This chapter focuses on imagers, the array of light detectors able to transduce an optical image into a digital one, represent a paradigmatic application for Organic semiconductors (OSCs). OSCs refer to carbon-based compounds, small molecules, oligomers, or polymers where carbon is present in its sp hybridization form; this gives rise, in addition to highly energetic and localized σ-bonds, to delocalized π-bonds. The physical, chemical, and electronic properties of OSCs can be tuned by means of chemical tailoring, giving an unprecedented freedom in the adaption of semiconductor properties to the application. Most OSCs can be processed by solution-based processes with a limited thermal budget: this makes the process far more eco-friendly than inorganic semiconductors and allows for direct deposition onto lightweight, flexible substrates. All the basic building blocks of electronics can be realized with OSCs: diodes, organic light-emitting diodes, thin-film transistors and circuits, memories, solar cells, and, of course, organic photodetectors.