Development of Refractive-Index-Matched MTO/Ag/MTO Multilayer Film on Poly(ethylene terephthalate) Substrate

In this study, we fabricate a transparent conductive multilayer film consisting of an Ag layer sandwiched between manganese-doped SnO₂ layers (MTO/Ag/MTO) with a refractive index-matching layer (IML) on a poly(ethylene terephthalate) (PET) substrate. SiO₂ (n = 1.5 @ 550 nm) and MTO (n = 2.7 @ 550 nm) are selected as the low and high-refractive-index materials. In order to evaluate the reflectance (ΔR_{550 nm}) and color difference (Δb*) properties relate to the electrode pattern visibility of transparent conducting oxide (TCO) films, we systematically investigate the influence of the SiO₂/MTO IMLs on the MTO (40 nm)/Ag (13 nm)/MTO (40 nm) TCO film. We find that the optical transmittance of all fabricated films are above 85% at a wavelength of 550 nm. The thickness of the IMLs exhibiting optimum characteristics is SiO₂ (70, 80, 90 nm)/MTO (10 nm). In addition, the ΔR_{550 nm} and Δb* of the optimized films are 2.5, 2.1, and 1.6%, and 1.4, 1.1, and 0.7, respectively.