BLUE EMISSION FROM POLYMER LIGHT-EMITTING-DIODES USING NONCONJUGATED POLYMER BLENDS WITH AIR-STABLE ELECTRODES

By dispersing a non-conjugated luminescent polymer and an electron-tra nsporting material, iphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), into a hole-transporting polymer, poly(9-vinylcarbazole) (PVK) , we have achieved improved efficiencies for blue light-emitting diode s (LEDs) fabricated with a copolyester (CPE) containing isolated 1,2-d inaphthylethene units. Quantum efficiencies of the LEDs with the solid dispersion of CPE and PBD in PVK as electroluminescent layer and indi um as the electron injection electrodes are about 0.1% photons per ele ctron, better by factor of 10(2) than similar devices made with only t he CPE. The LEDs turn on at about 30 V and have a peak emission wavele ngth in the blue at 485 nm.