Details

Autor(en) / Beteiligte

• CHEN, Hsiao-Fan
• YANG, Shang-Jung
• TSAI, Zhen-Han
• HUNG, Wen-Yi
• WANG, Ting-Chih
• WONG, Ken-Tsung

Titel

1,3,5-Triazine derivatives as new electron transport―type host materials for highly efficient green phosphorescent OLEDs

Ist Teil von

• Journal of materials chemistry, 2009-01, Vol.19 (43), p.8112-8118

Ort / Verlag

Cambridge: Royal Society of Chemistry

Erscheinungsjahr

2009

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We have synthesized three star-shaped 1,3,5-triazine derivatives--2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (T2T), 2,4,6-tris(triphenyl-3-yl)-1,3,5-triazine (T3T), and 2,4,6-tris(9,9'-spirobifluorene-2-yl)-1,3,5-triazine (TST)--as new electron transport (ET)-type host materials for green phosphorescent organic light-emitting devices. The morphological, thermal, and photophysical properties and the electron mobilities of these ET-type host materials are influenced by the nature of the aryl substituents attached to the triazene core. The meta-meta linkage between the 1,3,5-triazine core and the peripheral aryl moieties in T2T and T3T limited the effective extension of their P conjugation, leading to high triplet energies of 2.80 and 2.69 eV, respectively. Time-of-flight mobility measurements revealed the good electron mobilities for these compounds (each > 10(-4) cm(2) V(-1) s(-1)), following the order T3T > TST > T2T. The device incorporating T2T as the host, doped with (PPy)(2)Ir(acac) and 1,3,5-tris(N-phenylbenzimidizol-2-yl)benzene (TBPI) as the ET layer, achieved a high external quantum efficiency (E(ext)) of 17.5% and a power efficiency (E(p)) of 59.0 lm W(-1). For the same device configuration, the T3T-based device provided values of E(ext) and E(p) of 14.4% and 50.6 lm W(-1), respectively; the TST-based device provided values of 5.1% and 12.3 lm W(-1), respectively. We ascribe the superior performance of the T2T-based devices to balanced charge recombination; we ascribe the poor efficiencies of the TST-based devices to its relatively low triplet energy (2.54 eV), which did not allow efficient confinement of the triplet excitons on the green phosphorescent emitter (PPy)(2)Ir(acac).