Biaxially Prestrained Stretchable Electrodes Based on Ag/Organic Composite Film.

With the growing interest in wearable or stretchable electronics, research on stretchable electrodes has also been active. Generally, metal electrodes have high conductivity but very low stretchability, while organic electrodes have high stretchability but lower conductivity than metals. In this paper, metal/organic hybrid electrodes were fabricated on elastic poly(dimethylsiloxane) (PDMS) substrates to take advantage of the high conductivity of metals and the high stretchability of organic semiconductors. Additionally, by prestraining the PDMS substrate, the stretchability of the electrodes was further increased. However, the uniaxially prestrained electrodes produced compressive stresses in the direction perpendicular to the stretching direction due to Poisson's effect, resulting in many cracks. To solve this problem, biaxial prestrain was introduced to the PDMS substrate. The electrodes fabricated with uniaxial prestrain exhibited a structure with wrinkles aligned in one dimension, whereas the electrodes with biaxial prestrain displayed highly ordered, two-dimensional wrinkle patterns arranged on the electrode surface. The electrodes with biaxial prestrain maintained stable electrical performance even after 200 cycles of stretching at a strain of 50%, withstanding up to 130% strain. Furthermore, of all the poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS)-based electrodes reported so far, our electrode showed the lowest sheet resistance of 0.91 Ω/sq. The strategy of our study offers promising opportunities for integrated wearable devices.