Electrical limit of silver nanowire electrodes: Direct measurement of the nanowire junction resistance

We measure basic network parameters of silver nanowire (AgNW) networks commonly used as transparent conducting electrodes in organic optoelectronic devices. By means of four point probing with nanoprobes, the wire-to-wire junction resistance and the resistance of single nanowires are measured. The resistance $RNW$ of a single nanowire shows a value of $RNW=(4.96±0.18) Ω/μm$⁠. The junction resistance R_J differs for annealed and non-annealed NW networks, exhibiting values of $RJ=(25.2±1.9) Ω$ (annealed) and $RJ=(529±239) Ω$ (non-annealed), respectively. Our simulation achieves a good agreement between the measured network parameters and the sheet resistance R_S of the entire network. Extrapolating R_J to zero, our study show that we are close to the electrical limit of the conductivity of our AgNW system: We obtain a possible R_S reduction by only $≈20%$ (common $RS≈10 Ω/sq$⁠). Therefore, we expect further performance improvements in AgNW systems mainly by increasing NW length or by utilizing novel network geometries.