Doped Semiconductor Nanocrystals: Synthesis, Characterization, Physical Properties, and Applications

This review focuses on recent progress in the study of doped semiconductor nanocrystals prepared by direct solution chemical routes. The emphasis is on materials that can be prepared and handled as high-quality colloidal nanocrystalline suspensions, allowing them to be easily processed by a variety of conventional methods and incorporated into glasses, polymers, or hetero-architectures, appended to biomolecules, or assembled into close-packed ordered arrays, and providing many opportunities related to materials processing and nanoscale engineering. In contrast with the tremendous successes achieved with the preparation of pure (and core/shell or related heteroepitaxial) semiconductor nanostructures, solution methods have not yet excelled at preparing doped nanocrystals, but recent advances portend an exciting future for this area. The review is divided into three themes: synthesis of colloidal doped inorganic nanocrystals (Section II), analytical techniques for probing synthesis (Section III), and physical properties of the resulting materials (Section IV). In Section V, examples are presented involving the use of colloidal doped semiconductors as building blocks in higher dimensionality structures. The review focuses largely on 3d transition metal ions as dopants, since those with open d-shell electronic configurations have various unique physical properties including magnetic ground states and low-energy excited states that make them attractive for altering the magnetic, absorptive, photoluminescent, or other physical properties of their host semiconductors.