NOVELTY - A nanowire, comprises a poly(3-pentylthiophene).    USE - As a nanowire in composites and photovoltaic device (claimed) i.e. solar cells.    ADVANTAGE - The nanowire provides highly efficient polymer/fullerene solar cells in which a 3-D network of pre-assembled polymer semiconductor nanowires serves as the donor component in a sea of fullerene acceptor. In this approach, an electrically bicontinuous nanoscale morphology is realized without going through the difficult path of blend phase-separation phenomena. Photovoltaic cells with 3% power conversion efficiency are achieved by using poly(3-butylthiophene) nanowires. Thus, poly(3-butylthiophene) exhibits photovoltaic properties that are comparable to the much studied poly(3-hexylthiophene). The poly(3-butylthiophene)-nanowire suspension is quite stable; the nanowires do not dissolve in the solvent by dilution and they do not settle or precipitate in over one month.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a composite, comprising: (a) at least one poly(3-alkylthiophene) nanowire; and (b) at least one bulk heterojunction solar cell acceptor compound;    (2) method (m1) for making a composite, involving depositing a mixture of at least one poly(3-alkylthiophene) nanowire and at least one bulk heterojunction solar cell acceptor compound onto a substrate to provide a composite;    (3) depositing (m2) the mixture of at least one poly(3-alkylthiophene) nanowires and at least one bulk heterojunction solar cell acceptor compounds onto a substrate involving spin coating, drop coating, blade coating, spray coating, or screen printing the mixture;    (4) a photovoltaic device, comprising:(a) a hole-collecting electrode;(b) a photovoltaic layer comprising at least one poly(3-alkylthiophene) nanowires, and at least one bulk heterojunction solar cell acceptor compounds; and (c) an electron-collecting electrode;    (5) method (m3) for making a photovoltaic device, either involving: (a) forming a photovoltaic layer on a hole-collecting electrode, where the photovoltaic layer comprises at least one poly(3-alkylthiophene) nanowires, and at least one bulk heterojunction solar cell acceptor compounds; and (b) forming an electron-collecting electrode on the photovoltaic layer or (a1) forming a photovoltaic layer on an electron-collecting electrode, where the photovoltaic layer comprises at least one poly(3-alkylthiophene) nanowires, and at least one bulk heterojunction solar cell acceptor compounds; and (b1) forming a hole-collecting electrode on the photovoltaic layer;    (6) forming (m4) the photovoltaic layer involving spin coating, drop coating, blade coating, spray coating, or screen printing a composition comprising at least one poly(3-alkylthiophene nanowires, and at least one bulk heterojunction solar cell acceptor compounds;    (7) generating (m5) an electrical current, involving exposing the photovoltaic layer of the photovoltaic device to electromagnetic radiation of a wavelength sufficient to generate electrons and holes in the photovoltaic layer.