Solar cells and methods for use and making these solar cells are disclosed. An exemplary solar cell includes a first electrode. The solar cell also includes a nanocrystal film of a single material disposed in contact with the first electrode. The solar cell also includes a second electrode disposed in contact with the nanocrystal film, not in contact with the first electrode.
 The United States Government has rights in this invention under Contract No. DE-AC36-08GO28308 between the United States Department of Energy and the Alliance for Sustainable Energy, LLC, the Manager and Operator of the National Renewable Energy Laboratory.