Influence of oxygen on band alignment at the organic/aluminum interface

The presence of adventitious oxygen is inevitable when organic/metal interf aces are formed by evaporation in high vacuum (10(-6) mbar.). In this lette r, we highlight the importance of this oxygen for band alignment, and hence , performance, in organic-based devices. The influence of controlled amount s of oxygen on band alignment in benzene/aluminum model cathode interfaces has been studied using ultraviolet photoemission in ultrahigh vacuum. We sh ow that even small amounts of oxygen significantly lower the aluminum work function with concomitant improvement in band alignment. (C) 2000 American Institute of Physics. [S0003-6951(00)02534-1].