Fabrication of flexible electronics by screen printing with PEDOT: PSS/graphene composite ink

Abstract

Recently, flexible and wearable electronics have received increasing attention with many emerging applications. Compared with traditional electronic devices on the rigid substrates, flexible electronics provide great potential in portable and wearable applications. PEDOT: PSS, as a conductive polymer, has high mechanical flexibility, making it suitable for the fabrication of wearable and deformable electronic devices such as organic transistors, photovoltaics, and wearable sensors. This intrinsic flexibility is crucial in enabling next-generation flexible electronics that are ultrathin, transparent, and wearable. However, the electrical conductivity of pristine PEDOT: PSS is often below 1 S/cm, which is insufficient for many electronic devices such as organic photovoltaics and organic transistors. In this work, we synthesized PEDOT: PSS/ Graphene composite to enhance the electrical performance of PEDOT: PSS. To achieve low-cost and scalable fabrication, we explored a screen-printing process to print the conductive PEDOT: PSS/ Graphene patterns onto various substrates. The PEDOT: PSS/ Graphene composite ink was developed for the screen-printing process with the ink viscosity and flowability adjusted by different ratio of polyethylene oxide (PEO) additive. Different weight ratios of graphene and PEO were studied to achieve stable and printable ink for the device fabrication. The effect of the ink composition on the pattern resolution and electric performance was experimentally characterized to obtain the trade-off between ink printability, electrical properties and printing resolution. Using the synthesized PEDOT: PSS/graphene ink, the printed circuits demonstrated excellent flexibility in the bending tests. The circuits provided stable electrical response under bending and twisting deformation and under hundreds of bending cycles, which provide a promising approach toward scalable fabrication of flexible wearable electronics.