Measuring exciton-phonon coupling in semiconductor nanocrystals

At low excitation density, the dynamics of excitons in semiconductor nanocrystals are largely dictated by their interactions with the underlying atomic lattice. This exciton-phonon coupling (EPC) is responsible, for example, for absorption and luminescence linewidths at elevated temperatures, relaxation processes following optical excitation, and even degradation of quantum coherent applications. Characterizing and understanding EPC is therefore central to guiding rational design of colloidal nanocrystal materials and their device applications. In this review, we compare different spectroscopic methods of measuring exciton-phonon interactions and the complementary information that they provide. We emphasize the development of a new technique, termed multidimensional coherent spectroscopy, that circumvents many of the limitations of traditional methods.