Semiconductor Nanocrystal Assemblies:  Experimental Pitfalls and a Simple Model of Particle−Particle Interaction

Interactions in semiconductor nanocrystal assemblies have been studied on films of the cluster crystal compounds Cd 17 S 4 (SCH 2 CH 2 OH) 26 and Cd 32 S 14 (SCH 2 CH(CH 3 )OH) 36 prepared by spin coating. Misinterpretations of observed alterations of transition energies in theses structures are avoided by the choice of an integrating sphere as the experimental setup. The resulting “real” redshift of the transition energy is explained by dipole−dipole interactions of the semiconductor nanocrystals in the films. When covalently linked, the clusters may also interact electronically.