Conductivity TCNQ salt-polymer composites

In the present report, we discuss the relative importance of the matrix effect on the semi-conductivity and the stability of TCNQ salt/polymer composites through the studies of CT interactions and film morphology. 

The film conductivity and the stability of TCNQ salt/polymer composites are strongly dependent on the matrix polymers, more specifically on the electron-donor strength of the p lymers which controls CT interaction with TCNQ salts. With Et,NH (TCNQ), ... 

Electrically Conductive Polymer Composites of 7,7,8,8-Tetracyanoquinodimethane (TCNQ) Salt Dispersion... 

Electrically conductive polymer composites were made by dispersing TCNQ salt in polymer matrices. Composite film conductivity and stability are discussed in terms of charge-transfer interaction between TCNQ salt and matrix polymer and the resulting film morphology. The extent of CT interaction and tendency of microcrystallization of TCNQ salt in the matrices were determined by visible spectra. Conductivity and stability are morphology dependent of the film high conductivity requires a uniform, densely packed dispersion of TCNQ salt microcrystallites. The highest conductivity was always attained at [TCNQ°]/[TCNQ ]sl. 

The most desirable properties for electrically conductive polymeric materials are film-forming ability and thermal and electrical properties. These properties are conveniently attained by chemical modification of polymers such as polycation-7, 7,8, 8-tetracyanoqninodimethane (TCNQ) radical anion salt formation (1-3). However, a major drawback of such a system is the brittle nature of the films and their poor stability (4,5) resulting from the polymeric ionicity. In recent years, polymeric composites (6-8) comprising TCNQ salt dispersions in non-ionic polymer matrices have been found to have better properties. In addition, the range of conductivities desired can be controlled by adjusting the TCNQ salt concentration, and other physical properties can be modified by choosing an appropriate polymer matrix. Thus, the composite systems are expected to have important advantages for use in electronic devices. 

In order for the composites to become conductive, the TCNQ salt, initially dissolved in DMF solution before casting, should subsequently recrystall ze as pure microcrystals. To realize this condition with NMP TCNQ7, two approaches are possible one is to reduce the association through choosing weak donor polymers as matrices, and another is to dope the system with TCNQ so that TCNQ salt association with the polymer should be reduced through a competitive reaction with TCNQ, thereby facilitating salt crystallization. 

---