| The major part of this thesis is devoted to interdot interactions in CdSe nanocrystal arrays at elevated pressure. Three-dimensional arrays of organically passivated CdSe nanocrystals were investigated under hydrostatic pressure using photoluminescence (PL) and absorption spectroscopies. Interdot separations were varied coarsely by varying the organic ligand on the nanocrystal and finely by applying hydrostatic pressure. The PL and absorption spectra of solutions and arrays of CdSe nanocrystals capped by tri-n-octylphosphine oxide (TOPO) or tri-n-butylphosphine oxide (TBPO) are the same up to 60 kbar. In contrast, there is a distinct difference between the pressure dependence of CdSe/pyridine dots in solution and arrays. This different dependence can be attributed to several factors, including possible carrier coupling between neighboring nanoparticles through the organic ligands capping the respective particles that would lead to a decrease in carrier confinement energy.; The kinetics of solvent and organic ligand of CdSe nanocrystal arrays during the assembly were quantitatively investigated. Attenuated total reflection is shown to be a quantitative real-time probe of several important features of nanocrystal self-assembly by following the infrared absorption of the solvent and the organic ligands that passivate the nanocrystal surface. During the self-assembly of a 250 monolayer array of CdSe nanocrystals capped by pyridine, the pyridine solvent molecules evaporate in ∼30–40 min and the pyridine-capping molecules leave the array very slowly, apparently limited by diffusion, with ∼30 ± 8% remaining after three days.; The method of spin-assisted self-assembly was used to produce sub-micron thick films of CdSe nanocrystals. The uniformity was investigated with various spin rate and solvents; the films made from a hexane/octane mixture at a spin rate of 100 RPM with intermittent pauses resulted in the least fluctuations in film thickness. Using optical microscopy, profilometry, and ellipsometry, the surface morphology was studied and aligned-holes, rod-, V-, Y-, and brick-like surface features were observed. |
