Cuprous iodide (CuI) has attracted much attention in the field of radiation detection due to its ultra-fast scintillation property with a decay time about 90 ps for gamma phase crystals.[1,2] CuI belonging to a wideband-gap semiconductor with a band-gap of 3.1 eV has near-band-edge emissions including free exciton transitions and interband transitions which are parity allowed,leading to a fast decay time less than nanosecond.The emission wavelength ranges from 400 to 430 nm.