Insight into the role of functional groups on the mechanical, piezoelectric and electrical properties of an individual reduced graphene oxide wrinkle

This work aims to correlate the structural and physical properties (mechanical, piezoelectric, electrical) of individual graphene oxide (GO) wrinkle using advanced modes of atomic force microscopy (AFM). The high stiffness value of GO wrinkles in phase detection microscopy (PDM) indicates the wrinkle has a high sp 2 /sp 3 carbon ratio and is attributed to the strain induced by the curvature of the wrinkle, which decreases the stability of functional groups. Piezo force microscopy (PFM) measurements demonstrated the strain induced and non-switchable piezoresponse on the wrinkle structure. Functional groups attached plane GO region shows switchable polarization with a piezoresponse of 6 pm/V. The ripple type wrinkles have low strain and high conductance due to their small height and two-dimensional (2D) nature. Above 5 nm height, standing collapsed and folded wrinkles transform into a three-dimensional (3D) structure that facilitates tunneling and anisotropy in electron transport. These findings show that by controlling the functional group concentration, strain, and height of an individual GO wrinkle, one can engineer the wrinkles on the GO structure to meet the needs of practical applications. • Effect of functional groups on the physical properties of a graphene oxide (GO) wrinkle was investigated. • Stability of the attached functional groups decreased on the wrinkle structure due to curvature of the wrinkle. • The wrinkle possesses high mechanical and electrical conductance than the plane GO region. • The charge transport across the ripple type wrinkle is 3 times higher than the standing collapsed and folded wrinkles. • A d 33 value of 6 pm/V was measured from the plane GO region.