Reconsideration of relaxation processes of excitons in CuCl nanocrystals

Abstract

We report temporal changes of luminescence and induced absorption of excitons in nanometer-size semiconductor crystals (nanocrystals) of CuCl embedded in NaCl or in glass, and discuss relaxation mechanisms of the excitons. In CuCl nanocrystals in NaCl, luminescence-decay or -rise is observed at “free”- or “localized”-state luminescence, respectively. This indicates nonradiative relaxation from the “free” exciton to the “localized” state. In CuCl nanocrystals in glass, the temporal changes of the induced absorption have a longer decay component, in addition to a fast decay component which agrees with the luminescence decay. This result suggests exciton decomposition and existence of an electron remainder in the nanocrystals.