One-dimensional conjugated polymers can be used to build unperturbed percolation pathways that transport electric charges in the active layer of an organic photovoltaic (OPV) cell. Electrospinning is known to be a facile method for the preparation of 1-D nanofibers, but the diameters of electrospun conjugated polymers have previously been too large for OPV cells. In particular, it has not been possible to electrospin poly(3-hexylthiophene) (P3HT) to produce homogeneous nanofibers. We report a new method for the preparation of homogeneous P3HT nanofibers with diameters less than 100 nm and examine the photoluminescence (PL) properties of these nanofibers as a preliminary test of their use in an OPV cell. Nanofibers of P3HT with diameters less than 100 nm can be successfully and simply electrospun by using the proposed method, in particular without adopting a dual nozzle system, with the aid of an auxiliary polymer, polyethylene oxide (PEO), and a polar solvent mixture consisting of chloroform, dimethylformamide (DMF), and acetic acid. After removal of the auxiliary polymer, a composite film composed of virgin P3HT nanofibers and PCBM was found to exhibit almost 100% PL quenching. These results suggest that the proposed method can be used to produce P3HT nanofibers with an efficient photo-energy conversion structure that is useful in OPV cells.