(N-2-ethylthexyl)-3(6)-phenothiazinylene vinylene-co-9,10-anthrylene vinylene), KPD-1, as a new low molecular weight dopant was synthesized. Poly(1,12-dodecanedioxy-2-methoxy-1,4-phenylene-1,2-ethenylene-1,1'-biphenyl-4,4'-ylene-1,2-ethenylene-3-methoxy-1,4-phenylene), [Poly(BFMP (12)-AV)] as a matrix polymer was also prepared by Honer-Emmons condensation. Single- and multi-layered PLEDs were fabricated with a mixture of dopant/matrix polymer as an emissive layer The effect of dopant/matrix polymer and device structures on the energy transfer and electro-optical properties of doped PLEDs was discussed in terms of emission color changes and luminescence efficiency of doped PLEDs.