Electrical Properties of Copper Phathalocyanine at High Pressure

Publisher Website
Google Scholar
Abstract
The electrical properties of copper phthalocyanine were studied over a pressure range extending to 60 000 bars. Discontinuities of the energy gap, thermoelectric power, and resistance indicate the presence of two new phases at high pressure. At 1 atmosphere the activation energy is 0.85 eV; from about 2 to 30 kbar the energy varies between 0.45 and 0.35 eV; after rising to 0.55 eV at 30 kbar, it decreases continuously to 0.50 eV at 60 kbar. At 30 kbar, as pressure is increased, the thermolectric energy reverses sign, going from +0.3 to -0.3 eV, while the pre-exponential factor in the conductivity expression increases by a factor of 10. The results are analyzed in terms of an energy-band model with deep-lying impurity levels. It is found that at high pressures the activation energy is a direct measure of the energy gap. The 30-kbar transformation is accompanied by order-of-magnitude changes in the carrier mobilities and state densities, suggesting that marked changes in the energy-band structure have occurred. Tight-binding calculations indicate that these changes are due to orientation effects.

This publication has 10 references indexed in Scilit: