?
Non-Conjugated Poly(Diphenylene Phthalide) - New Electroactive Material
In organic electronics, conjugated conductive polymers are most widely used. The scope of
their application is currently very wide. Non-conjugated polymers are used much less in electronics
and are usually used as insulation materials or materials for capacitors. However, the potential of
non-conjugated polymers is much wider, due to the fact that new electronic materials with unique
electronic properties can be created on the basis of non-conjugated polymers, as well as other
inorganic dielectrics. This article demonstrates the possibilities of creating electrically conductive
materials with unique electronic parameters based on non-conjugated polymers. The results of the
study of the sensory properties of humidity are given as examples of the practical application of
the structure. The abnormal electronic properties are realized along the interface of two polymer
dielectrics with functional polar groups. The submicron films of polydiphenylenephthalide were used
as a dielectric. It is shown that a quasi-two-dimensional electronic structure with abnormally large
values of conductivity and mobility of charge carriers occurs along the interface. These structures are
often called quasi-two-dimensional electron gas (Q2DEG). This article describes the manufacturing
processes of multielectrode devices. Polymer films are deposited via the spin-coating method with
polymer solutions in cyclohexanone. The metal electrodes were manufactured through thermal
deposition in a vacuum. Three types of metal electrodes made of aluminum, copper and chromium
were used. The influence of the electron work function of contacting metals on the electronic
parameters of the structure was studied. It was established that the work function decrease leads
to an increase in the conductivity and mobility of charge carriers. The charge carrier parameters
were estimated based on the analysis of the current-voltage characteristics within the space-chargelimited
current technique. The Richardson-Schottky thermionic emission model was used to evaluate
values a potential barrier at metal/organic interfaces. It was established that the change in ambient
humidity strongly affects the electronic transport properties along the polymer/polymer interface.
It is demonstrated that the increase in conductivity with an increase in humidity occurs due to an
increase in the mobility of charge carriers and a decrease in the height of the potential barrier at
the three-dimensional metal contact with two-dimensional polymer interface. The potential barrier
between the electrode and the bulk of the polymer film is significantly higher than between the
electrode and the quasi-two-dimensional polymer structure.