Organic light emitting diodes using an aryl-substituted isobenzofuran as electron transport material

B1553, a functionalized derivative of isobenzofuran is highly fluorescent in solution in toluene but also in the solid state, where its emission peaks at 508 nm. B1553 is able to transport electrons and holes but is, however, a better electron transport (ET) than a hole transport material. It is possible to use B1553, vacuum sublimed or spin-coated from a solid solution in a host polymer, as an ET layer with a first spin-coated hole transport layer. The performance of these devices is improved when a hole-blocking layer is added between B1553 and the cathode. In that case, a maximum luminance of 1100 cd/m2 is obtained at 400 mA/cm2.