Cadmium-based nanocrystals and nanocomposites at the air-water interface

Two cadmium-based nanocrystals were studied, cadmium selenide and cadmium telluride, which have potential applications in optoelectronic devices. CdSe quantum dots and nanorods were synthesized with a functional ligand, allowing for the formation of nanocomposites where a vinyl terminated conjugated polymer is attached through a mild Heck coupling. This provided a direct connection between the polymer and quantum, yielding improved charge transport from the polymer to the quantum dot. The QD-CP nanocomposite was placed on the air-water interface and studied for the first time. The Langmuir isotherm was obtained and showed intriguing packing behavior, which a model system was proposed where the conjugated polymer bends and folds only at the conjugation length. A photovoltaic device was fabricated and showed poor performance, yet high short circuit current. Cadmium telluride tetrapods were synthesized in a manner that easily controlled the arm width and therefore absorption peak and onset. The tetrapods were placed on the airwater interface and showed unique dewetting behavior, forming ribbon like structures at the onset of pressure. At higher pressures, flower aggregated formed along the ribbon structure and eventual network structure formed. CdSe nanorods were synthesized in the presence of a functional ligand. Initial NMR results show promise in this one batch synthesis, compared to the previous work done through ligand exchange. This shows promise and future work is continuing through colleagues in the Lin Research Group.