Investigation of Ag-TiO₂ Interfacial Reaction of Highly Stable Ag Nanowire Transparent Conductive Film with Conformal TiO₂ Coating by Atomic Layer Deposition

The atomic layer deposition (ALD) technique is applied to coat Ag nanowires (NWs) with a highly uniform and conformal TiO 2 layer to improve the stability and sustainability of Ag NW transparent conductive films (TCFs) at high temperatures. The TiO 2 layer can be directly deposited on Ag NWs with a surface polyvinylpyrrolidone (PVP) coat that acts a bed for TiO 2 seeding in the ALD process. The ALD TiO 2 layer significantly enhances the thermal stability at least 100 fold when aged between 200–400 °C and also provides an extra function of violet-blue light filtration for Ag NW TCFs. Investigation into the interaction between TiO 2 and Ag reveals that the conformal TiO 2 shell could effectively prevent Ag from 1D-to-3D ripening. However, Ag could penetrate the conformal TiO 2 shell and form nanocrystals on the TiO 2 shell surface when it is aged at 400 °C. According to experimental data and thermodynamic evaluation, the Ag penetration leads to an interlayer composed of mixed Ag–Ag 2 O-amorphous carbon phases and TiO 2– x at the Ag–TiO 2 interface, which is thought to be caused by extremely high vapor pressure of Ag at the Ag–TiO 2 interface at a higher temperature (e.g., 400 °C).