Effect of Side Chain Length Variation on the Optical Properties of PPE-PPV Hybrid Polymers

Tekin, Emine; Egbe, Daniel A. M.; Kranenburg, Johannes M.; Ulbricht, Christoph; Rathgeber, Silke; Birckner, Eckhard; Rehmann, Nina; Meerholz, Klaus; Schubert, Ulrich S.

Abstract:

New 4-fold alkoxy-substituted poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene) polymers (PPE-PPV) have been synthesized in order to elucidate the previously observed effect of side chains on the thin film properties (i.e., color variation) of PPE-PPVs. The length of the side chains attached to the PPE segments, CnH2n+1, has been varied from n ) 12 to 19. The side chains attached to the PPV segments have been kept fixed to C8H17. Polymers with n ectra obtained for inkjet printed and spin-coated thin films. However, the obtained orange-red EL emission colors are unstable upon increase of the applied voltage. A blue shift of up to 100 nm was observed. All the polymers exhibited very high relative and absolute PL quantum yields in solution (∼70%). Their solid-state absolute PL quantum yield was found to be between 10 and 20%. Polymeric light emitting diodes (PLED) with the following structure ITO//PEDOT:PSS//Pn/8//Ca//Ag were fabricated. The devices were fully characterized and showed low turn-on voltages.

Year:

2008

Type of Publication:

Article

Journal:

Chemistry of Materials

Volume:

20

Pages:

2727 - 2735