PNNL

Abstract

Despite the promise of silk-based devices, the inherent disorder of native silk limits performance. Here we report highly ordered two-dimensional (2D) silk fibroin (SF) films grown epitaxially on van der Waals (vdW) substrates. Using atomic force microscopy, infrared nano-spectroscopy, and molecular dynamics, we show that the films consist of lamellae of SF molecules that exhibit the same secondary structure as the nano-crystallites of native silk. Increasing the SF concentration results in multilayers that grow either by direct assembly of SF molecules into the lamellae or, at high concentrations, along a two-step pathway beginning with a disordered monolayer that then crystallizes. Kelvin probe measurements show that these films substantially alter the surface potential; thus, they provide a platform for silk-based electronics on vdW solids.