On the mechanism of electrical conduction in plasma-polymerised thiophene thin films

Abstract

High-field dark conduction in (DC discharged) plasma-polymerised thiophene thin films is reported. A contact-limited Schottky mechanism is found to predominate at fields above 3*105 V cm-1. The dominance of the Schottky mechanism is confirmed by employing dissimilar-electrode configurations. The metal-polymer interface barrier heights calculated are 1.22 eV for Al, 1.03 eV for Cu and 0.879 eV for Au.

Optical and electrical characterization of plasma polymerized pyrrole films

“…In general, such a plot with a slope equal to or larger than 2 suggests the possibility of SCLC. 42,43 However, in the present case, the value of the slope is much smaller than that required for SCLC. Another method to check for the possibility of SCLC is to plot ln J against ln d. For SCLC, the thickness dependence of the current density is expressed by Jϰd Ϫt , where t is a parameter depending upon the trap distribution and ideally is equal to 3.…”

“…Consequently, a general expression of the form JϭJ 0 exp͓͑␤F 1/2 Ϫ ͒/kT͔ ͑6͒ holds equally well for both Schottky and Poole-Frenkel mechanisms, 42,46 where J is the current density at a biased voltage. By taking natural logarithms of Eq.…”

“…42,43,46 A comparison of the experimentally obtained ␤ coefficients values with theoretical values is the easiest method to differentiate between Schottky and Poole-Frenkel mechanisms. 42,43,46 The experimental value of the ␤ coefficient can be obtained from the plot of ln J versus V 1/2 . 42,43,46 Figure 11 depicts such plots for the film with a thickness of 2000 Å.…”

Plasma Deposition of Thiophene Derivatives Under Atmospheric Pressure

“…If the substrate is conductive, this problem can be solved by using electropolymerization with deposition directly on the substrate. Nevertheless, both chemical and electrochemical synthesis, are Plasma polymerizations of thiophene and derivatives at low pressure have already been reported [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] . However, since this technique requires a high vacuum, it can only be done in a batch process.…”

Designing of Nano Composites of Conducting Polymers for EMI Shielding

“…However, number of methods such as photochemical polymerization [71], pyrolysis [72,73], metal-catalyzed polymerization [74][75][76], solid-state polymerization [77], plasma polymerization [78], ringforming condensation [79], step-growth polymerization [80,81], and soluble precursor polymer preparation [82,83], have been reported in literature for synthesis of conjugated polymers. Here only chemical and electrochemical polymerization are described briefly.…”