Field and temperature dependent recombination in anthracene.

The quantum efficiency of photoconductivity in anthracene depends on electric field and temperature. Analysis of these results strongly suggests that the generation of free holes and electrons can be described by a model in which, following the initial ionization, most electron-hole pairs are thermalized while still bound by their mutual Coulomb field. The electron and hole may then either recombine or separate as free carriers as they diffuse subject to their mutual Coulomb field and the applied field. Interpreted in the light of this model, the dependence of free carrier quantum yield on temperature and photon energy indicates that the primary ionization process involves energy relaxation and autoionization rather than direct ionization.