Microfluidics: Continuous-Flow Synthesis of Nanoparticle Dispersions for the Fabrication of Organic Solar Cells

Abstract

State-of-the-art solvents for the fabrication of organic solar cells are mostly toxic or hazardous. First attempts to deposit light-harvesting layers from aqueous or alcoholic nanoparticle dispersions instead have been successful on laboratory scale, enabling future eco-friendly production of organic solar cells. In this work, a scalable high-throughput continuous-flow microfluidic system is employed to synthesize surfactant-free organic semiconductor dispersions by nanoprecipitation. By adjusting the differential speed of the syringe pumps, the concentration of the initial solute and the irradiation of the microfluidic chip, the synthesis can be controlled for tailored dispersion concentrations and nanoparticle sizes. The resulting dispersions are highly reproducible, and the semiconductor inks are stable for at least one year. The synthesis of the dispersions is exemplified on a polymer/fullerene combination with large-scale availability.