A photovoltaic cell can include a dopant in contact with a semiconductor layer. The photovoltaic cell can include a transparent conductive layer and a first semiconductor layer in contact with the transparent conductive layer, the first semiconductor layer including magnesium. In certain circumstances, a substrate can be a glass substrate. In other circumstances, a substrate can be a metal layer. The first semiconductor layer can include CdS. The first semiconductor layer can have a thickness of between about 200 or 3000 Angstroms. The first semiconductor layer can include 1-20% magnesium. A method of manufacturing a photovoltaic cell can include providing a transparent conductive layer and depositing a first semiconductor layer in contact with the transparent conductive layer, the first semiconductor layer treated with magnesium.