Synthesis of highly luminescent Cd(Se,S) nanocrystals

Highly luminescent semiconductor nanocrystals with graded band gap were synthesized using a hot injection method. The band gap of nanocrystals were controlled by gradual incorporation of sulfur to CdSe nanocrystals by applying severely asymmetric composition of reactants [(Cd)/(Se,S) ≫ 1]. The maximum emission wavelength of the grown nanocrystals was varied by controlling the concentration ratio of VI group element, i.e. Se and S. A green light was emitted from Cd(Se,S) nanocrystals with [Se]:[S] = 1:3 in the reactant mixture and the maximum quantum yield measured by comparing with Rhodamine 6G was larger than 80%.