Fabrication of Organic Solar Cells from Surfactant‐Free Aqueous Nanoparticle Dispersions

Light-harvesting layers in organic bulk-heterojunction solar cells are commonly fabricated from aromatic or even chlorinated solvents, which are often toxic or otherwise hazardous. In this work, nanoparticle dispersions of a blend of poly(3-hexylthiophene) and [6,6]-phenyl C$_{71}$-butric acid methyl ester (P3HT: PC$_{71}$BM) are synthesized in water, omitting any stabilizing surfactants which would remain in the layer and hamper the device performance. To overcome wetting issues and to master the deposition of thin films from aqueous dis- persions, co-solvents are employed. The solar cells exhibit power conversion efficiencies of 2.7% and show excellent long-term stability, paving a promising way towards the all-eco-friendly production of organic solar cells in the future.