Improved electroluminescent efficiencies in polymer light-emitting diodes(LEDs) have been reported to be obtained either by constructing multi-layer devices or by using polymer blends in a light emitting layer. In this work, conjugated copolymers, poly((PZV-PV)-co-(CZV-PV)) containing (N-2-ethylhexyl)-3,6-phenothiazinylene vinylene(PZV) unit and (N-2-ethylhexyl)-3,6-carbazolylene vinylene(CZV) unit in different ratio were synthesized by Homer-Emmons reaction utilizing potassium t-butoxide. Homopolymers, poly(PZV-PV) and poly(CZV-PV) were also synthesized. Polymer LED's fabricated with poly(PZV-PV) and poly(CZV-PV) homopolymers as light emitting layers exhibited EL maximum at 570nm and 500nm, respectively. LED's made with poly((PZV-PV)-co-(CZV-PV)) copolymers, however, showed EL maxima shifted to longer wavelengths.