Synthesis of quasi-two-dimensional colloidal cadmium selenide nanoparticles and formation of sulfide monolayer on their surfaces

We have carried out a solution synthesis of quasi-two-dimensional CdSe nanoparticles (nanoplates) using oleic acid as a stabilizer. Three populations of CdSe nanoplates with different thicknesses quantified by one CdSe monolayer were obtained. The absorption spectra of CdSe nanoplates exhibit narrow excitonic bands (with bandwidths of ～60 meV), whose positions are determined by the nanoplate thickness and are 461, 503, and 551 nm for the three populations. We have systematically studied how formation of sulfide monolayer on the surface of CdSe nanoplates affects their optical properties. The red shift and significant broadening of absorption bands was shown.