The present proposal aims to develop a sustainable reaction methodology to expand the current scope of carbonylative couplings using sunlight and organic (metal-free) dyes. The planned activities are at the interfaces of photophysical, organic synthetic, and technological studies. Two novel chemical concepts are proposed: i) the use of available and reactive gases, such as carbon monoxide, for the synthesis of organic intermediates and fine chemicals via photo-redox methodology using visible light as the most abundant energy source, and ii) the development of two-photon processes for the activation of hitherto unreactive organic halides by visible light. To achieve these objectives, we will initially focus our studies on visible-light mediated photo-redox functionalizations of simple arenederivatives with common nucleophiles and study appropriate organic photocatalysts under carbon monoxide atmosphere. Secondly, light upconversion processes (from mid-VIS to high-energy VIS and near-UV) will be evaluated toward the photo-redox activation of sigma-bonds (i.e. in aryl bromides) that lie outside the energy window of the primary irradiation wavelength. We will apply such methodology to novel synthetic carbonylations which result in the formation of various industrially relevant benzoate, phenone, and chalcone derivatives. Finally, commercial microflow reactors will be equipped with a transparent reaction chamber in order to demonstrate the potential of the combination of photo-redox and high-pressure methodologies for continuous synthesis. Both concepts rely upon high dispersion and rapid mixing, so that microreactors contribute to the overall reactivity.