Hyper-branched CdTe nanostructures based on the self-assembling of quantum dots and their optical properties.

As the priority of interconnects and active components in nanoscale optical and electronic devices, three-dimensional hyper-branched nanostructures came into focus of research. Recently, a novel crystallization route, named as "nonclassical crystallization," has been reported for three-dimensional nanostructuring. In this process, Quantum dots are used as building blocks for the construction of the whole hyper-branched structures instead of ions or single-molecules in conventional crystallization. The specialty of these nanostructures is the inheritability of pristine quantum dots' physical integrity because of their polycrystalline structures, such as quantum confinement effect and thus the luminescence. Moreover, since a longer diffusion length could exist in polycrystalline nanostructures due to the dramatically decreased distance between pristine quantum dots, the exciton-exciton interaction would be different with well dispersed quantum dots and single crystal nanostructures. This may be a benefit for electron transport in solar cell application. Therefore, it is very necessary to investigate the exciton-exciton interaction in such kind of polycrystalline nanostructures and their optical properites for solar cell application. In this research, we report a novel CdTe hyper-branched nanostructures based on self-assembly of CdTe quantum dots. Each branch shows polycrystalline with pristine quantum dots as the building units. Both steady state and time-resolved spectroscopy were performed to investigate the properties of carrier transport. Steady state optical properties of pristine quantum dots are well inherited by formed structures. While a suppressed multi-exciton recombination rate was observed. This result supports the percolation of carriers through the branches' network.

Hyperbranched CdTe nanostructures via a self-assembly route: optical properties.

In this work, we report a luminescent nanobundle structure formed by a hierarchical self-assembly process of thioglycolic acid (TGA)-capped CdTe quantum dots (QDs). The luminescence intensity of CdTe nanostructures is high enough to get a clear one-photon excitation confocal image. High contrast two-photon excitation confocal images suggest that the nonlinear properties of pristine QDs are well inherited by the formed CdTe nanostructures. The controllability of the structures and inheritance of the optical properties of the building units make the self-assembled nanostructures new generation materials.