Neat Alq3 thin film and metal/Alq3 interfaces studied by NEXAFS spectroscopy

The spectral changes at the metal/Alq3 and Al/LiF/Alq3 interface were found to depend on the metal. By the comparison with the theoretical simulations based on the 1:1 metal-Alq3 complex, we found that the electron transfer and orbital overlap occur at the interfaces of K/Alq3 and Li/Alq3, while the observed changes at the Ca/Alq3 and Al/Alq3 interfaces could not be understood by the simulated results. At the LiF/Alq3 interface, we observed the spectral changes which may result from some chemical interaction. Some of the spectral changes at Al/LiF/Alq3 interface differ from those of Al/Alq3 interface, indicating chemical interaction specific for the co-existence of Al, LiF, and Alq3.