Synthesis and characterization of a novel symmetrical sulfone-substituted polyphenylene vinylene (SO2EH-PPV) for applications in light emitting devices.

A novel symmetrical alkylsulfonyl-substituted poly(phenylenevinylene) derivative, poly [2,5-bis-(2'-ethylhexylsulfonyl)-1,4-phenylene)vinylene] (SO2EH-PPV), was synthesized via palladium-catalyzed Stille coupling, and its electronic and optical properties were investigated. The novel PPV derivative was characterized by NMR, UV-visible absorption, photoluminescence, gel permeation chromatography, infrared spectroscopy, and cyclic voltammetry (CV). The polymer with Mw of 27,800 and a polydispersity index of 2.6 is readily soluble in common organic solvents, such as THF, chloroform, and toluene. The fluorescence quantum yield of the polymer, determined against rhodamine 6G in dilute aqueous solutions, was 0.95. The HOMO and LUMO levels of SO2EH-PPV were calculated to be -6.0 and -3.61 eV, respectively. The results obtained by CV suggest that SO2EH-PPV is a strong electron acceptor polymer. Single layer stable polymer light-emitting diode devices with the configuration of (ITO/PEDOT:PSS/SO2EH-PPV polymer/Al) were fabricated exhibiting a green light emission.