Collective optical behavior from coupled quantum dots visualized by wavelength-resolved and polarization-resolved super-resolution microscopy

Abstract Applications of colloidal semiconductor quantum dots (QDs) that place particles into close proximity with other QDs must contend with the effects of interactions between the particles. Electronic coupling facilitates energy transfer, but these environments can also alter the native properties of the individual QDs. How QDs behave collectively due to coupling is a largely unexplored topic. We developed a super-resolution wavelength-resolving and polarization-resolving microscope to capture correlations among the signatures QD coupling. Nanoassemblies containing 2—10 QDs exhibited features of energy transfer: regions of high fluorescence activity from exciton funneling to acceptor particles, and spectral-intensity distributions consistent with donor/acceptor relationships. Spatial distributions of these features were localized with ~10 nm precision, on the order of the size of individual particles. Unexpectedly, polarization signatures from nanoassemblies were uniform, indicating a single emission polarization state for a group of QDs. This demonstrates a strong electronic coupling that alters the native behavior of the individual particles.