Smart windows prepared from Bombyx mori silk

Abstract

We introduce a bio-inspired strategy for the synthesis of green polymer electrolytes (PEs) which relies on the use of silk fibroin (SF). The two series of PEs prepared, doped with lithium bis(trifluoromethanesulfonyl)imide (SF@LiTFSI) or lithium tetrafluoroborate (SF@LiBF4) and incorporating glycerol, exhibited outstanding filmogenic properties, very high transparency and suitable adhesion to glass substrates. Despite their poor ionic conductivity, the SF-based films (SF@) were employed in the construction of glass/ITO/WO3/SF@/CeO2-TiO2/ITO/glass electrochromic devices displaying an optical modulation up to 5.5 % at 633 nm, switching speed of ca. 15 s, stability up to 5160 cycles, and coloration efficiency up to −53.1 m2 C−1 . This work, in which we provide the proof-of-concept, paves the way for new design approaches for silk-based materials, enlarging the range of applications of SF to the energy field.