Investigation of low resistance transparent F-doped SnO2/Cu bi-layer films for flexible electronics

• The FTO/Cu multilayer films structures were prepared on polymer substrates.
• The films possessed the figure of merit of 11.4 × 10−3 Ω−1.
• The change in electrical and optical properties were discussed and explained possibly.
• The mechanism of the changes of electrical and optical properties was proposed.

F-Doped SnO2 (FTO)/Cu bi-layer films were grown at room temperature on polymer substrates with different copper layer thickness by radio frequency (RF) magnetron sputtering of Cu and pulsed laser deposition of FTO. We investigated the structural, electrical, and optical properties of bi-layer films at various thicknesses of Cu layer. As the Cu layer thickness increases, the resistivity decreases. The conduction mechanism involves carrier injection from metal to oxide carrier injection from metal to oxide prior to the formation of a continuous metal conduction pathway. The resistivity value of 7.1 × 10−5 Ω cm with a carrier concentration of 1.7 × 1022 cm−3 was obtained at the optimum Cu (7 nm) layer thickness. The photopic averaged transmittance and figure of merit are 82.0%, and 1.1 × 10−2 Ω−1 for the FTO (50 nm)/Cu (7 nm) bi-layer films, respectively.