For a fixed NC diameter, NCs with a higher doping percentage logically contain a larger number of electrons per NC (<Nsys>) and a higher electron density (<nsys>) after the synthesis than NCs with smaller doping percentage (Figure ). Since the width of the depletion region is dependent upon the doping percentage, NCs with a higher doping percentage generally have a larger plasmonic core than NCs with a smaller doping percentage. Considering that we have employed relatively large doping percentages throughout our study (>4.5% Sn), the volume fractions of our plasmonic cores are high and do not vary drastically for different doping percentages (Figure ). Nonetheless, when electrons are supplied through chemical doping, the size of the plasmonic core increases along with a concomitant increase in the core electron density for all NCs (Figure ). Irrespective of the doping percentage, there is an almost constant addition of <ntitr> ~ 2.38 x 10 20 cm -3 to the total electron density for different doping percentages of 8 nm Sn:In2O3 NCs (Figure ). We note that this is not the maximum achievable electron density in the NCs, as the volume fraction of the plasmonic core hasn't reached unity for most samples (Figure and). If no depletion were present, the maximum electron density in the NC may have been even higher than what was observed. Considering that the number of CoCp*2 molecules is much larger than the number of NCs present in the solution (Figure ), the data suggest that there is a thermodynamic limit to the maximum electron density that can be transferred from CoCp*2 to the NC. Electron transfer between CoCp*2 and the NCs happens due to a difference in the chemical potential of both the species. As electrons are added to the NCs, the chemical potential (Fermi level) of the electrons increases, thereby decreasing the mismatch in chemical potential. It is possible that once a certain electron density has been transferred to NC, the chemical potential of the reducing agent equilibrates with the NC Fermi level and no additional electrons can be transferred to the NC conduction band. An increase in the Sn doping percentage increases the electron density by lowering down the energy of the conduction band minimum while the Fermi level stays at the same chemical potential. Since the absolute position of the Fermi level is not affected by the doping percentage, this thermodynamic limit is independent of the Sn doping percentage. This limit is also evident from the observation that when the chemical potential of the electrons is raised by employing larger NCs having the same doping percentage, the maximum electron density that can be transferred to the NCs decreased further to 1.4 x 10 20 cm -3 for 21 nm (Figure ). Previous reports also suggests that when a reducing agent with lower chemical potential was employed, a smaller electron density is transferred from the reducing agent to the NCs. Nonetheless, although the same ~ 2.38 x 10 20 cm -3 electron density is added to all NCs in a doping series of 8 nm Sn:In2O3 NCs, there is a larger relative change in the electron density of NCs with lower as-synthesized doping concentrations than high as-synthesized doping concentration. This increase in electron density leads to the increased LSPR frequency modulation capable at lower doping percentages (see equation 1). Once the maximum electron density <nmax> is reached and no more electron density can be transferred to the Fermi level of NCs, the electron density is likely being transferred to other chemical species such as surface ligands which leads to a loss of colloidal stability of NCs.