Patterned surface dipole layers for high-contrast electroluminescent displays

A straightforward and general method to pattern organic light-emitting devi ces is demonstrated that entirely obviates the need for patterning either t he organic electroactive material or the electrodes. The technique takes ad vantage of elastomeric stamp patterning of indium tin oxide electrodes usin g simple surface chemistry. A base reacts with the oxide surface to form a double ionic layer that drastically inhibits the ability to inject positive charge carriers from the oxide anode. We have achieved remarkably high con trast ratios (> 10(5)) in the technologically-useful hybrid triphenyl diami ne and 8-(hydroxyquinoline) aluminum light-emitting diode. Furthermore, the adsorbed double layer shows excellent stability even when the device is dr iven beyond the damage threshold. (C) 1999 American Institute of Physics. [ S0003-6951(99)04238-2].