Study on trap states in photorefractive polymer of polyvinylcarbazole

The measurement of thermally stimulated current (TSC) spectrum was completed in photorefractive polymer of polyvinylcarbazole (PVK). The active energy of the thermally stimulated relaxation process in PVK was obtained. The results show that there are two peaks in TSC spectrum of PVK, the low-temperature peak at 338 K has 0.6 eV active energy, while the high-temperature peak at 117 K has the active energy ranging from 0.53 to 1.00 eV. and the distribution was similar to Gauss law with a 0.77 eV maximum. The maximum of trap density is 5.7 × 10¹⁸ cm^-3. Meanwhile, it is proved that the low-temperature originates from the reorientation relaxation of carbazole group and the high-temperature peak originates from the thermo-release of holes in the trap states.