The mechanical stability of nanocrystal films is critical for applications, yet largely unexplored. Raman microprobe analysis used here to probe the nanocrystal cores of thick, fractured electrophoretically deposited films of 3.2 nm diameter CdSe nanocrystals measures approximately 2.5% in-plane tensile strain in cores of unfractured films. The crack dimensions determine the overall in-plane film strain, approximately 11.7%, and the film biaxial modulus, approximately 13.8 GPa, from which the biaxial modulus of the trioctylphosphine oxide ligand matrix is inferred, approximately 5.1 GPa.

The broadening of the exciton absorption peak in films composed of small, ∼2 nm diameter CdSe nanocrystals capped by 1-thioglycerol has been interpreted as evidence of interdot carrier coupling. This exciton broadening is seen here for 2.1 nm diameter CdSe nanocrystal arrays, and part of it is correlated with the loss of over half of the 1-thioglycerol molecules from the nanocrystal surfaces. These ligands are even more weakly bound in films of 4.1 nm diameter particles, as evidenced by the smaller shift in their ∼2560 cm -1 S-H stretching peak and the faster decay of this peak vis-a `-vis that of the smaller particles, but no exciton broadening is observed for these films.