We demonstrated conformal Al2O3 passivation via atomic layer deposition (ALD) of a flexible Ag network electrode possessing a high aspect ratio. The Ag network electrode passivated by the ALD-grown Al2O3 film demonstrated constant optical transmittance and mechanical flexibility relative to the bare Ag network electrode. Owing to the conformal deposition of the Al2O3 layer on the high aspect ratio Ag network electrode, the electrode exhibited more favorable stability than its bare Ag-network counterpart. To demonstrate the feasibility of Al2O3 passivation via ALD on a flexible Ag network, the performances of flexible and transparent thin-film heaters (TFHs) with both a bare Ag network and that passivated by ALD-grown Al2O3 were compared. The performance of Al2O3/Ag network-based TFHs was minimally altered even after harsh environmental tests at 85% relative humidity and a temperature of 85 °C, while the performance of bare electrode-based TFHs significantly deteriorated. The improved stability and reliability of the Al2O3/Ag network-based TFHs indicate that the ALD-grown Al2O3 film effectively prevents the introduction of moisture and impurities into the Ag network with a high aspect ratio. The improvement in the stability of the Ag network through Al2O3 passivation implies that the ALD-grown Al2O3 film represents a promising transparent and flexible thin film passivation material for high quality Ag network electrodes with high aspect ratios.

Despite the excellent performance of MXene−Ag nanowire (MA) composite transparent conductive electrodes (TCEs), they rapidly and severely degrade in ambient and humid environments. To address this critical issue, we developed conformal polytetrafluoroethylene (PTFE) passivation thin films prepared using magnetron sputtering at room temperature. Compared to the PTFE passivated electrode, the nonpassivated bare MA-composite electrode exhibited a considerably increased sheet resistance, and the electrode flexibility and electromagnetic interference (EMI) shielding efficiency (SE) degraded rapidly over time because the moisture and impurities severely oxidized the MXene layer in the harsh testing environment. However, the MA-composite electrode with PTFE passivation shows constant sheet resistance, transmittance, flexibility, and EMI SE, even after the 85 °C−85% relative humidity (RH) test. Compared to the nonpassivated MA-electrode-based thin film heaters (TFHs), the PTFE-passivated MA-composite electrode-based TFHs exhibited improved stability and reliability, indicating that the sputtered PTFE film effectively prevented the moisture and impurity penetration of the MA-composite electrodes.