Figure 5: Characterization of the mechanical properties by nano-indentation and nano scratch test.
From: Non-volatile organic memory with sub-millimetre bending radius
(a) Representative loading and unloading curves in nano-indentation tests. (b) An instrumented testing hardness, HIT, and an instrumented testing elastic modulus, EIT for PVDF-TrFE, QQT(CN)4 coating on PVDF-TrFE and P3HT coating on PVDF-TrFE. Each bar is an average value with s.d. for five indentation tests. (c) The ratio of elastic energy (Eelast) to the total energy (Etotal) for PVDF-TrFE, QQT(CN)4 coating on PVDF-TrFE and P3HT coating on PVDF-TrFE. Each bar is an average value with s.d. for five indentation tests. (d) Schematic of bending stress distribution of a two-layered film under the condition of elastic deformation with E2=E1, elastic deformation with E2>E1, and elasto-plastic deformation with E2>E1 at the same radius of curvature ρ (centroid of geometry (dot-dashed line), neutral axis, N.A. (dotted line), Young’s modulus (E1) and thickness (t1) of substrate, and Young’s modulus (E2) and thickness (t2) of top layer). (e) Schematic of nano scratch test with a ramp loading and representative optical images along the scratches after tests for P3HT coating on PVDF-TrFE and QQT(CN)4 coating on PVDF-TrFE. A rectangular box in the image indicates a region where a critical load is defined. Scale bar, 50 μm. (f) Critical loads for P3HT/PVDF-TrFE and QQT(CN)4/PVDF-TrFE bilayers. Each bar is an average value with s.d. for five nano scratch tests. (g) The magnified SEM images taken at the region of the rectangular box in (e). As denoted by arrows, semiconductor coatings (P3HT and QQT(CN)4) and the underlying layer of PVDF-TrFE can be readily identified in the images. Scale bar, 300 nm.
