Experimental Investigation of the Optical and Electrical Properties of Pristine Polyacenic Materials

Both electrical and optical characteristic have been studied for.polyacenic material prepared by pyrolysis of phenolformaldehyde resin. The experimental results indicate that the electrical conductivity of polyacenic material increases with the rise in pyrolytic temperature（T_p）. The sample prepared at T_p(=600℃) demonstrates that the behavior is governed by three-dimensionals-range-hopping （3D-VRH） mechanism at the temperature range 77K-100K. Both 0.052eV and 0.074eV acceptical energy levels （or energy band ） exist in this sample. Raman spectrum demonstrates that the grapitization structured aromatic rings increase with the rise of the pyrolytic temperature, which would give rise to the electrical conductivity. The pristine polyacenic material can not become narrow gap semiconductor even if the electrical conductivity of sample is larger than 10¹ S · cm^-1.