Characteristics of indium zinc oxide/silver/indium zinc oxide multilayer thin films prepared by magnetron sputtering as flexible transparent film heaters

Highlights: • Indium Zinc Oxide (IZO)/Ag/IZO multilayer used in flexible Thin Film Heaters (TFHs). • Uniform heat distribution of the heater before and after bending test. • IZO/Ag/IZO multilayer with 15-nm Ag layer was demonstrated to be the best combination. - Abstract: Indium zinc oxide/silver/indium zinc oxide multilayer structures with a very low resistivity and high transmittance were deposited on a polyethylene terephthalate substrate by DC magnetron sputtering. The electrical, optical, mechanical, and thermal properties of the multilayer films were investigated at different Ag layer thicknesses (10–20 nm). The multilayers demonstrated relatively constant resistance change (∆R/ R₀) over repeated bending tests with a radius of 8 mm. Efficient Joule heating could increase the operating temperature of the film heaters (7.3 Ω/□) to 73.7 °C in ~20 s at 3 V; moreover, the heat distribution remained uniform after bending tests. A high transmittance (84.7%) at a wavelength of 550 nm and low sheet resistance (7.3 Ω/□) of the optimized multilayer was obtained at an Ag layer thickness of 15 nm. These results indicate that the multilayers are promising as transparent film heaters for next-generation flexible applications.