Bond cutting in K-doped tris(8-hydroxyquinoline) aluminium.
A series of Al 2p, K 2p, O 1s and N 1s core-level spectra have been used to characterize the interaction between potassium (K) and tris(8-hydroxyquinoline) aluminium (Alq(3)) molecules in the K-doped Alq(3) layer. All core-level spectra were tuned to be very surface sensitive in selecting various photon energies provided by the wide-range beamline at the National Synchrotron Radiation Research Center, Taiwan. A critical K concentration (x = 2.4) exists in the K-doped Alq(3) layer, below which the K-doped atoms generate a strained environment near the O and N atoms within 8-quinolinoline ligands. This creates new O 1s and N 1s components on the lower binding-energy side. Above the critical K coverage, the K-doped atoms attach the O atoms in the Al-O-C bonds next to the phenoxide ring and replace Al-O-C bonds by forming K-O-C bonds. An Alq(3) molecule is disassembled into Alq(2) and Kq by bond cutting and bond formation. The Alq(2) molecule can be further dissociated into Alq, or even Al, through subsequent formations of Kq.
Lee
Hsin Han
HH
Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
Hwang
Jennchang
J
Pi
Tun Wen
TW