A Tokyo Institute of Technology research team has shown copper nitride acts as an n-type semiconductor, with p-type conduction provided by fluorine doping, utilizing a unique nitriding technique applicable for mass production and a computational search for appropriate doping elements, as well as atomically resolved microscopy and electronic structure analysis using synchrotron radiation. These n-type and p-type copper nitride semiconductors could potentially replace the conventional toxic or rare materials in photovoltaic cells.