Substituent-induced electroluminescence polymers-poly[2-(2-dimethyldo-decylsilylphenyl)-1,4-phenylenevinylene] [(o-R3Si)PhPPV], poly [2-(3-dimethyldodecyl-silylphenyl)-1,4-phenylenevinylene] [(m-R3Si)]PhPPV], and poly [2-(4-dimethyldodecyl-silylphenyl)-1,4-phenylenevinylene] [(p -R3Si)PhPPV] -were synthesized according to the Gilch polymerization method. The band gap and spectroscopic data were tuned by the dimethyldodecylsilyl substituent being changed from the ortho position to the para position in the phenyl side group along the polymer backbone. The weight-average molecular weights and polydispersities were 8.0-96 X 10(4) and 3.0-3.4, respectively. The maximum photoluminescence wavelengths for (o-R3Si)PhPPV, (m-R3Si)PhPPV, and (p-R3Si)PhPPV appeared around 500-530 nm in the green emission region. Double-layer light-emitting diodes with an indium,tin oxide/poly(3,4-ethylenedioxythiophene)/polymer/Al configuration were fabricated with these polymers. The turn-on voltages and the maximum brightness of (o-R3Si)PhPPV, (m-R3Si)]PhPPV, and (p-R3Si)PhPPV were 6.5-8.7 V and 1986-5895 cd/m(2), respectively. (C) 2004 Wiley Periodicals, Inc.