title: Incorporation of spiroxanthene units in blue-emitting oligophenylene frameworks: a new molecular design for OLED applications.
abstract: We report herein the incorporation of xanthenyl units into two extended π-conjugated phenylene systems, namely indenofluorene and pentaphenylene. Thus, dispiroxanthene-indenofluorene (DSX-IF) and dispiroxanthene-ladderpentaphenylene (DSX-LPP) have been designed and synthesized through short and efficient synthetic approaches. These two molecules possess a 3π-2-spiro architecture (3π-systems/2-spiro bridges), in which two xanthenyl cores are spirolinked to a π-conjugated backbone either indenofluorene for DSX-IF or pentaphenylene for DSX-LPP. The structural, electrochemical, and photophysical properties of these blue/violet emitters have been studied in detail and compared to those of their 'all carbon' analogues with spirofluorenyl cores instead of spiroxanthenyl cores, namely dispirofluorene-indenofluorene (DSF-IF) and dispirofluorene-ladderpentaphenylene (DSF-LPP), previously reported in the literature. Finally, the application of DSX-IF and DSX-LPP as new light-emitting materials in nondoped organic light emitting diodes is reported. A detailed optical study of the different electroluminescence spectra is notably presented, with an emphasis 1) on the origin of the low-energy emission band observed in the case of DSX-LPP and 2) on the unexpected optical contribution of the well-known hole-transporting-layer NPB (N,N'-di(naphtyl)-N,N'-diphenyl(1,1'-biphenyl)-4,4'-diamine).
authors.affiliation: Université de Rennes 1-UMR CNRS 6226, Sciences Chimiques de Rennes-MaCSE group, Campus de Beaulieu, Rennes, France. cyril.poriel@univ-rennes1.fr
authors.forename: Cyril
authors.initials: C
authors.lastname: Poriel
authors.forename: Nicolas
authors.initials: N
authors.lastname: Cocherel
authors.forename: Joëlle
authors.initials: J
authors.lastname: Rault-Berthelot
authors.forename: Laurence
authors.initials: L
authors.lastname: Vignau
authors.forename: Olivier
authors.initials: O
authors.lastname: Jeannin