Organic light emitting devices containing a highly substituted isoindole or polyisoindole

A highly substituted and fluorescent Isoindole has been used in a bilayer type of organic electroluminescent device with either PVK or Alq 3. The best results (maximum luminance >6000 cd/m 2, apparent quantum yield at max luminance of 1.1%, and a low threshold voltage of 4 V) are obtained for the combination: anode/Isoindole/Alq 3/cathode. These devices are characterized by the Alq 3 electroluminescent spectrum. The role of Isoindole is that of a hole transport material. This is in agreement with the reversible character of Isoindole electrochemical oxidation and the stability of the Isoindole cation radical in solution. Lower maximum luminances (∼30 cd/m 2) are obtained when Isoindole is replaced with Polyisoindole, a polymer containing the Isoindole in its backbone.