Bond cutting in Cs-doped tris(8-hydroxyquinoline) aluminium

A series of Cs 4d and Al 2p spectra associated with valence-band and cut-off spectra have been used to characterize the interaction between caesium and tris(8-hydroxyquinoline) aluminium (Alq₃) molecules in a Cs-doped Alq₃ layer. The Cs 4d and Al 2p spectra were tuned to be very surface sensitive by selecting a photon energy of 120 eV at the National Synchrotron Radiation Research Center, Taiwan. A critical Cs concentration exists, above which a new Al 2p signal appears next to the Al 2p peak of Alq₃ in the lower binding-energy side. The Al 2p signal was analyzed and assigned as being contributed from a mixture of Alq₂, Alq and Al. Experimental data supported the observation that bond cutting of Alq₃ by the doped Cs atoms occurred at high Cs doping concentration.