Charge injection and resulting charge distributions in commercially available polymers

摘要

The distribution of charge injected into Lexan and Lucite has been studied using an electrostatic voltmeter. The samples were 16 cm diameter disks cut from 3.2 mm thick commercially available sheets. Aluminum electrodes were vacuum evaporated onto vacuum dried samples. One electrode entirely covered one side of the disk shaped sample. The electrode on the other side was a disk, centered on the sample and was either 2.54 cm or 5.08 cm in diameter. This allows a comparison of the relative importance of injection from the perimeter and the area of the electrode. The samples-were then placed in a vacuum chamber capable of 1 × 10?6 Torr. Voltages of 500 and 3000 Vdc were connected for periods of hours to days and the resulting currents recorded. The samples were then scanned, in situ, using an electrostatic voltmeter probe. Two dimensional maps of the surface voltage reveal charge distributions which are nonuniform over centimeter distances including alternations in sign. This suggests an electron-hole charge transport mechanism.