Low electrical resistivity of a graphene–AgNHPs based ink with a new processing method
The purification and separation of nano-Ag particles is difficult because of the small size, it restricts the applications of nano-Ag. In this study, the AgNHPs solution was purified and separated with a membrane separation-centrifugation cleaning method, for use as the ink of printed electronics. Meanwhile, we prepared inkjet-printed patterns of conductive inks consisting of AgNHPs and graphene (GE) in different contents. It is found that high dispersity and low electrical resistivity of AgNHPs inks can be obtained by using membrane separation-centrifugation cleaning method. The AgNHPs particles show excellent dispersion and the electrical resistivity of the AgNHPs solution is 11.2 × 10−6 Ω cm at 150 °C, it increases the electrical conductivity of GE–AgNHP. It is also found that GE can significantly improve the electrical conductivity of the patterns when sintering is done at relatively low temperatures. When the GE content is 0.15 mg mL−1, the resistivity is the lowest. For instance, when sintering is done at 150 °C, the resistivity is 2.5 × 10−6 Ω cm that is 13% of that of the AgNHPs conductive ink; after sintering at 50 °C, this ratio is 2%. This study on GE–AgNHPs conductive inks sintered at low temperatures should further the development of flexible touch screens.