Shape‐Engineerable Silk Fibroin Papers for Ideal Substrate Alternatives of Plastic Electronics

Abstract Plastic‐based electronics fill the gaps in conventional rigid silicon‐based devices toward the applications in soft interfaces. However, people in the future should also consider their potential environmental impact if tons of non‐degradable plastics are applied. Silk fibroin is a superior substrate alternative for the development of “green” electronics; whereas, the brittleness of silk films is still a major limitation impeding their practical use. Different from the widely reported polyphasic composite approaches, here a trace‐ion‐assisted plasticization strategy is developed, and shape‐engineerable pure silk fibroin paper (PSFP) is prepared for the first time, which can be engraved and crumpled like a sheet of paper in the dry state. The PSFPs exhibit higher tensile fracture energy (14.4 ± 4 kJ m −2 ) than any typical plastic‐electronic‐substrates as far as it is known. The intrinsic brittleness of pure silk films is overcome, and the PSFP can be easily engineered to form periodic meshes, electronic prototypes, and kirigami‐based devices, which are beyond the reported regenerated silk films or silk composite films. Moreover, the scrape coating method employed here is simple, highly repeatable, and suitable for scaled production of low‐cost PSFP continuously. Collectively, the PSFP is generalizable to various shapes and devices, represents an ideal substrate alternative to plastic electronics.