Studies of Organic Semiconductors for 40 Years—I The Mobile π-Electron—40 Years on

The earliest studies concerned photoelectric emission of negative charges from dyestuff solutions,1,2 and anthracene layers.3 The negative charges were identified as electrons,4 then in 1911 Goldmann and Kalandyk5 separated photoconduction from photoelectric emission, observing it in anthracene under U.V. irradiation, while Pauli6 and Volmer7 studied photoconduction in anthracene in the visible. Petrikaln8 discussed gas effects on visible light photoconduction in dyestuffs, Koenigsberg and Schilling9 studied dark conduction in anthracene, naphthalene and alizarine and also deduced the formula linking specific conductivity a with absolute temperature T, [sgrave] = [sgrave]0,exp(-Eact/kT). Further dark conduction studies were carried out by Rabinowitsch.