Photoemission of Holes and Valence Band Structure in Anthracene

Recent measurements of the Hall effect for volume-generated holes in anthracene and analysis of the differences between Hall and drift mobility values for electrons and holes suggest that both carriers move in a two-band system; a narrow band where the mobility is of the order of 1 cm2v−1 sec−1 separated from a much wider band with high mobility by an energy of the order of 0.05 eV.(1) For electrons, the existence of wider bands has been well established by internal photoemission.(2,3) The conduction band system consists of a narrow band, less than 0.33 eV wide, separated by less than 0.05 eV from a higher band 0.3 eV wide.(3)