Impact of Silver Nanoparticle Embedment on the Frequency Dispersion and Dielectric Relaxation in Dodecylbenzenesulfonic Acid Doped Polyaniline
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Among this new generation of intrinsically conducting polymers, polyaniline (PANI) is one of the most hopeful candidates for the technological applications and a lot of studies have been devoted to this polymer . Polyaniline in its emeraldine salt form contains alternating block copolymer of benzenoid and quinoid units (1, 4 bonding or para bonding) and an even oxidation state with equal proportion of benzenoid and quinoid units. Between each benzenoid and quinoid there are different imino and amino groups which are often used as sites for selective acid doping.
It is evident[7, 17-20] that the electrical property of doped PANI is significantly improved due to the incorporation of noble metal nanoparticles such as gold and silver, among which silver has received much attention due to its highest conductivity at room temperature and relatively low cost compared to others. Both PANI and silver display a variety of morphologies on the nanoscale. Their nature, distribution within the composites, and interfacial phenomena are expected to control or affect their electrical properties. In the classical percolation concept, approximately 50-60 mass % of the metal nano-particles in the polymer matrix is needed for the formation of metallic conducting pathways in the three-dimensional composite i.e. for the percolation threshold. In this case the most conducting element are metals and conductivity is therefore very high, as manifested from the earlier reports. Below the percolation threshold, the dispersed nano-particles within the conducting polymer matrices play the role of conducting filler and the conductivity is controlled mostly by the conducting polymer itself i.e. show semiconducting nature [19, 21].
As, only a few effor...
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...ately doped PANI matrix, upon the relaxation dynamics and ac conductivity within a wide frequency and temperature range. Analysis of the experimental data by different models enables us to confirm the common origin of the charge transport and dielectric relaxation of these silver-PANI nano-composites. Qualitative study of the relaxation dynamics of the present systems and estimation of various disorder parameters such as optimal hopping distance, localization lengths etc., would help us to outspread the strategies for the fabrication of new organic semiconducting nano-structured devices. Thus, the present study is not only essential for the rational design of different types of devices, it will also contribute to the general understanding of physics of materials characterized by charge localization and disorder which was not delineated in the previous ones reported.