The properties of space charge (homocharge) and dipoles (heterocharge) in various electrets have been in the focus of interest since the investigations of B. Gross on carnauba wax. In this article we present a review on the role and the interaction of charges and dipoles in the polymeric electret polyvinylidenefluoride (PVDF). It covers the importance of charge injection for the orientation of the dipoles at low fields as well as the role of charge trapping for the stabilization of the polarization. Investigations of the thermal stability of the polarization and the charge balance are leading to a detailed analysis of the depth and localization of the charge traps. Furthermore, it was possible to identify the space charge as ions created electrochemically during the poling process.
