Selective laser ablation preparation of Ag grid transparent electrodes with fractal-combined structures and optimization of fractal grid pitch

Abstract

New fractal-structured patterns with different grid period combinations were designed and applied to Ag grid transparent electrodes (TEs). Based on the principle of decreasing or increasing Ag grid line densities in local areas, the optical transmittance or electrical conductivity of the resulting Ag grid TEs could be selectively enhanced, thus effectively improving its comprehensive performance. Fractal-combined Ag grid TEs with different combined periods were firstly prepared by selective laser ablation of sputtered Ag films, and compared with the corresponding regular periodic Ag grid TEs to determine the optimal combined periods. The results indicated that the combined periods of 4 and 9 enabled the Ag grid TE to have a relatively high figure of merit of 4.92 × 10–2 Ω−1. This optimal fractal-combined Ag grid TE was chosen to optimize grid pitch for further comprehensive performance improvement. Using a large grid pitch of 1.1 mm could achieve the best trade-off between optical transmittance and electrical conductivity, and produced the best comprehensive performance with the maximum figure of merit of 5.17 × 10–2 Ω−1. The fractal-combined structure provides a unique scheme for flexibly designing and preparing grid patterns in metal TEs.