PHOTOCONDUCTION IN VACUUM-EVAPORATED FILMS OF PHENOTHIAZINE

Steady-state photoconduction characteristics have been measured for th e system vacuum-evaporated film of phenothiazine contained between alu minum semitransparent electrodes. Three spectral regions of the action spectrum are distinguished: (i) (200-300) nm with near-surface charge generation and its subsequent injection into the bulk; (ii) (300-370) nm dominated by die surface injected current; and (iii) > 370 nm char acterized by a superposition of the surface and bulk generated carrier s. A weak feature between 400 and 420 nm corresponds to the low energy charge-transfer excitons suggested previously to yield a large photoc onduction peak at is-approximately-equal-to 410 nm in phenothiazine si ngle crystal.