White-light emitting (WLE) CdSe quantum dots (QDs) capped with oleic acid (OA) were synthesized and the effects of thermal annealing and photoactivation on the small CdSe QDs in (polymethyl methacrylate) (PMMA) were investigated. A bimodal size-distribution phenomenon induced by annealing at temperatures of ∼200 °C was observed. The phenomenon observed here is different from the result of large CdSe QDs with the similar treatment. The size-dependent property arises from the fact that smaller QDs have a higher surface energy than larger ones.
Annealing-induced bimodal size distribution results in a luminescence change of small CdSe QDs.