Research on femtosecond laser welding process of silver nanowire transparent electrodes

Abstract

With the continuous development of flexible transparent electrodes, silver nanowires have been widely used due to their excellent optoelectronic properties and flexibility. However, their progress has been hindered by high contact resistance. In this study, femtosecond laser post-processing was applied to the silver nanowire transparent electrodes, and the effect of laser power density on the welding of silver nanowires was investigated. The results showed that femtosecond laser could achieve welding between silver nanowires, but excessively high laser energy density could cause the melting of the nanowires. When the femtosecond laser energy density reached the critical energy density of approximately 2546 J·m−2, at which nanowires underwent spheroidization, the average sheet resistance of the silver nanowire electrodes was minimized to 18.89 Ω·sq−1, and the figure of merit (FoM) of the electrodes reached its maximum at 126.99, which was close to twice the initial value. Moreover, the non-uniformity factor (NUF) was also small, at 1.6%, indicating good conductivity and uniformity. Additionally, the influence of femtosecond laser irradiation on the transmittance of the silver nanowire transparent electrodes was insignificant, and the number of effective pulses had no obvious effect on the welding efficiency of the silver nanowires.

Keywords

• Silver nanowires
• Femtosecond laser
• Energy density
• Sheet resistance
• FoM
• Effective pulses