Vamvounis, George, Schulz, Gisela L., and Holdcroft, Steven (2005) Enhanced blue-violet emission from poly(fluorene-co-thiophene) host-guest systems. Macromolecules, 37 (24). pp. 8897-8902.

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Abstract

Host-guest systems based on novel poly(fluorene-alt-thiophene) (PFT) polymers exhibiting enhanced solid-state blue-violet emission are presented. These polymers were synthesized via Suzuki polycondensation of 9,9-dihexylfluorene-2,7-bis(trimethyleneborate) with 3,4-dibromothiophene and/or 2,7-dibromo-9,9-dihexylfluorene. The host is a UV-violet-emitting, alternating 3,4-linked poly(fluorene-cothiophene), and the guests are poly(9,9-dihexylfluorene) (PDHF) segments, which are prepared by either blending or copolymerization. In both cases, blue-violet emission is observed in the solid state. The solid-state quantum yields of luminescence (Phi(pl)) are determined. Blended and copolymer systems showed a pronounced difference: Phi(pl) of blends were independent of polymer composition while copolymers were strongly composition-dependent. These differences are attributed to morphological differences, wherein blends are phase-segregated while the copolymer system are best described as solid solutions of the guest in the host. Copolymers gave up to 10-fold enhancement in the external quantum efficiency of electroluminescence compared to the case of PDHF.

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