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2 Materials Science Poland

2 2009

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Electronic and gas sensing properties of soluble phthalocyanines

Pochekailov S., Rais D., Nešpůrek S., Rakušan J., Karásková M.

Materials Science Poland

2009

Vol. 27, No. 3

781--795

Some optical and electrical properties of 3-diethylamino-1-propylsulfonamide substituted zinc and metal-free phthalocyanines are presented. These materials are sensitive to NO2 even at concentrations as low as 0.1-2.5 ppm. Electrical conductivity and photoconductivity were used as the detection methods.

Electrical conductivity in thin films fabricated from nanoparticles of a polymeric composite based on PEDOT

Rais D., Hain J., Pich A., Pochekailov S., Nešpůrek S., Adler H. J. P., Hamáček A., Řeboun J.

Materials Science Poland

2009

Vol. 27, No. 3

769--780

A comparative study of electrical properties of films fabricated from a series of polymeric core shell particles and microgels is presented. The core shell particles consist of spherical polystyrene core covered by electrically conductive poly[3,4-(ethylenedioxy)thiophene] (PEDOT). Microgels are composed of PEDOT grains embedded into crosslinked, electrically insulating polymer bodies. The electrical resistivity of the films changes from 12 G?ˇcm to 100 ?ˇcm; the value depends on the thickness of the shell cover and the type of oxidant used for PEDOT polymerization. Electrical conductivity in the films of core shell particles is thermally activated and obeys the inverse Meyer-Neldel rule, which indicates that the electrical conductivity is governed by a common transport mechanism. Electrical conductivity depends, among others, on the humidity in the surrounding environment. In films consisting of particles with a high PEDOT content (and thus high conductivity) the resistivity increases as the humidity increases. Conversely, when the films are formed from particles having a low PEDOT content, the humidity has a reverse effect. An explanation for this behaviour is proposed. The frequency dependences of ac conductivities of high conductivity "core shell" and "microgel" films suggest existence of hopping charge carrier transport mechanism for large humidity scale.