Tailoring the Opto-Electronic Properties of Oxide-Metal-Oxide Transparent Electrode Using Cu Seed Layer

Abstract

The oxide-metal-oxide architecture is a promising approach for the development of the high-performance indium-free transparent electrode (TE), which is a key component of various optoelectronic applications such as solar cells, organic LEDs, and touchscreen panels. Here in this work, we have shown high-performance TE consisting of TiO2/Ag/TiO2 (TAT), with the incorporation of a copper seed layer. The seed layer increases the wettability and improves the adhesion of deposited Ag film on the bottom TiO2 layer. Before the experimental realization, optical modeling is performed by using MATLAB code based on the transfer matrix method. The optimum thickness obtained from the simulation is 30 nm for both undercoat and overcoat TiO2 with the average transmittance in the visible region >85% with the Ag thickness of 9nm. With inputs from the optical modeling, TEs were experimentally realized with and without the Cu seed layer. It has been found that the TE with an additional sputtered Cu (1 nm) seed layer is essential for the smooth growth of silver film and shows better electro-optical performance (sheet resistance < 10 and average transmittance in the visible spectral range > 80%) than TAT-TE without any seed layer. The electro-optical and morphological properties of the TiO2/Cu/Ag/TiO2 structure make it suitable for optoelectronic applications.