A compound film may be formed by formulating a mixture of elemental nanoparticles composed of the Ib, the IIIa, and, optionally, the VIa group of elements having a controlled overall composition. The nanoparticle mixture is combined with a suspension of nanoglobules of gallium to form a dispersion. The dispersion may be deposited onto a substrate to form a layer on the substrate. The layer may then be reacted in a suitable atmosphere to form the compound film. The compound film may be used as a light-absorbing layer in a photovoltaic device.