Core/shell copper nanowire networks for transparent thin film heaters

Copper nanowires (Cu NWs) appear as the strongest alternative to silver nanowires (Ag NWs) in transparent conductors. Cu NWs; however, are more prone to oxidation compared to Ag NWs even at room temperature. This problem becomes more severe when Cu NWs are used as transparent thin film heaters (TTFHs). In this work, we have utilized ALD deposited zinc oxide (ZnO) shell layers, and provide a comparison with typically used aluminum oxide (Al₂O₃) shell layers to improve the TTFH performance. While Cu NW network TTFHs barely withstood temperatures around 100 °C, critical thickness of ALD deposited Al₂O₃ and ZnO layers were determined to find out TTFH limits. Maximum stable and reproducible temperatures of 273 °C and 204 °C were obtained for Al₂O₃ and ZnO deposited Cu NW network TTFHs, respectively. An extensive parametric study on the NW density and oxide type in conjunction with the electrical conductivity and optical transmittance was conducted. A remarkably high heating rate of 14 °C s^-1 was obtained from the fabricated core/shell networks with improved oxidation stability under ambient and high humidity conditions. Finally, these high performance core/shell Cu NW network TTFHs were utilized as efficient defrosters.