Influence of solvent on aqueous CdTe nanocrystals: Theoretical and experimental investigation

We investigated the influence of solvent on the optical properties of CdTe nanocrystals from the viewpoints of both experiments and theoretical calculation. Experimentally, the influence of water, methanol, ethanol and acetone on the optical properties of CdTe nanocrystals was investigated. The results indicate that the relative dielectric constant of solution is the main factor affecting the optical properties of CdTe nanocrystals. The larger relative dielectric constant of the solution, the smaller emission red shift or the smaller Stokes shift is observed. Moreover, the solvent-induced Stokes shift of CdTe nanocrystals is also showed a size-dependent trend. Theoretically, we have found that the calculated emission wavelengths, have the same rule with experiment. Different conformations have different Dipole Moment, resulting in different modifying constant in formula of influence of solvent on molecule. The main differences between small molecular and nanocrystals is that nanocrystals shows a size-dependent Stokes shift in solution.

► Nanocrystals shows a solvent-dependent Stokes shift.
► Solvent dielectric constant is the main factor for the Stokes shift of nanocrystals.
► The size of nanocrystals affect the amount of Stokes shift.