All‐Organic Flexible Piezoelectric Self‐Powered Sensors Through Gradient Engineering of P(VDF‐TrFE) Fibers and PEDOT:PSS

Electrospinning-derived piezoelectric polymer P(VDF-TrFE) fibers represent promising materials for piezoelectric self-powered sensors in wearable and biomedical applications, attributed to their lightweight nature, flexibility, and superior piezoelectric properties. However, integrating effective electrodes with P(VDF-TrFE) fibers remains challenging. Metal electrodes often fail to maintain stable contact on complex fiber surfaces, while conductive polymer electrodes face limitations in conductivity and chemical compatibility with P(VDF-TrFE). To address these issues, a composition-gradient interface is developed between organic conducting polymer, PEDOT:PSS electrodes, and P(VDF-TrFE) fibers, resulting in high-efficiency, all-organic piezoelectric self-powered sensors. This interface, achieved through carefully selecting DMSO as a doping solvent, creates a mechanically robust structure that enhances compatibility between PEDOT:PSS and P(VDF-TrFE). The optimized gradient electrode exhibits a sheet resistance of 3.5 Ω sq^-1, approximately three orders of magnitude lower than that of pristine PEDOT:PSS (5800 Ω sq^-1). The sensors not only demonstrate sensing voltage performance comparable to metal-electrode sensors but also exhibit remarkable stability under various deformations along with reliable adhesion to curved surfaces. The findings highlight the potential of composition-gradient interfaces in enhancing electrical contact and mechanical stability in organic devices, providing a versatile approach for improving the performance of diverse organic electronic systems and supporting scalability for large-area applications.