Abstract
The temporal behaviour of the photoluminescence (PL) due to excitons and biexcitons have been observed in CuBr nanocrystals (NCs) embedded in poly methyl methacrylate (PMMA). In the excitation intensity less than 0.5 v; µJ/pulse, the decay time of the exciton PL is evaluated to be 30 v; ps. In the excitation intensity more than 0.5 v; µJ/pulse, a new fast component appears in addition to the above component, and the decay time is evaluated to be 0.8 v; ps. In'contrast, the temporal behaviour of the biexciton PL does not depend on the excitation intensity, and the biexciton formation time is evaluated to be about 0.8 v; ps. The facts suggest that two excitons are photo-generated in one NC under a strong pulse radiation, and then a biexciton is formed or one of them is annihilated radiatively without inelastic collision with each other.
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