Modulation of the Optoelectrical Properties of Indium Tin Oxide (ITO) Multilayer Transparent Conductive Films by a Cu Seed Layer and Au Interlayer

Abstract Transparent conductive films (TCFs) have attracted extensive attention due to their broad applications in optoelectronic devices. However, the Volmer–Weber growth mode of ultrathin metal films generally results in poor film continuity, introducing an inherent tradeoff between sheet resistance and optical transmittance, which fundamentally constrains the overall optoelectronic performance of TCFs. To overcome this limitation, we introduced an ultrathin Cu seed layer to regulate the growth behavior of Au films, subsequently fabricating an ITO/Cu/Au/ITO multilayer transparent conductive film. The optimized multilayer film achieved a low sheet resistance of 8.47 ± 0.33 Ω/sq, a high visible transmittance of 89.1%, and a figure of merit (FoM) of 37.23 × 10–3 Ω–1, yielding roughly 1.7-fold enhancement in FoM over the control Cu/Au/ITO sample annealed at 450 °C. Scanning electron microscopy (SEM) observations revealed that the introduction of the ultrathin Cu seed layer effectively reduced the continuity threshold of the Au film, substantially enhancing the uniformity and continuity of the metallic layer, which facilitates a stable conductive network. Atomic force microscopy (AFM) and X-ray diffraction (XRD) analyses further demonstrated that post-annealing treatment promoted grain growth and enhanced the crystallinity of the multilayer films. These findings indicate that Cu seed layer and multilayer optimization provide an effective strategy for regulating the growth of ultrathin Au films and concurrently enhancing both the electrical and optical properties of TCFs.