Enhancement of the near-band-edge emission of CuI by Cl doping

CuI is a promising candidate for scintillation devices due to the ultrafast decay time of 130 ps at room temperature. The photoluminescence of CuI is composed of the near-band-edge emission (fast decay) and the deep-level emission (slow decay). Unfortunately, the fast component is much weaker than the slow component. The effect of Cl doping on the fast and slow components is investigated in this paper to improve the luminescent and scintillating properties. X-ray diffraction patterns show that Cl ions are successfully doped into CuI lattice for low concentration (< 10 mol%), whereas the CuCl phase is formed for high concentration. The Cl doping forms isoelectronic bound excitons and enhance near-band-edge emission and suppress the deep-level emission, which is demonstrated to be stable for long time. Furthermore, the near-band-edge emission decay times of CuI hardly change with Cl doping.