Contents lists available at ScienceDirect Materials Science in Semiconductor Processing journal homepage: www.elsevier.com/locate/mssp The effect on the impedance characteristics of the metal oxides (Al 2 o 3 and Zno) doping into polyaniline E. Ahlatcıoğlu Özerol a, ⁎ , A. Çelik Bozdoğan b , B. Filiz Şenkal c , M. Okutan b a Department of Bioengineering, Yildiz Technical University, Istanbul, Turkey b Department of Physics, Yildiz Technical University, Istanbul, Turkey c Department of Chemistry, Istanbul Technical University, Istanbul, Turkey ARTICLE INFO Keywords: Polyaniline Metal Oxide ZnO Al 2 O 3 Impedance spectroscopy ABSTRACT In this study, the doping metal oxides; ZnO and Al 2 O 3, (MO for short) into poly (aniline) (PANI) how that affects the dielectric properties have been investigated by the impedance analysis technique. PANI, PANI-Al 2 O 3 and PANI-ZnO were synthesized by chemical oxidative polymerization. Both FTIR and SEM are used to characterize the structure and morphologies of these composites. Dielectric properties of PANI and PANI–MO composites have been performed in the frequency range 100 Hz -1 MHz. It was seen that the values of the dielectric constant and impedance increase with doping Al 2 O 3 and ZnO into PANI. Absorption coefficient (α) and relaxation times (τ) parameters were calculated and it is revealed that the relaxation mechanism changed significantly by the doping of metal oxide into PANI. Moreover, the conductivity properties of PANI-MO composites were performed and it is seen that “s” parameter value correlated Barrier Hoping (CBH) Mechanism. 1. Introduction Organic conducting polymers have a wide range of useful applica- tions due to unusual electronic properties such as good electrical conductivity, low ionization potential and high electron affinity [1]. Among them, PANI has attracted increasing attention owing to low cost, lightweight and high environmental stability in the last decades [2,3]. Because of its unique properties, it has a wide applications in diverse areas such as batteries [4,5], sensors [6,7], electronic devices [8]. More recently, the doping inorganic oxides (CeO 2 , CuO, SnO 2 , TiO 2 , ZnO, Al 2 O 3 ) into PANI allows the modification of its physical properties and the development of new materials in the field of science and technology [9–18]. ZnO has a versatile material due to its wide direct band gap (3.37 eV) with potential applications in short wavelength light emitting devices, sensors and solar cells [19,20]. That is why it is suitable for the use of ZnO to absorbe high-energy photons (UV light) [21]. Cho et al. [22] reports that the polycrystalline ZnO thin films show good luminescent properties. ZnO can also be used at oxide potential application in optoelectronics due to its physical properties. [22,23]. Kennedy et al. reported the electrical and optical properties of ZnO thin films and their results show that electrical conductivity can be controlled by post growth thermal treatments [19]. Eskizeybek et al. [24] synthesized PANI/ZnO nano composites and showed that the thermal stability of PANI/ZnO composites increased with the increasing of the amount of the ZnO nanoparticles in the reaction mixture because of the strong interaction between the polymer and ZnO nanoparticles. Also there are a few reports have been published on the synthesis, morphology, optical, photocatalytical [24–28], electrical and dielectric properties of ZnO-PANI composites [15,18,29–31]. Olson et al. [32] showed the feasibility in making device using these properties. In addition; Booth et al. [33]. performed low- energy implantation of lead ions of various fluences in conducting polypyrrole films and they observed an increasing in charge-carriers. In another research of Booth et al. [34] low-energy platinum were implanted to conducting polymer to gain more conductive film. Besides, they aimed to show that the obtained films could use in sensors. Similarly, Al 2 O 3 is an attractive material because of its higher dielectric constant. Doping Al 2 O 3 into PANI creates a strong interac- tion between polymer and Al 2 O 3 which reinforce dielectric properties of PANI [17,35]. Therefore, it is considered to be a candidate for dielectric applications [36,37]. In this work, PANI, ZnO-PANI and Al 2 O 3 -PANI composites were synthesized by chemical oxidative polymerization. Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron http://dx.doi.org/10.1016/j.mssp.2016.08.016 Received 5 March 2016; Received in revised form 10 June 2016; Accepted 18 August 2016 ⁎ Corresponding author. E-mail address: esma_ahlatcioglu@yildiz.edu.tr (E. Ahlatcıoğlu Özerol). Materials Science in Semiconductor Processing 56 (2016) 357–361 1369-8001/ © 2016 Elsevier Ltd. All rights reserved. crossmark