NOVELTY - An organic silicon polymer single wall carbon nanotube composite is formed by modifying the surface of single wall carbon nanotube by organic silicon polymer (I).    USE - Organic silicon polymer single wall carbon nanotube composite is used for oxide semiconductor for manufacture of photoelectrode (both claimed) used for photoelectric conversion devices e.g. solar cell and organic electroluminescent element.    ADVANTAGE - The organic silicon polymer single wall carbon nanotube composite has favorable workability, excellent photoelectric conversion efficiency and electroluminescent efficiency. The semiconductor property of single wall carbon nanotube is not impaired by modification with organic silicon polymer.    DETAILED DESCRIPTION - An organic silicon polymer single wall carbon nanotube composite is formed by modifying the surface of single wall carbon nanotube by organic silicon polymer of formula: -(Ar-CC-(Si(R)2)m-CC)n- (I).    m=1-3;    R=1-20C alkyl or optionally substituted phenyl;    Ar=bivalent condensed-ring aromatic group which consists of 2-8 benzene rings;and    n=5-2000.    INDEPENDENT CLAIMS are included for the following:    (1) manufacture of organic silicon polymer single wall carbon nanotube composite solution, which involves mixing organic silicon polymer and single wall carbon nanotube in an organic solvent;    (2) oxide semiconductor formed by supporting porous titanium dioxide on organic silicon polymer single wall carbon nanotube composite;    (3) photoelectrode (6) which consists of transparent conductive film and porous semiconductor layer (3) containing oxide semiconductor sequentially provided on a transparent substrate (1); and    (4) manufacture of photoelectrode, which involves applying porous titanium dioxide microparticles on transparent conductive film, sintering to form porous titanium dioxide layer, contacting organic silicon polymer single wall carbon nanotube composite solution with titanium dioxide layer, heating and irradiating light.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic cross-sectional view of structure of solar cell.    Glass substrate (1)    Fluorine-doped tin oxide layer (2)    Porous semiconductor layer (3)    Counter electrode (4)    Photoelectrode (6)