Optoelectronic Materials, and semiconductors in particular, are the building blocks for most of today's high-tech gadgets and instruments. They also provide unique insights into materials properties, due to their extreme sensitivity to even the slightest changes of composition. The central role of chemistry in conducting both goal-oriented and curiosity-driven research in this area is obvious: only through chemistry can we hope to change and control composition. At the same time, it is physics that allows us to model their behaviour with predictive power.