Semiconducting properties of polypyrrole films in aqueous solution
Semiconducting properties of polypyrrole films in aqueous solution
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DOI：
10.1007/s100080050174
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发表时间：
1999-09
影响因子：
2.5
通讯作者：
U. Rammelt;Sven Bischoff;M. El-Dessouki;R. Schulze;W. Plieth;L. Dunsch
中科院分区：
文献类型：
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作者：
U. Rammelt;Sven Bischoff;M. El-Dessouki;R. Schulze;W. Plieth;L. Dunsch
采用光电流谱法结合电化学阻抗谱法研究了阴离子性质对聚吡咯膜电导率的影响。如所示，聚吡咯薄膜在负电位下的导电性可以从半导体到离子导电状态变化，这取决于电聚合过程中加入的电荷补偿反阴离子的大小。当插入小阴离子时，还原的聚吡咯表现出半导体性质，在还原过程中释放聚合物基质。聚合物可以被认为是由半导体层和多孔层组成的两层系统。对不同厚度聚吡咯薄膜的测量表明，半导体层的位置在电极/聚合物界面上。半导体层的欧姆电阻在1-5 kΩ范围内，电容接近100-500 nF，平带电位为- 0.62 VSCE。如果加入较大的阴离子，则在还原过程中发生阳离子插入，此时聚合物中的电解质含量相对较高，聚合物的行为类似于离子导体。并以甲基磺酸为小阴离子，聚苯乙烯磺酸为大阴离子为例进行了讨论。
The influence of the nature of the anions on the conductivity of polypyrrole films in aqueous solution was investigated by photocurrent spectroscopy combined with electrochemical impedance spectroscopy in dependence on the potential. As demonstrated, the conductivity of polypyrrole films at negative potentials can vary from a semiconducting to an ionic conducting state, depending on the size of the charge-compensating counter-anion incorporated during the electropolymerization. The reduced polypyrrole shows semiconducting properties when small anions are inserted, releasing the polymer matrix during the reduction process. The polymer can than be considered as a two-layer system, consisting of a semiconducting layer and a porous layer. Measurements at different thickness of polypyrrole films have shown that the position of the semiconducting layer is in the electrode/polymer interface. The ohmic resistance of the semiconducting layer is in the range 1–5 kΩ, the capacitance approaches a value of 100–500 nF and the flatband potential is −0.62 VSCE. If large anions are incorporated, cation insertion takes place during reduction, the electrolyte content in the polymer then is relatively high and the polymer's behaviour is similar to that of an ionic conductor. The results are presented and discussed together with the example of methylsulfonate as a relatively small anion and polystyrenesulfonate as a large anion.