Abstract
Conductive electrodes are major components of flexible optoelectronic devices. However, existing materials are either very conductive but brittle (e.g., ITO [indium tin-oxide]), or non-brittle but less conductive, with an environment-dependent conductivity (e.g., PEDOT:PSS [poly-(3,4 ethylenedioxythiophene): poly (styrene sulfonic acid)]). Here, we propose a new design that simultaneously takes advantage of both the high conductivity of ITO and the high flexibility of PEDOT:PSS. In our design, a PEDOT:PSS interface is inserted between the film substrate and the ITO layer, creating a hybrid layered structure that retains both its high conductivity and high stability, when the film is deformed. The rational behind the creation of this structure, is that PEDOT:PSS, used as an interface between the locally delaminated ITO layer and the substrate, substantially reduces the detrimental effects of cracks on the electrode's conductivity. These results open the path for a new generation of transparent electrodes in advanced flexible devices. Layered electrodes with high conductivity and flexibilityHigh conductivity and flexibility are preferred for flexible electrodes but they usually don't blend well in one single material. Now the combination is achieved in a layered hybrid film. A team led by Prof Gilles Lubineau from King Abdullah University of Science and Technology, Saudi Arabia design layered transparent electrode with both high flexibility and high conductivity. A thin conductive layer of polymeric PEDOT:PSS is spun-coat on the flexible PET substrate, then the ITO layer is sputtered on top of the PEDOT:PSS layer at low temperature. Despite a simple process, the layered structure combines the advantages of ITO and PEDOT:PSS to show high conductivity under macroscopic strain up to 30%. This approach showcases a delicate way to avoid drawback of the brittleness of ITO and can be adopted in other stretchable and flexible devices.