Silver alloy-based metal matrix composites: a potential material for reliable transparent thin film heaters

In this study, a flexible Zn(3 at%)-SnO x /AgTi 0.0007 Cr 0.0067 /Zn(3 at%)-SnO x (Zn-SnO x /ATC/Zn-SnO x ) multilayer transparent conducting thin film on a polyethylene terephthalate (PET) substrate was fabricated by on-axis radio frequency (RF) magnetron sputtering at room temperature to obtain a reliable and transparent thin film heater. To optimize the composition of the Ag-Ti-Cr alloy, which is more durable in high-temperature and humid conditions than the Ag thin film, we performed the constant temperature-humidity test for Ag-Ti-Cr thin films of various compositions deposited by continuous composition spread sputtering. The Zn-SnO x /Ag-0.07 at%Ti-0.67 at%Cr/Zn-SnO x multilayer thin film exhibited a higher transmittance of around 89% and enhanced durability compared with that of the Zn-SnO x /Ag/Zn-SnO x multilayer thin film. Moreover, the mechanical flexibility was confirmed through a bending test. The Zn-SnO x /ATC/Zn-SnO x multilayer thin film heater took approximately 40 s to attain a temperature of 100 °C when the voltage was 6.5 V, and it exhibited stable heating operation even after remaining in a heating state for 2 h. In addition, the durable and transparent Zn-SnO x /ATC/Zn-SnO x multilayer thin film heater exhibited uniform heat distribution and reliable thin film heater performance. Hence, the suggested reliable and transparent Zn-SnO x /ATC/Zn-SnO x multilayer thin film heater is applicable to multifunctional smart windows and anti-fogging systems. A Zn-SnO x /optimized Ag-0.07 at%-0.67 at%Cr/Zn-SnO x multilayer thin film with reliable and reversible heating performance as a flexible transparent thin film heater was fabricated.