Blue organic light-emitting diodes based on spiro[fluorene-indeno]pyridine derivatives

초록

We designed and synthesized two blue fluorescent materials based on spiro[9H-fluorene-9, 5-[5H] indeno[1, 2-b] pyridine via Buchwald-Hartwig amination and Suzuki coupling reaction. To characterize their electroluminescent properties, multilayered organic light emitting diodes (OLEDs) were fabricated with the following device structures: ITO(180nm)/2-TNATA(60nm)/NPB(20nm)/,-ADN: 3, 5, or 10wt% blue dopants (30nm)/Bphen(30nm)/Liq(2nm)/Al(100nm). All the devices showed blue emissions with high electroluminescent efficiencies. Particularly, a device using 7-((4-(N,N-diphenyl)-styryl)-4-phenyl)-spiro[9H-fluorene-9, 5-[5H] indeno[1, 2-b] pyridine] as a dopant material with 10wt% doping concentration exhibited highly efficient blue emission with an external quantum efficiency of 4.46% at 20 mA/cm(2) and the CIE coordinates of (0.18, 0.30) at 1000 cd/m(2). In this device, the twisted structural feature of emitter originated from spiro-type core prevented self-quenching and lead to the improved efficiencies even at high doping concentration in the device.

키워드