Scanning transmission electron microscopy (STEM): The average NC diameter, polydispersity and morphology of the Sn:In2O3 NCs were examined through low-resolution STEM microscopy on a Hitachi S5500 operating at an accelerating voltage of 30 mV in the STEM mode. Sample were prepared by drop-casting a 20 μL dilute solution of NCs in hexane (~15 mg/mL of NCs in 1 mL hexane) on a copper 300 mesh TEM grid and drying it in vacuum overnight. The average NC diameter and standard deviation in sizes of different NCs were determined by analyzing 200-300 particles from their respective STEM images using ImageJ software and fitting the statistics to a Gaussian size distribution.