To rationalize the hypsochromic shift of the NCs (both CsPbBr2Cl and CsPbBr3) upon exchange with DCzGPC, we note that different capping ligands for NCs have been shown to not only affect the absolute energies of the band edges , but also the excitonic transition energy itself as described by the Brus equation. Since the size of the NCs does not decrease during ligand exchange in our work, the only free parameters in the Brus equation for describing the excitonic transition energy are the relative dielectric constant and the carrier effective masses. Evidence for an increased dielectric constant due to DCzGPC is provided by the long-term colloidal stability in polar solvents. However, a simple estimate of the total exciton binding energy shows that a change in the dielectric environment alone cannot account for the full hypsochromic shift of 120 meV observed by us (see SI for details). Therefore, we propose that an additional reduction of the effective mass of the charge carriers is responsible for the increased excitonic transition energy.