A new problem that our world confronts is that the commercialization of emergent devices with uncertain health and environmental compatibility raises serious concerns and hampers societal acceptance. The problem applies also to Optoelectronics market which is a key area with applications in our everyday life such as in solar panels, TV displays, smartphones, street lights etc. To address the risk of low environmental impact, researchers typically adopt sophisticated recycling procedures which however add cost in technology. This presents a grand challenge that MIX2FIX will address directly. Such devices should be timely replaced by equally smart but simultaneously sustainable alternatives. An emerging technology, called lead halide organic-inorganic perovskites, is a characteristic example of a device being at the stage of pre-commercialization. Solar cell and LEDs have shown boundary-pushing efficiencies thus far but at the expense of environmental compatibility; perovskites can decompose in humid air and release water soluble, toxic lead into the environment through the biogeochemical cycle. Therefore it is very challenging to unleash perovskite technology by developing the next generation of optoelectronic devices with the exclusive use of eco-friendly materials, by preserving similarly high performance and low cost. To tackle this challenge, MIX2FIX proposes to develop a new class of solution-processable optoelectronic devices based on air-stable, non-toxic metal chalcogenides endowed with an organic part, which will facilitate solution-processing and potentially enrich the compounds with the spectacular properties of halide perovskites. To achieve this, the CoG project has set the following overall objectives: (i) developing optoelectronically-active, organic-inorganic chalcogenide thin films films that have never been explored before, by mimicking strategies from established perovskite technology, (ii) devising means to improve their optoelectronic quality so as to be comparable with the best single-crystal semiconductors and (iii) implementing optimized materials into boundary-pushing PV and LED devices. Addressing these objectives, this project will therefore permit the transition for emerging optoelectronic materials from toxic lead halide perovskites to green hybrid chalcogenides.