Electruluminescence (EL) in conjugated polymers based on phenyleneethynylene and thiophene (PPE) with C—C triple bonds in their main chains were studied．It was found that the emitting wavelength will red-shift by introduction of thiophene which is an electron-rich moiety

the results suggest that electron-rich moieties should increase effective conjugation length．Our results also show that the incorporation of thiophene units into PPE may significantly reduce the rigid-rod conformation and improve the processibility．