Fig. 4
Stretchability modeling of Si nanomeshes. a Sheet resistance of a bilayer nanomesh film with 33.7% fill factor as a function of tensile strain. BT means before transfer. SEM images (inset) of zero, 14 and 28% strain states, showing the microscale stretching behavior of the nanomeshes. The scale bar is 1 μm. b Change in sheet resistance versus stretching cycles (up to 1000 cycles) of a bilayer nanomesh film (33.7% fill factor). c Schematic mechanics model of the PI/Si bilayer structure on an infinitely thick and soft PDMS substrate. An applied strain extends the bottom of the PI layer from the original length of l0 to the deformed length of l0εapplied. d The normalized maximum strain εmax/εmax0 in the Si layer vs the normalized PI layer thickness, as predicted by FEA (dots) and Eq. (3) (solid line). e FEA simulation of stress distribution in a PI/Si nanomesh film at 10%, 20%, 30%, and 40% strain state, respectively
