Hybrid metal sulfide/polymer solar cell active layers are fabricated employing an approach based upon the in-situ thermal decomposition of a single source metal xanthate precursor in a semiconducting polymer film. The nanomorphology of the film, the charge photogeneration yield at the donor-acceptor heterojunction and device performance are shown to be dependent upon the annealing tern perature. Photovoltaic devices based upon such layers are shown to exhibit power conversion efficiencies of similar to 2.2% under AM1.5 solar illumination thus demonstrating the potential of such nanocomposite films for photovoltaic device applications.