By doping poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) with poly(2-methoxy-5-(3'-7'-dimethyloctyloxy)-1,4-phenylenevinylene) (MDMO-PPV), improved photoconductive characteristics were obtained for an organic photoconductive device fabricated by a conventional spin-coating process. This device had a maximum external quantum efficiency (EQE) of 2.4% at 15MV/m when the doping ratio of MDMO-PPV-doped F8BT was 50wt%. This EQE is approximately 5.1 times higher than that (0.47%) of a reference device with undoped F8BT. In addition, the signal-to-noise ratio (i.e., photocurrent/dark current) was improved by doping MDMO-PPV because of the reduced dark current density. The highest signal-to-noise ratio obtained was 447.