Thermomechanical pressing and immediate quenching: enhanced piezoelectricity and transparency in piezoelectric nanofibers

) compared to the nanofibers. In addition, this poling-free process increases film transparency, significantly reduces haze, and greatly improves mechanical robustness and stiffness. These improvements are attributed to the flash crystallization effect induced by hot pressing and immediate cooling, which elongates the crystal chains, increases the lamellar dimensions, and expands the oriented amorphous fraction regions. As a result, a well-organized semi-crystalline structure is formed over the expanded regions. Our method is simple and allows precise control over the crystal structure, which promises to produce transparent piezoelectric films ideal for force sensing and energy harvesting applications.