A blue-light-emissive fluorene-based polyoxadiazole, an n-type polyfluorene derivative, was synthesized by both one-step and two-step methods. Directly polymerized poly[(9,9'-didodecylfluorene-2,7-diyl)-alt-(1,3,4-oxadiazole-2,5-diyl)] (PFOx-DP) exhibited a higher molecular weight and a more efficient photoluminescence quantum yield than kpoly[(9,9'-didodecylfluorene-2,7-diyl)-alt-(1,3,4oxadiazole-2,5-diyl)] (PFOx) prepared via a polyhydrazide precursor, poly[9,9'-didodecylfluorene-2,7-(2,5-dihydrazide-1,3,4-oxadiazole). Both polymers, differently prepared, showed similar photoluminescent properties in 1,2-dichloroethane. However, in a film state, the influence of the interchain interactions on the photoluminescence of PFOx with the lower molecular weight was larger than on the photoluminescence of PFOx-DP. The electron-deficient property of an oxadiazole group in the polymer backbone resulted in low-lying highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of -6.29 and -3.26eV, respectively, of the polymer suitable for electron-transport/hole-blocking layers and emissive layers in multilayer electroluminescence devices. (C) 2004 Wiley Periodicals, Inc.