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Polymers and Polymer Composites

FILM MORPHOLOGY AND ELECTROLUMINESCENCE OF POLY[9,9-DI-(2′-ETHYLHEXYL) FLUORENYL-2,7-DIYL] BLENDED WITH A HOLE TRANSPORTING POLYMER

September 1, 2010 By: Qiushu Zhang Research article

Title: FILM MORPHOLOGY AND ELECTROLUMINESCENCE OF POLY[9,9-DI-(2′-ETHYLHEXYL) FLUORENYL-2,7-DIYL] BLENDED WITH A HOLE TRANSPORTING POLYMER
Page Range: p.469-476
Author(s): Qiushu Zhang
File size: 365K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 18
Issue No: No.9

Abstract
This paper reports on the phase-separated film morphology and electroluminescence (EL) of a polyfluorene, poly[9,9-di-(2′-ethylhexyl)fluorenyl-2,7-diyl], blended with the hole transport material, poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(N,N’-bis(4-butylphenyl -1,1′-biphenylene-4,4′-diamine))]. The film morphology changes remarkably with the blend ratio. Other factors like polymer solution concentration, substrate and film thickness could also influence the film morphology. The addition of the hole-transporting polymer to the host polymer improved device properties of light-emitting diodes (LEDs). The maximum luminance achieved was 884 cd/m2. The maximum external quantum efficiency of the blended polyfluorene devices was 0.1%, which is more than three times higher than that of the pristine polyfluorene LEDs. The introduction of the hole-transporting polymer also modifies the EL spectrum. For the blend-based devices, the EL peaked at 504 nm, having a blue shift of 33 nm compared to that of the single polymer based devices. Phase-separated domains, or interactions at their interfaces, may play a role in the improved device performance. 28 Refs.

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