Revisiting Solvent Additives for the Fabrication of Polymer:Fullerene Solar Cells: Exploring a Series of Benzaldehydes

The power conversion efficiencies of organic solar cells delicately depend on the morphology light-harvesting bulk heterojunctions (BHJ). Upon deposition from solution, formation tailored bicontinuous networks polymers and fullerenes is often achieved using combinations solvents solvent additives. Common wisdom infers that best cell performances are when additives exhibit excellent fullerene solubility. Herein, this concept revisited based investigation a series structurally similar, substituted benzaldehydes. It concluded do not only have to feature commonly accepted good solubility, but must also lowest polymer solubility suppress liquid–liquid demixing hence achieve performance. Thus, study adds an important item list selection criteria toward production polymer:fullerene with optimized efficiencies. microscopic picture resulting domain configurations within layers developed around comprehensive multiscale investigations BHJ morphology, atomic force microscopy, scanning transmission electron nano-infrared microscopy. latter operated in two complementary modes, one which more sensitive, whereas other mode surface sensitive.