▎ 摘　　要

The use of graphene materials as conductive inks for flexible and transparent electronics is promising, but challenged by the need for stabilizers, specialized organic solvents, and/or high temperature annealing, severely limiting performance or compatibility with substrates and printing techniques. Here, the development of a scalable water-based graphene oxide ink is reported that can be screen-printed on flexible plastic substrates and subsequently reduced using a 1: 1 mixture of trifluoroacetic acid and hydroiodic acid, thereby creating an electric circuit. The reduced prints exhibit low sheet resistance of 327 Omega sq(-1) for thin semitransparent layers with 37% transmittance. This methodology with postprinting chemical reduction outperforms high temperature annealing, thereby eliminating the need for such a step, which is incompatible with flexible plastic substrates. The strategy relies on low cost, industrially compatible chemicals and can be scaled up for low cost manufacture of roll-to-roll printed electronics.