Effects of alkylamine chain length on the thermal behavior of CdSe quantum dot glassy films

The competition between dimensional and domain effects for the packing of amphiphilic passivants on CdSe quantum dot (QD) surfaces is examined using temperature-dependent attenuated total reflection infrared spectroscopy. The results indicate that at very small particle sizes (r < 22 Angstrom) disordered packing of the organic passivant arises due to the lack of an available thermodynamically stable packing domain for the passivant on the QD facets. At particle sizes r > 22 Angstrom, a stable chain domain can be established where the chain packing thermodynamics is governed by purely dimensional effects related to the ratio of the chain length (<L>) to the particle radius (r). Using a mean field statistical mechanical calculation, we find the theoretical calculations predict the observed <L>/r passivant layer stabilization for QD systems.