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

La perspectiva de género en la televisión: una urgencia impostergable

International audienceAccording to a national survey on language usage, Veneto dialect (spoken in Veneto, one of Italy’s northeastern regions) benefits from the widest usage range compared to other regional dialects spoken in the Italoromance domain. We collected 35 hours of interactional data and conducted attitudinal interviews. From these data, we examined a family’s language policy (nuclear and extended family) and its influence on a child’s (Francesco, aged 17–30 months) language environment and acquisition of norms of usage. The juxtaposition of the attitudinal interviews of the adults in Francesco’s environment with the interactional data collected revealed numerous discrepancies between the adults’ expressed attitudes and their production. We argue that attitudes do not necessarily predict language choices and that the relationship between the two is more complicated than a cause-and-consequences one, in particular when these concern dialect usage. Rather, there is a dynamic link between attitudes and language choices as these are constantly (re)defined, negotiated and reconfigured during interaction