Swift heavy ion irradiation-induced modifications of tris-(8-hydroxyquinoline)aluminum thin films

Tris-(8-hydroxyquinoline)aluminum (Alq(3)), one of the most widely used light emitting and electron transport materials in organic luminescent devices, has been synthesized. Alq(3) thin films have been deposited by a thermal evaporation process on glass substrates. The effect of swift heavy ion (SHI) irradiation using 40 MeV Li3+ on the Alq(3) thin films has been studied by UV-visible, infrared, photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectroscopy. From TRPL studies, it is found that the PL of Alq(3) thin films arises from two species corresponding to its two geometrical isomers, namely facial and meridional having two different life times. It is also confirmed that the PL and lifetimes of excitons decrease with the increase of ion fluences of SHI of 40 MeV Li3+, indicating a transfer of exciton energy to unstable cationic Alq(3) species generated by SHI irradiation.