Electric field-assisted bipolar charge spouting in organic thin-film diodes

We propose a concept of electric field-assisted bipolar charge spouting in organic solid films, and experimentally verify this concept based on device characteristics of organic thin-film diodes. Three organic thin-film diodes, indium-tin oxide (ITO)/N,N-'-diphenyl-N,N-'-bis(3-methylphenyl)-1,1(')-biphenyl-4,4(')-diamine (TPD)/tris(8-quinolinolato)alminum(III) (Alq(3))/Al (conventional light-emitting diode), ITO/Alq(3)/TPD/Al (inverted-stack diode), and ITO/Alq(3)/Mg-doped Alq(3)/V2O5/TPD/Al (inverted-stack diode with carrier spouting zone), are prepared and their diode characteristics are observed. In the second diode, essentially no current flow is found when the ITO electrode is biased positive. On the other hand, large current flow is observed in the third diode, indicating the occurrence of charge carrier spouting from the charge separation zone composed of Mg-doped Alq(3) and V2O5. (C) 2004 American Institute of Physics.