Semiconductors, which are the very basic components of electronic devices, have improved our lives in many ways. They can be found in lighting, displays, solar modules and microprocessors that are installed in almost all modern day devices, from mobile phones, washing machines, and cars, to the emerging Internet of Things. To innovate devices with better functionality and energy efficiency, researchers are constantly looking for better ways to make them, in particular from earth-abundant materials using eco-friendly processes.