Abstract:
Photophysical and electrochemical properties of 7,16-dihydroheptacenes (1-3) were investigated in detail. Although their HOMO-LUMO gaps are higher than 3 eV, the organic light-emitting diodes containing 1 as the emitting dopant showed green electroluminescence (λmax ∼ 515 and 550 nm) even at a concentration of the dopant as low as 1percent. The green electroluminescence of 1 appears to be originating from an electromeric state (an intermolecular ion pair). The maximum brightness of 190 cd-m2 was observed at a current density of 34 mA-cm2 at operating voltage of 19 V for the device containing 1percent 1, and overall performance of the devices decreased with an increase in the doping concentration of 1. © 2007 Elsevier B.V. All rights reserved.