A novel soluble conjugated polymer, poly [(2,5-diphenylene-1,3,4-oxadiazole)-4,4＇-vinylene] (O-PPV), containing an electron-transporting group on the main chain of PPV, was synthesized according to HORNER mechanism. The oligo-polymer with M-w = 1000 and T-d = 270 degrees C is soluble in chloroform and tetrahydrofuran. The photoluminescent (PL) properties were investigated using different concentrations of solid-state O-PPV/PEO blends absorption and selective excitation measurements. The results show that PL arises from interchain charge-transfer states in solid-state O-PPV. Compared with the analogous single-layer device constructed with PPV (ITO/PPV/Al), which emits two peaks at lambda = 520 nm and 550 nm (shoulder), the electroluminescence (EL) spectrum of the device [ITO/O-PPV(80 nm)/Al] is a broad peak at lambda(max) = 509 nm. The quantum efficiency (0.13%) of the device ITO/O-PPV/Al is much higher than that of the device ITO/PPV/Al, due to the introduction of the electron-transporting group-oxadiazole units in the main chain of PPV.