Synthesis and spectroscopic characterization of fluorescent blue-emitting ultrastable CdSe clusters

An efficient and simple top-down synthesis and the spectroscopic characterization of luminescent blue-emitting ultrastable CdSe clusters, evolving the decomposition of initial near-critical-radius nanocrystals (NC), was demonstrated. The results show that the quantum efficiency (QE) for CdSe clusters with an initial Cd:Se ratio of 1:2 is found to be 5%. An increase in the amount of selenium results in a smaller Stokes shift, whereas a decrease in NCs could only be observed with increasing diameter. At a high cadmium precursor concentration, the smallest NCs are stabilized effectively against the degradation process, which leads to a successful synthesis of bigger CdSe NCs. The results also indicate that a 1:2 variation of the synthesis time with different Cd:Se ratios is caused by a diluted synthesis solution and the smaller amount of cadmium precursor used.