Investigation of Ag-TiO Interfacial Reaction of Highly Stable Ag Nanowire Transparent Conductive Film with Conformal TiO 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 layer to improve the stability and sustainability of Ag NW transparent conductive films (TCFs) at high temperatures. The TiO layer can be directly deposited on Ag NWs with a surface polyvinylpyrrolidone (PVP) coat that acts a bed for TiO seeding in the ALD process. The ALD TiO 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 and Ag reveals that the conformal TiO shell could effectively prevent Ag from 1D-to-3D ripening. However, Ag could penetrate the conformal TiO shell and form nanocrystals on the TiO 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-AgO-amorphous carbon phases and TiO at the Ag-TiO interface, which is thought to be caused by extremely high vapor pressure of Ag at the Ag-TiO interface at a higher temperature (e.g., 400 °C).