<p>Although enhanced triboelectric output has been reported in ferroelectric polymers, the underlying mechanism remains unclear. Remnant polarization and piezoelectricity in poled ferroelectric polymers can be coupled with triboelectrification and electrostatic induction during physical contact. Here, we investigate the dominant mechanism responsible for the large triboelectric output of the ferroelectric polymer polyvinylidene fluoride (PVDF) through sequential non-contact, contact, and non-contact measurements. A systematic investigation of the charge outputs of unpoled, up-poled, and down-poled PVDF films, which exhibit very similar surface roughness and dielectric constants, reveals that the triboelectric charge outputs are strongly dependent on the relative polarization difference. It is greatest for contact between up-poled PVDF and down-poled PVDF, whereas it is smallest for contact between unpoled PVDF and unpoled PVDF. These results indicate that the surface potential difference, associated with the mutual energy level difference between the two surfaces, can be tuned by the remnant-polarization-induced electric field and plays a dominant role in governing the triboelectric output in ferroelectric polymers.</p>