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

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.