Raman Microprobe Analysis of Elastic Strain and Fracture in Electrophoretically Deposited CdSe Nanocrystal Films

Abstract

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.

Viscoplastic and Granular Behavior in Films of Colloidal Nanocrystals

“…The value of the elastic modulus previously deduced indirectly via Raman spectroscopy of the CdSe cores under tension for the 3200 nm EPD film described in Table I (9.7 GPa, assuming 0:3) [13] is very similar to that measured here via nanoindentation ( 8 GPa) in which the deformation is largely compressive.…”

Study on the interaction between 2‐mercaptoethanol, dimercaprol and CdSe quantum dots

“…As shown in Fig. 7, the peak at 460 cm -1 is the characteristic band for CdSe QDs (25). Comparing with the previous reported results, the shift of the Raman peaks may be due to the changes of the QDs sizes.…”

A mirage study of CdSe colloidal quantum dot films, Urbach tail, and surface states

“…In dried films of quantum dots, Raman spectroscopy has shown that the dots may be strained. 24 However, if strain 12 or electric field 11 were the source of the large shifts or long tail, all three systems should behave similarly, therefore the absence of such effects for CdSe/ZnS suggests that these effects are weak.…”