Zinc and Zinc Oxide Nanowires Grown on PEDOT:PSS/SiO 2 Conductive Polymer Thin Films by Vapor Phase Transport Deposition
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Zinc and Zinc Oxide Nanowires Grown on PEDOT:PSS/SiO2 Conductive Polymer Thin Films by Vapor Phase Transport Deposition Matthew P. Chamberlin, Costel Constantin Department of Physics and Astronomy, James Madison University, Harrisonburg, VA 22801, U.S.A. ABSTRACT Easily available spin coating and vapor phase transport deposition techniques offer tremendous possibilities in fabricating inorganic/organic heterojunctions. We present here preliminary results from different thin film growth mechanisms including: i) PEDOT:PSS/Znnanowires/SiO2, ii) Zn-nanowires/PEDOT:PSS/SiO2, and iii) ZnO-nanowires/PEDOT:PSS/SiO2. The preliminary scanning electron microscopy and energy dispersive spectroscopy results show that Zn nanowires bond better to the non-annealed PEDOT:PSS thin films. It was also found that ZnO nanowires grow homogeneously on annealed PEDOT:PSS surfaces with colloidal Au nanoparticles as bonding reaction catalysts. INTRODUCTION PEDOT:PSS (poly 3,4-ethylenedioxythiophene:polystyrenesulfonate) is an organic ptype polymer that has been widely studied due to its high electrical conductivity and excellent film forming abilities [1]. It is easily processed from aqueous solutions, exhibits high transparency in the visible range, and is remarkably stable under environmental, thermal, and mechanical stresses [2]. PEDOT:PSS has been used in antistatic coatings and pyroelectric sensors, and is commonly employed as a hole-injecting/transport layer in organic electronics such as light emitting diodes, field effect transistors, and photovoltaic cells [3-6]. The addition of inorganic or metallic nanostructures to form nanocomposites has recently emerged as a popular method of modifying the properties of such polymers. The incorporation of semiconducting zinc oxide (ZnO) nanoparticles and nanowires is of particular interest in the formation of these hybrid materials because ZnO has a wide direct band gap (~3.3 eV) and a large exciton binding energy (~60 meV). ZnO is also easily manufactured, low cost, and nontoxic. Hybrid materials formed with ZnO nanoparticles have been widely studied for their use as active layers in organic devices [7]. However, the incorporation of ZnO nanowires and nanorods into materials suitable for use as anode layers is also possible, and studies done on such nanocomposites are less common [8]. Typical techniques for fabricating these nanostructures include sol-gel colloidal chemical deposition, chemical vapor deposition, sputter deposition and laser ablation deposition [9-11]. We present here the results from the growth of Zn and ZnO nanowires on PEDOT:PSS/SiO2 thin films using a simple vapor phase transport deposition technique and a Au-nanoparticle monolayer to catalyze the ZnO-nanowire growth. These experiments constitute preliminary interfacial studies that will contribute to our understanding of inorganic/organic heterojunctions between Zn/ZnO nanowires and PEDOT:PSS polymers.
EXPERIMENT Throughout the entire study we used SiO2 substrates that were 1 cm x 1 cm in size and with a thickness of 1 mm
