Conjugated polymers doped with fullerenes have shown promising application in photovoltaic cells, in which photoinduced charge transfer takes place. Here, we report a novel composite that was prepared by in situ polymerization of a-conjugated hyperbranched polysilane in the presence of fullerene. Both of the hyperbranched polysilane and fullerene have 3D structures, which are propitious to preparing materials with interpenetrating structure. The resulting composite has good solubility in common organic solvents and the UV spectrum edge suggests a low bandgap. Photoluminescence quenching in the composite is shown by the PL spectra and is also observed from the fluorescence microscopy images, which may be ascribed to the PCT from the hyperbranched polysilane to the fullerene. The composite was also characterized by GPC, FTIR, NMR, XRD, and TGA. Through further discussion, there may be pi-pi stacking between hyperbranched polysilane and fullerene, which enhances the photoinduced charge transfer. (c) 2007 Wiley Periodicals, hic.