Study of ion bombardment effect for Alq3 films

This paper investigated the blue shift of photoluminescence and the changes of surface morphology of Alq3 films by ionic argon plasma bombardment. Plasma with different conditions was applied to bombard thin Alq3 films, modifying both the physical and chemical properties of the films. After characterizing Alq3 films treated with different RF power by XPS, PL and AFM, we proposed the mechanisms to explain the absence of PL blue shift and chemical shift after the films were exposed in the air for more than 3 h. Experimental results showed that molecular structure damages would affect the bandgap of Alq3, leading to the blue shift effect. XPS results also showed that binding energy shifts are caused by enriched oxygen covalent bonds formed inside the films after plasma treatment. Also, surface roughness improves as RF power is increased.