As a result of study on the charge formation using space charge profiling technique, it was found that the residual electron density decreases with increasing poly-caprolactone (PCL) content in polycarbonate (PC)/poly(styrene-co-acrylonitrile)(SAN)/polycaprolactone (PCL) blends. This feature was attributed that the PCL encourages the chemical interaction between PC and SAN at their interphase interface through which the electrons could move freely. It is speculated that the PCL acts as a bridge for electrons to hop. However, the crystallization of PCL and PCL-induced crystallization of PC enhances the trapping of electrons at the interface between amorphous and crystalline phases and thus the residual electron density increases at higher PCL content, i.e., higher than 20% of PCL in this particular case.