Effect of dipolar arrays on the localization of charge carriers inmolecular materials |
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Authors: | Sworakowski J |
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Affiliation: | Inst. of Phys. & Theor. Chem., Tech. Univ. Wroclaw; |
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Abstract: | The paper presents results of calculations of the depth and distribution of local states for charge carriers created by polar impurities in a model molecular material. Equations resulting from the electrostatic model due to Lyons have been employed in the calculations. The presence of polar species in a non-polar molecular material locally modifies the polarization energy, thus creating local states (traps) on neighboring molecules. Calculations performed for an isolated dipolar defect show that traps as deep as ~0.4 eV to ~0.5 eV can result in such a way, their depths and cross-sections depending on the dipole moment of the guest molecule. Results of similar calculations carried out for arrays of spatially connected dipoles indicate that local states of a considerable density may be created, modifying the density-of-states function, and hence influencing the effective mobility of charge carriers |
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