Quantum dot light emitting diodes (QD-LEDs) are promising devices for the next generation of solid-state lighting and other optoelectronic applications. QD-LEDs have several potential advantages over current technologies due to the unique properties of quantum dots, such as a very narrow and easily tunable emission bandwidth, broad excitation spectrum, high brightness, and improved shelf life over organic dyes (used in organic LEDs) ^{[1] [2] [3]} . Quantum dot films for QD-LEDs are conventionally formed via spin-casting, which is a reliable but highly non-scalable process. To date, a few alternatives to spin-casting have been researched, but due to its simplicity, spin-casting remains the most common technique for forming dot films for QD-LEDs.

We investigated electrophoretic deposition (EPD) as an alternative method to spin-casting for the deposition of quantum dot films. Electrophoretic deposition is an experimentally simple, well-established technique that has been used to deposit a variety of materials ^[4] . In addition to offering the potential for parallel processing and for less material waste during processing, EPD could potentially create more ordered films than spin-casting. We fabricated QD-LEDs (Figure 1) with an electrophoretically deposited CdSe/ZnS core-shell QD film. EPD is performed by submerging 2 ZnO-on-ITO electrodes into a solution of QDs in a sonication bath and applying a DC field of ~25 V/cm for 5 minutes between the electrodes. Completed QD-LEDs fabricated with an electrophoretically deposited dot layer exhibited sub-bandgap turn-on voltages of ~1.8 V and peak external quantum efficiencies (EQE) of ~1.6%, a number comparable to that of QD-LEDs fabricated with a conventional spun-on dot layer (Figure 2). These findings demonstrate that EPD is a viable alternative to spin-casting for the large-area, high-throughput fabrication of QD-LEDs with respectable performance.

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