Figure 4. Fracture images and a thickness–ROC map for transparent flexible electrode films under bending.

(a) SEM images showing brittle Ag NWs with diameters large than 40 nm after bending at various strains under same ex-situ condition at the substrate thickness of 150 μm. (b) The straight strain lines showing a linear relationship between substrate thickness and ROC correspond to the intrinsic fracture strains of brittle Ag NWs and ITOs. The dashed and dotted lines in the thickness–ROC curve presents the intrinsic fracture strains for ductile Ag NWs with diameters below 7.5 nm²⁷,²⁸ and 25 nm, respectively.