“…The zincblende phase of CuI, γ-CuI, has particularly interesting electronic properties and therefore has been attracting increasing interest 12,19,21,24 . With a bandgap of around 3.1 eV 19,25 , large exciton binding energies of 62 meV 25 and high hole mobilites 26 of µ > 40 cm 2 V −1 s −1 in bulk single crystals, γ-CuI is a suitable transparent ptype material for optoelectronic applications. Until now, the application potential of CuI has already been demonstrated in transparent p-n heterojunctions 27 , thin film transistors 2,28,29 , light-emitting diods 30,31 , perovskite solar cells [32][33][34] , UV-photodetectors 35 and thermoelectric devices 5 .…”