EXCITON AND ELECTRON TRAPS ON STRUCTURAL DEFECTS IN MOLECULAR-CRYSTALS WITH DIPOLAR MOLECULES

The depths of exciton and electron traps arising due to the presence of structural defects in organic crystals consisting of dipolar molecules are calculated. In the model studied a structural defect appears if a molecule is rotated by 180 degrees around the long axis as compared to the bulk molecules. The contribution of the electrostatic interaction to the depth of the trap state on such a defect is studied in detail. For crystals consisting of molecules which have a large dipole moment in the ground state and adopting large values in the excited state this contribution may be dominant. The calculations are carried out for triplet excitons and electrons in benzophenone crystal.