IntroductionConducting polymers belong to the group of organic semiconductors. They have received considerable attention recently owing to their numerous potential applications in electronic components such as Schottky diodes [1], field-effect transistors (FETs) [2], and electroluminescent diodes [3,4]. Because of the inherent flexibility of organics and their relative ease of processing, as well as the easy tunability of electric properties by means of chemical substitutions, these materials provide new avenues in the development of electronic devices. Furthermore, these materials exhibit a particularity concerning their interaction with gases and vapors [5]. Interacting electrically neutral gas molecules can donate/accept fractional electronic charge, thereby changing the electronic properties of the matrix. The modulation of electrical properties of polymers upon interaction with gas depends on the type of the conducting polymer.The following sections give an overview of the basic properties of conducting polymers that are required to understand the operation of conducting polymer-based gas sensors. The mechanism of interactions between conducting polymers and gas or vapor species that is used as a transduction principle in gas sensors is discussed. Examples of the gas-sensing properties of conducting polymer gas sensors are given. They show how experimental and structural parameters of conducting polymers can influence the sensor characteristics.
Electronic Properties of Conducting PolymersPolymers are typically associated with flexible, processible materials having electrically insulating properties. Although this is true of most polymers, a special class of these materials called conjugated polymers has the electrical and optical properties traditionally associated with metals and semiconductors, yet they retain the mechanical properties and the processibility of plastics [6]. Conjugated polymers Electropolymerization: Concepts, Materials and Applications. Edited by Serge Cosnier and Arkady Karyakin