Blue organic light-emitting diode using 1,4-bis(1,1-diphenyl-2-ethenyl)benzene as an emitter

We report on the properties of 1,4-bis(1,1-diphenyl-2-ethenyl)benzene (PEB) as the active material for blue electroluminescent diodes. The diodes are fabricated by spin-coating of a single layer of PEB blended in a polystyrene matrix. We discuss the optimum solvent for this spin-coating process. The anode is indium–tin oxide, the cathode is evaporated aluminum. The external quantum efficiency of this simple blue diode with air-stable cathode is 0.25% at a current density of 28 mA cm−2. The two main peaks are at 455 and 480 nm. Taking into account the eye sensitivity, the diodeʹs efficiency is about 1.2 lm/A, which for perpendicular view, corresponds to 0.4 cd/A and 0.08 lm/W. We, furthermore, have measured transient photoluminescence and electroluminescent spectra, which reveal the appearance of peaks in the diode spectrum delayed by a few hundred milliseconds compared to the main peaks.