## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Substrate** **(Thickness, Refractive Index)**} & \multicolumn{2}{c}{**Transmittance**} \\ \cline{2-3}  & **Bare AgNW** & **AgNW with UAPR** \\  & & **Overcoating (3 μm)** \\ \hline PET (125 μm, 1.64) & 90.6 \(\pm\) 0.3 & 91.3 \(\pm\) 0.4 \\ \hline PEN (125 μm, 1.77) & 88.9 \(\pm\) 0.2 & 90.1 \(\pm\) 0.3 \\ \hline ITO (100 nm, 1.92)/PET & & \\ (125 μm, 1.64) & 84.2 \(\pm\) 0.2 & 85.7 \(\pm\) 0.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Optical transmittance of Ag nanowire TEs with and without UAPR on various substrates. Figure 2: SEM images of (**a**) the bare Ag nanowire electrode and (**b**) the Ag nanowire electrode with UAPR coating. reliability testing of TEs in industry. The bare Ag nanowire electrodes had an optical transmittance of \(\sim\)90.6% before exposure, which fell to \(\sim\)89.0% during exposure to air. On the other hand, there was no significant change in the optical transmittance of the Ag nanowire TEs with the UAPR coating (\(\sim\)91.3% both before and after 180 h of exposure). The trend in the sheet resistance was similar to that for the optical transmittance. While bare Ag nanowire electrodes exhibited an increase in the sheet resistance from \(\sim\)51.32 ohm/sq to 73.22 ohm/sq after 180 h of exposure, the UAPR-coated Ag nanowire TEs maintained their initial sheet resistance over the entire period (Figure 3b). In ambient air, the surface of Ag nanowires corrodes, leading to the formation of oxide or sulfide derivatives on the surface. The reduction in the cross-sectional area of the nanowires due to this corrosion restricts the current flow, thus lowering the electrical conductivity of Ag nanowire TEs [21, 25]. In addition, the oxide or sulfide particles that form on the Ag nanowire surface due to the corrosion increase the probability of light reflecting at the surface of the electrode [25], in turn reducing its optical transmittance. After coating the nanowires with UAPR, however, contact between water vapor or gas molecules in the air with the surface of the nanowires is effectively prevented. Furthermore, in stability testing with nitric acid, Ag nanowire TEs with UAPR coating showed no significant change after 2 h of immersion in 4 vol% nitric acid, while bare Ag nanowire electrodes lost their electrical conductivity after only 30 min of exposure. In summary, in the present study, the optical transmittance and sheet resistance of the proposed UAPR-coated Ag nanowire TE were very stable under prolonged exposure, which proves the effectiveness of the UAPR coating in enhancing the ambient stability of Ag nanowire TEs. During the fabrication process of electronic devices that employ Ag nanowire TEs, the possibility of mechanical damage to the electrodes due to external wiping forces is high. Because the adhesion of Ag nanowires to the polymeric substrate is low, external wiping forces can remove Ag nanowires from the substrate, decreasing the electrical conductivity of Ag nanowire TEs. Therefore, protecting Ag nanowires from external wiping damage is crucial for the industrial use of Ag nanowire TEs. To investigate the effect of the UAPR coating on the resistance of Ag nanowire TEs to wiping damage, an artificial wiping force was applied to Ag nanowire electrodes with and without the UAPR coating using a cotton textile soaked in IPA. Figure 4a displays the variation in the optical transmittance of the Ag nanowire electrodes as a function of the number of times the wiping force was applied. The bare Ag nanowire electrode had an optical transmittance of \(\sim\)90.6% before starting the test, which increased to \(\sim\)91.0% after the first wiping cycle and then to \(\sim\)91.9% after six wiping cycles. The optical transmittance of the bare Ag nanowire TEs thus approached that of bare PET film (\(\sim\)92.1%) because most of the Ag nanowires were removed from the PET substrate due to the wiping damage.