All-Inorganic Nanocrystal Thin Films Fabricated By Low-Voltage Electrophoretic Deposition

Abstract

The solution processability of colloidal nanocrystals (NCs) offers prospective next-generation solar cells significantly reduced fabrication costs, yet methods for scalable deposition of conductive, well-adhered NC films have yet to be realized. Electrophoretic deposition (EPD), a low-waste, high-throughput technique used commercially in other fields, is proposed for depositing solution-processed absorbing layers for solar cells. Here we share methods for fabricating all-inorganic semiconductor-NC films through low-voltage EPD. Through light scattering, absorbance spectroscopy and electric measurements, the fundamental electrochemical reactions and transport processes that occur during EPD are studied. Special emphasis is applied to elucidate the requirements for low-voltage EPD of semiconductor NCs. Through insights gleaned from this study, choice of NC-ligand-solvent combinations and reactor design, film electronic properties and morphology improvements are realized. Low-voltage EPD is demonstrated using both continuous flow and batch reactors in this study.