Fluorene/tridurylborane hybrids as solution-processible hosts for phosphorescent organic light-emitting diodes

Novel tridurylboranes based molecules with oligofluorene endcaps, namely tris[(9,9-dioctylfluoren-2-yl)duryl]borane (DBF1) and Tris[(9,9,9′,9′-tetraoctyl-2,2′-bifluoren-7-yl)duryl]borane (DBF2), were designed and synthesized for use in solution-processed phosphorescent organic light-emitting diodes (OLEDs). These materials show good solubility and excellent thermal stability. The photophysical study revealed that there is no significant π-conjugation between the tridurylborane core and the oligoflourene endcaps due to the strong steric hindrance of bulky duryl groups. DBF1 has sufficiently high triplet energy so as to act as host material for green phosphors. Green phosphorescent OLEDs were fabricated by partially solution-processing technique with DBF1 as host and traditional green iridium phosphor as doped emitter. An optimized device exhibited high efficiencies of 36.77 cd A−1, 23.09 lm W−1 and 10.81%, which are close to the best data for partially solution-processed green phosphorescent OLEDs containing small molecular hosts reported so far.

Small molecular tridurylborane/oligofluorene hybrids are developed for use as solution-processible host materials in green phosphorescent organic light-emitting diodes, which exhibit high electrophosphorecence efficiencies of 36.77 cd A−1 and 10.81%.Figure optionsDownload as PowerPoint slideHighlights
► Novel small molecules (DBF1 and DBF2) with tridurylboranes core and oligo-fluorene endcaps were synthesized.
► DBF1 has sufficiently high triplet energy so as to act as host material for green phosphors.
► Green phosphorescent OLEDs were fabricated by spin-coating method with DBF1 as host for iridium phosphor.
► The 36.77 cd A−1 is close to the best efficiency for solution-processed green phosphorescent OLEDs with small molecular host.