High-efficiency blue-green electrophosphorescent light-emitting devices using a bis-sulfone as host in the emitting layer

A bis-sulfone small molecule, 4,4′-bis(phenylsulfonyl)biphenyl has been evaluated as a host for the phosphor iridium(III) bis(2-(4,6-difluorophenyl)pyridinato-N,C2′)picolinate in blue-green organic light-emitting devices. In addition, a poly(norbornene)-based polymer functionalized with a 3,6-bis(carbazol-9-yl)carbazole moiety as a side group is utilized as a solution-processible hole-transport layer; comparison is made to the widely-used hole-transport polymer poly(N-vinylcarbazole) (PVK). At 100 cd/m2, the highest efficiency device incorporating the new polymer achieved an external quantum efficiency (EQE) of 6.9% (12.9 cd/A) with a turn-on voltage of 4.3 V. In comparison, the highest efficiency device using PVK achieved an EQE of 6.4% (11.3 cd/A) with a turn-on voltage of 6.0 V.

A bis-sulfone compound is shown to perform as a host for high-triplet-energy emitters in highly efficient blue-green phosphorescent OLEDs.Figure optionsDownload as PowerPoint slideHighlights
► Bis-sulfone small molecule as host for blue-green emitting phosphors in electrophosphorescent devices.
► New solution-processed hole-transport material based on a poly(norbornene) polymer functionalized with carbazole-based moieties.
► Bis-sulfone small molecule with large triplet energy and high synthetic flexibility for organic-light-emitting diodes.