Deposition of quantum dot (QD) films is often a laborious process, particularly as films become thicker, encompassing many deposition and ligand exchange steps. However, alternatives to the most common techniques of QD film deposition (spin-coating and drop-casting) are rapidly gaining momentum within the field as possible techniques for controlled selective deposition. Electrophoretic deposition (EPD) is an emerging technique with the possibility of creating order QD films using an electric field, introduction of a non-solvent to reduce the nucleation barrier, and maintenance of a wetting environment to promote QD organization. Combined with an in-solution QD ligand exchange, EPD has the capability to produce compact ordered QD films in a single deposition step. Using PbSe QDs capped with NH<sub>4</sub>I ligands, dispersed in 2,6-diflouropyridine, we can deposit QD films of several microns in thickness, with deposition speed being controlled by the strength of the applied electric field. Using SEM and GI-SAXS data we determine that addition of hexane as a non-solvent in a 1:1 ratio produces the best ordering, while a higher ratio leads to faster film growth. The limiting factor in film thickness is the structural integrity of the film, as we begin to see flaking and curling of the thicker films upon removal from the solvated environment.

Single step deposition of compact quantum dot films

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ACS Fall 2022

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