ZnSe NC Ligand Stripping and Transfer to DMF

The as-synthesized ZnSe NCs were first diluted to a final concentration of ∼16 μM in toluene with a small amount of DMF (10% v/v). In parallel, a BF₄^– solution was prepared by dissolving trimethyloxonium tetrafluoroborate in acetonitrile (∼1 M). The two solutions were then mixed together in a 1:1 ratio and cleaned twice, using DMF as the solvent and toluene as the antisolvent. Finally, the BF₄^– surface-treated ZnSe NCs were dispersed in DMF to the desired concentration for EPD (∼4 μM, O.D. = 3 at 420 nm).