STUDIES ON THE TEMPERATURE-DEPENDENT PHOSPHORESCENCE OF POLY(N-VINYLCARBAZOLE)

Phosphorescence lifetimes and spectra of solid films of poly(N-vinylcarbazole) (PVCA) have been obtained at temperatures between 77 and 298 K. The presence of two trapped triplet species is confirmed and their energies are found to be 1.97 × 104 and 2.12 × 104 cm-1. At 77 K the deep trap has a lifetime of 1.7 ± 0.08 s and the shallow trap 7.7 ± 0.6 s. Activation energies for the decay of these two triplets are 1000 cm-1 for the deep trap and 200 cm-1 for the shallow trap. Assuming these activation energies represent trap depths below the mobile triplet level, one finds that the energy of mobile triplets is ∼2.1 × 104 cm-1 which places it about 2000 cm-1 below the isolated carbazolyl triplet. Effects of solvent and techniques employed in film formation are found to have minor influences on lifetimes or spectra. © 1979 American Chemical Society.