ESR study of alkali-doped polyacenic semiconductor (PAS) materials prepared by thermal decomposition of azides

The alkali-doped polyacenic semiconductor (PAS) materials have been prepared by thermal decomposition of alkali azides (AN(3), where A=Li, Na, K and Rb) in vacuo, and their electronic properties have been studied based on the electron spin resonance (ESR) spectral measurements as functions of atomic number (Z) of the dopant metal and of temperature (T) in the range 2-300 K. From the ESR spectrum, it was confirmed that the PAS material was successfully doped by a certain amount of alkali metal. The value of ESR linewidth was found to increase with Z and to linearly decrease with decreasing T. This behavior strongly suggests that conduction electrons generated by the doping have some probability to locate on the dopant metal atom and that such a location is probably suppressed at low temperatures in a rather uniform manner irrespective of metal species. (C) 1997 Elsevier Science Ltd.