Blue organic light-emitting diodes based on spiro[fluorene-indeno]pyridine derivatives. (2nd January 2018)

• Record Type: Journal Article
• Authors: Jeong, Sujin; Kim, Changmin; Kim, Se Hyun; Kim, Dong Young; Lee, Song Eun; Kim, Young Kwan; Yoon, Seung Soo
• Is Part Of: Molecular crystals and liquid crystals. Volume 660(2018)
• Page Start: 24
• Page End: 32
• Publication Date: 2018-01-02
• Subjects: Blue OLED -- electroluminescence -- fluorescence -- spiro [fluoreneindeno] pyridine; Molecular crystals -- Periodicals; Liquid crystals -- Periodicals; Liquid crystals; Molecular crystals; Periodicals; 548
• DOI: 10.1080/15421406.2018.1452867
• Languages: English
• ISSNs: 1542-1406

Abstract

ABSTRACT: 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(180 nm)/2-TNATA(60 nm)/NPB(20 nm)/α, β-ADN: 3, 5, or 10 wt% blue dopants (30 nm)/Bphen(30 nm)/Liq(2 nm)/Al(100 nm). 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 10 wt% 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.