Embodiments of photoanodes and quantum dot-sensitized solar cells (QDSSCs) comprising colloidal, cation-exchanged quantum dots are disclosed. The quantum dots include a core and an outer cation-exchanged layer having a cation composition that differs from a cation composition of the core. Methods of making the quantum dots, photoanodes, and QDSSCs also are disclosed.
ACKNOWLEDGMENT OF GOVERNMENT SUPPORT
 This invention was made with government support under Contract No. DE-AC52-06NA25396 awarded by the U.S. Department of Energy. The government has certain rights in the invention.