The invention relates to novel organic semiconducting compounds containing one or more dialkylidene-s-indacenodiheteroarene groups, methods for their preparation and educts or intermediates used therein, polymers, blends, mixtures and formulations containing them, the use of the compounds, polymers, blends, mixtures and formulations as semiconductor in organic electronic (OE) devices, especially in organic photovoltaic (OPV) devices, and to OE and OPV devices comprising these compounds, polymers, blends, mixtures or formulations.