Electric-field and temperature dependence of the hole mobility in poly(p-phenylene vinylene)

The current-voltage characteristics of poly (dialkoxy p-phenylene vinylene) -based hole-only devices are measured as a function of temperature. The hole current is space-charge limited, which provides a direct measurement of the hole mobility ₏ as a function of electric field E and temperature. The hole mobility exhibits a field dependence ln ₏E as has also been observed from time-of-flight experiments in many molecularly doped polymers and amorphous glasses. For the zero-field hole mobility an activation energy of 0. 48 eV is obtained. The combination of a field-dependent mobility and space-charge effects provides a consistent description of the hole conduction in conjugated polymer films as a function of voltage, temperature, and layer thickness.