AC DIELECTRIC-SPECTROSCOPY OF OXONOL DYES - A VERSATILE PROBE FOR THE EXAMINATION OF CHARGE IN ORGANIC SEMICONDUCTORS

Low-frequency a.c. dielectric spectroscopy has been used to probe contact effects on, and the dielectric behaviour of, a series of structurally related organic dyes (hydroxypyridone trimethine oxonol salts) as compressed powders. The technique reveals contributions from dipolar relaxation, small-particle migration, and electronic conductivity depending on the nature of the counter cation. In general, whilst changing contacts to the samples modified the relaxation rate, neither the spectral form nor the magnitude of the a.c. response were affected.