Spirobenzofluorene linked anthracene derivatives: Synthesis and application in blue fluorescent host materials

Blue light-emitting anthracene-based host materials with a spiro[benzo[c]fluorene-7,9′-fluorene] core, 5-(10-(naphthalen-2-yl)anthracen-9-yl)spiro[benzo[c]fluorene-7,9′-fluorene] (NA-SBFF) and 5-(10-(4-(naphthalen-1-yl)phenyl)anthracen-9-yl)spiro[benzo[c]fluorene-7,9′-fluorene] (NPA-SBFF), were designed and synthesized via two-step Suzuki coupling reactions. Introduction of a spiro group into the structure of the anthracene moieties lead to a reduction in crystallization tendency, and a high glass transition temperature was observed. Typical blue fluorescent organic light emitting diodes with the configuration of ITO/N,N′-diphenyl-N,N′-bis[4-(phenyl-m-tolyl-amino)phenyl]biphenyl-4,4′-diamine (DNTPD)/N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (NPB)/HOST: Dopant/tris(8-hydroxyquinoline)aluminum (Alq3)/LiF were developed using SBFF-type anthracene derivatives as a host material and N,N,N′,N′-tetraphenylspiro[benzo[c]fluorene-7,9′-fluorene]-5,9-diamine (TPA-SBFF) as a dopant material. A device obtained from NA-SBFF doped with TPA-SBFF showed blue color purity of 0.146 and 0.167, a luminance efficiency of 8.65 cd/A, and an external quantum efficiency >6.01% at 8.0 V.

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► New anthracene host materials with spiro[benzo[c]fluorene-7,9′-fluorene] were prepared.
► Thermally stable and high glass transition temperature up to 263 °C.
► Deep blue fluorescence OLEDs with a color purity of (0.146, 0.167) were developed.
► An efficiency (8.65 cd/A at 8.0 V) and an external quantum efficiency >6.01%.