at the copper/PTAA interface. To clarify the origin of the high rectification ratio in the diodes, the injection, transport and structure of the diodes with two different copper cathodes were examined using impedance spectroscopy and x-ray photoelectron spectroscopy (XPS). The impedance data confirm that the difference in diode performance arises from the copper/PTAA interface. The XPS measurements show that the copper surface in both diode structures is covered by a layer of Cu2O topped by an organic layer. The organic layer is thicker on one of the surfaces, which results in lower reverse currents and higher rectification ratios in the printed diodes. We suggest a model where a dipole at the dual insulating layer induces a shift in the semiconductor energy levels explaining the difference between the diodes with different cathodes.

The barrier effect in dielectrics: the role of interfaces in the breakdown of inhomogeneous dielectrics

The barrier effect in high voltage engineering is usually understood to mean an increase in the breakdown voltage of the insulation gap due to the use of additional insulation layer (a barrier) which is placed between two layers of the main dielectric. This effect has been known for more than 70 years and it is widely applied in high voltage engineering with a needle-plane configuration to increase the breakdown voltage. The noticeable progress in the barrier effect study was achieved over the last 15 years, when applying new composite polymeric materials with specific properties, the so-called nanomaterials, as the barrier materials. An analysis of existing models of the barrier effect is presented. The influences of various factors such as the barrier position in the gap, the ratio of permittivities and conductivities of the barrier and main dielectric, space charge and inhomogeneous polarization are demonstrated in this review.

The role of polarization in the breakdownof an air gap with barrier

It is shown that the inhomogeneous polarization of an insulation gapwith barrier in an electrical field due to a sharp change in the permittivityand/or conductivity at the interface of `basic dielectric-barrier' is one ofpossible reasons of the so-called barrier effect in dielectrics. The influenceof the preliminary polarization of thin polyethylene terephthalate barriers onthe breakdown voltage of an air gap with a needle-plane configuration underac and dc voltage is determined.