Synthesis and characterization of new orange-red light-emitting PPV derivatives with bulky cyclohexyl groups

A series of 2,5-dialkoxy substituted poly (1,4-phenylenevinylene) derivatives containing a rigid and bulky cyclohexyl group in the side chain, poly [2-(7-cyclohexylheptyloxy)-5-butoxy-1,4-phenylenevinylenel (PBCyHpPV), Poly [2-(6-cyclohexylmethoxyhexyloxy)-5-butoxy-1,4-phenylenevinylene] (PBCyHxPV), Poly[2,5-di-(6-cyclohexylmethoxy-hexyloxy)-1,4-phenylenevinylene] (PDCyHxPV) were synthesized via the Gilch polymerization. The synthesized polymers were soluble in common organic solvents and showed good thermal stability up to 370°C. The maximum absorption of PBCyHpPV, PBCyHxPV and PDCyHxPV as thin films was at 513 nm, 515 nm, 511 nm, respectively. Photoluminescence maximum emission of above polymers appeared at 590 nm, 597 nm, 590 nm, respectively. The electroluminescence (EL) maxima of the polymers appeared around 585-590 nm, and also showed another shoulder around 630 nm strongly. PDCyHxPV showed the highest EL efficiency and EL power than those of other polymers due to the dilution effect of the two rigid and bulky cyclohexyl groups.