Probing contact electrification processes from interfacial charge transfer to bulk transport in semicrystalline polymers.

Contact electrification (CE), a ubiquitous phenomenon enabling mechanical-driven power generation, has emerged as a promising approach for sustainable energy conversion. However, due to the lack of quantitative characterization tools and well-defined correlations with material properties, the dynamic processes and underlying mechanisms of contact-induced mechano-electric conversion (MEC) remain poorly understood. Herein, we develop a standardized multiscale quantitative method for characterizing contact-induced charges, enabling precise measurement and in-situ observation of MEC. Furthermore, we systematically investigate how key properties of common semicrystalline polymers (such as band structure and aggregation state) govern MEC behaviors, establishing an intrinsic relationship between material properties and MEC performance. Building up this, we propose a coherent two-step CE model involving interfacial charge transfer followed by bulk charge transport, which describes the complete lifecycle of contact-induced charges from generation to collection. We further reveal that differences in interfacial energy-level alignment serve as the fundamental driving force for electron transfer from donors to acceptors, while injected charge carriers are transported via a hopping conduction mechanism between localized state traps. This study establishes a paradigm for CE research, deepening the fundamental understanding of contact-induced MEC and laying a foundation for the design of next-generation high-performance polymer dielectrics.