Transport and structural properties of polyaniline doped with monovalent and multivalent ions

Mechanism of charge transport in poly(2,5-dimethoxyaniline)

“…It can be seen from Table II that the density of states at the Fermi level; N͑E F ͒ of all the PDMA samples lies in the range ϳ10 17 -10 18 cm −3 eV −1 which is in good agreement with the values reported earlier for other conjugated polymers. 6,10,[13][14][15][16][17][18][19] Our results are consistent with the Mott's requirement that ␣R ӷ 1 and W ӷ k B T for conductivity by hopping to distant sites ͑Table II͒. The temperature dependent activation energy ͓Fig.…”

“…24 At the same time it restricts the mobility of charge carriers, whereas, the partial/little crystallinity, shows a little ordering in the polymer chain which could be attributed to the benzenoid structure where the polaronic lattice supports the mobility of charge carriers and hence, a good conductivity of the polymer PDMA. It has been reported 10,24 in literature that the magnitude of dc conductivity increases with increase in number of benzenoid ring units in PDMA back-bone. The dependence of room temperature dc conductivity on the ratio of binary oxidants indicates ͑Table I͒ that the extent of benzenoid structure is maximum in sample PDMA3, which has higher conductivity than other samples of PDMA.…”

“…Hence the activation energy ͑Table I͒ of PDMA is more than that observed in case of unsubstituted PANI. 6,7,9,10 Eqs. ͑7͒ and ͑8͒ give the slope T 0 , 12,13,19 of the plots of log dc versus T −1/4 ͓Fig.…”

“…5 Prior to any device application, the study of charge generation, and its transport in this system are very important. PANI has been extensively investigated [6][7][8][9][10][11] for its dc electrical conductivity and the experimental data has been analyzed by application of Mott's variable range hopping ͑VRH͒ model. It seems worthwhile to mention here that Mott's VRH model 12 has been extensively applied to amorphous inorganic semiconductors over the last four decades with varying degree of success in polypyrrole, poly͑3-decylpyrrole͒, polythiophene, poly͑3-methylthiophene͒, poly͑3-hexylthiophene͒, poly͑3-octylthiophene͒, emeraldine form of PANI.…”

“…It seems worthwhile to mention here that Mott's VRH model 12 has been extensively applied to amorphous inorganic semiconductors over the last four decades with varying degree of success in polypyrrole, poly͑3-decylpyrrole͒, polythiophene, poly͑3-methylthiophene͒, poly͑3-hexylthiophene͒, poly͑3-octylthiophene͒, emeraldine form of PANI. [6][7][8][9][10][11][13][14][15][16][17][18][19][20] The VRH mechanism is also reported 21 in poly͑o-methoxyaniline͒ in the small temperature range 298-398 K. However, no report is available in literature on the temperature dependence of dc electrical conductivity of PDMA. The present paper is a report of our measurements of dc electrical conductivity in the wide temperature range 6-303 K on various samples of PDMA.…”