The Importance of Semiconductor Miscibility for the Formation of Light‐Harvesting Polymer:Fullerene Nanoparticle Dispersions

Abstract

Light‐harvesting layers in organic bulk‐heterojunction solar cells are commonly fabricated from aromatic solvents which are often toxic or hazardous. To fully omit harmful solvents, (surfactant‐free) nanoparticle dispersions of organic semiconductor blends are investigated, but only a very limited choice of materials form blend nanoparticles. This work is a systematic study of the nanoparticle formation by nanoprecipitation of electrostatically stabilized polymer: fullerene blends. It turns out that miscibility of both components is crucial for the incorporation of the fullerenes into the nanoparticles. This finding demystifies why certain polymer:fullerene combinations seemingly randomly form stable nanoparticle dispersion while others do not. The need of miscibility constitutes an important design criterion for processing future semiconductor blends along the nanoparticle route. Some mitigation to the unwanted release of larger amounts of fullerenes can be achieved by using ternary semiconductor blends.