Transfer-Printed PEDOT:PSS Electrodes Using Mild Acids for High Conductivity and Improved Stability with Application to Flexible Organic Solar Cells

Highly conductive, flexible, and transparent electrodes (FTEs) of PEDOT:PSS films on plastic substrates have been achieved using strong acid treatments. However, it is rare to realize a performance attenuation of PEDOT:PSS FTEs on plastic substrates and flexible optoelectronic devices because of strong acid residues in the PEDOT:PSS matrix. Herein, we develop a feasible transfer-printing technique using mild acids. Because of a mild and weak property of these acids and less acid residues in PEDOT:PSS matrix, the transferred PEDOT:PSS FTEs exhibited a significant enhancement in stability, conductivity (3500 S cm-1), transparency, and mechanical flexibility on plastic substrates. Flexible organic solar cells with the FTEs also showed a remarkable enhancement in power conversion efficiency and stability in the ambient atmosphere. It is expected that the novel transfer-printing technique for making PEDOT:PSS FTEs is also useful in many other types of flexible optoelectronic devices.