A Universal Orientation-Engineering Strategy for Enhancing Mechano-Electric Conversion Performance in Semi-Crystalline Biopolymers.

High-charge-density triboelectric materials are the key to developing high-performance triboelectric nanogenerators. However, most semi-crystalline biopolymers exhibit low triboelectric output performance due to the limitations in their intrinsic structure and physicochemical properties. Herein, orientation-regulated silk fibroin nanofibers (SFNs) with phase transition polarization and enhanced carrier migration are developed through high-voltage and high-speed synergistic electrospinning technology. To analyze the molecular and aggregation structural changes of SFNs during high-voltage electric fields and stress-induced orientation processes, a multiscale structural evolutionary model is constructed from microscopic molecular chains to mesoscopic aggregation structures, and then to macroscopic fiber arrangements. It is found that as the orientation coefficient increases, the molecular conformation shifts from disordered α-helices to ordered stacked β-sheets. The aggregated molecular chains gradually slip, recombine, and arrange in an orderly manner along the direction of the stress field, which contributes to regulating the charge capture and carrier migration properties. The orientation-regulated SFNs significantly enhance the interfacial charge transfer and bulk charge transport capacity, thereby greatly improving the triboelectric performance. This work not only provides new insights into the mechano-electric conversion mechanisms of semi-crystalline biopolymers but also offers guidance for the design of high-charge-density triboelectric materials.