Functionalization of Silver Nanowires Surface using Ag−C Bonds in a Sequential Reductive Method Muhammad Y. Bashouti,* ,† Sebastian Resch,* ,∥ Jü rgen Ristein, ‡ Mirza Mac ̌ kovic ́ , § Erdmann Spiecker, § Siegfried. R. Waldvogel, ∥ and Silke. H. Christiansen †,⊥ † Physics Department, Max-Planck-Institute of the Science of Light, Gü nther-Scharowsky-Str. 1, Erlangen D-91058, Germany ∥ Department for Organic Chemistry Johannes Gutenberg-University Duesbergweg 10-14, Mainz D-55128, Germany ‡ Department for Laser Physics, University of Erlangen-Nü rnberg, Staudtstrasse 1, Erlangen D-91058, Germany § Institute of Micro- and Nanostructure Research (WW9) & Center for Nanoanalysis and Electron Microscopy (CENEM), University of Erlangen-Nü rnberg, Cauerstrasse 6, 91058 Erlangen, Germany ⊥ Institute of Nanoarchitecture for Energy Conversion, Helmholtz-Center Berlin (HZB), Hahn-Meitner-Platz 1, Berlin D-14109, Germany * S Supporting Information ABSTRACT: Silver nanowires (Ag-NW) assembled in interdigitated webs have shown an applicative potential as transparent and conducting electrodes. However, upon integration in practical device designs, the presence of silver oxide, which instantaneously forms on the Ag-NW surfaces in ambient conditions, is unwanted. Here, we report on the functionalization of Ag-NWs with 4-nitrophenyl moieties through A-C bonds using a versatile two step reduction process, i.e., ascorbate reduction combined electrografting. We show that 40% of the Ag atop sites were terminated and provide high surface stability toward oxidation for more than 2 months while keeping the same intrinsic conductivity as in bulk silver. KEYWORDS: silver nanowires, transparent electrodes, Ag−C bonds, electrografting, XPS, surface functionalization T he successful application of transparent conducting films (TCF) such as indium tin oxide (ITO) or aluminum doped zinc oxide (AZO) in optoelectronic devices such as lasers, light-emitting diodes (LEDs), solar cells, or hand-held electronics has fueled a huge interest to further develop those TCFs using inexpensive, easy-to-process (ideally with low thermal budget) materials that are ideally earth abundant, unlike indium and nontoxic. 1 ITO is the most commonly used TCF and serves as a benchmark in terms of high optical transparency in the visible spectral range and at the same time good electrical conductivity. 1 Major disadvantages of ITO are brittleness and limited indium availability with a forecasted strategic reach of less than 10 years if usage continues as of today. AZO is an alternative TCF without rare components; however, the conductance of the layer at high transmission lacks behind the ITO performance. Extensive research goes now into the exploration of nanocomposite alternatives to ITO and AZO using, e.g., silver nanowires (Ag-NW) in interdigitated webs that form a flexible electrode which relies on easy, cost efficient, and low thermal budget synthesis based on simple beaker-type chemistries. 2,3 The major drawback of these Ag-NWs is that they oxidize substantially in ambient conditions at their large exposed surface area. 4 The unwanted immediate oxidation and the interface induced, increased resistivity of the Ag-NW webs with time that need to be controlled and ideally hindered through surface functionaliza- tion. Moreover, attachment of functional groups to the Ag-NW surfaces is expected to permit precise work function engineer- ing. 5,6 Through work function tuning, Ag-NW webs as an external electrode on a semiconductor device, can be adapted to optimize band alignment at the metals/semiconductor interface i.e. a so-called Schottky barrier forms. 7 Despite the fact that sulfur-terminated silver or gold surfaces are used successfully in contemporary electronic devices, little is known about the carbon-terminated Ag-NW surface chemistry through Ag−C bonds and the bond stability in ambient conditions. 8 Electrografting is an easy to perform wet chemical protocol to tailor the properties of an electrode surface, and can be applied to the functionalized Ag-NW web electrode as well. 9−13 In general, electrografting refers to the electrochemical reaction that permits organic layers to be attached to solid conducting substrates. This definition can be extended not only to reactions involving an electron transfer between the working substrate and the functional group, but also to examples where Received: July 29, 2015 Accepted: September 22, 2015 Letter www.acsami.org © XXXX American Chemical Society A DOI: 10.1021/acsami.5b06830 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX