A method for forming a thin film photovoltaic device is provided. The method includes providing a transparent substrate comprising a surface region. A first electrode layer is formed overlying the surface region. A chalcopyrite material is formed overlying the first electrode layer. In a specific embodiment, the chalcopyrite material comprises a copper poor copper indium disulfide region. The copper poor copper indium disulfide region having an atomic ratio of Cu:In of about 0.95 and less. The method includes compensating the copper poor copper indium disulfide region using a sodium species to cause the chalcopyrite material to change from an n-type characteristic to a p-type characteristic. The method includes forming a window layer overlying the chalcopyrite material and forming a second electrode layer overlying the window layer.