An conductive ink based on silver oxide complex for low-temperature sintering with dense conductive paths

In the context of advancing flexible electronic technologies, conductive ink has garnered significant scholarly interest. Wherein, metal-organic decomposition (MOD) ink composed of silver precursors, complexing agents, and volatile organic solvents, has been widely studied due to its advantages such as simple preparation, long shelf life, high jetting stability, and low-temperature processing. However, the volumetric reduction of MOD ink frequently surpasses 80%, which typically could lead to multiple voids and breaks in the conductive film, resulting in poor conductivity. Meanwhile, a high temperature of above 180 °C is usually required for the MOD ink to be converted into conductive film. Nevertheless, it is imperative for the ink to be deposited onto substrates at low temperatures. Herein, a low temperature conducting ink with multiple silver source precursors has been developed. The results show that after sintering at 100 °C for 40 min on a polyimide (PI) substrate, the resistivity of the silver film was 16.8 µ Ω cm, which is only ten times higher than that of bulk silver, and the silver film with good uniformity and conductivity can be formed. Defects, such as voids and cracks, are significantly reduced through the gradient decomposition of different silver source during the sintering process. The formula of ink and the effects of sintering temperature on the microstructure and electrical properties of silver ink thin films have been studied in details using XRD, SEM, EDX, and four-probe techniques.