Time-of-Flight Measurement of Hole Mobility in Aluminum (III) Complexes

We measured hole drift mobility in vacuum-deposited films of aluminum (III) complexes, tris (8-quinolinolato) aluminum (III) (Alq3), tris (8-phenanthridinolato) aluminum (III) (Alph3) and tris (4-methyl-8-quinolinolato) aluminum (III) (Almq3), using a time-of-flight technique. Hole transport was nondispersive for Alq3 and dispersive for Alph3 and Almq3. The hole mobilities of these aluminum complexes were of the order of 10-10–10-8 cm2/Vs and were largely dependent on the electric field.