Solvothermal Synthesis And Properties Of â…¡-â…¥ Group Quantum Dots

Semiconductor quantum dots(QDs) are a kind of three-dimensional confined cluster with special physical effects,such as quantum size confinement,quantum tunneling,and coulomb blockade.In recent years, QDs have been widely used in biology and medicine,especially in multiplexedbiological detection,labelling and imaging due to their excellent optical properties.This paper investigated the preparation ofⅡ-Ⅵgroup QDs with different morphologies by a solvothermal method and studied the crystal structures,morphologies and fluorescence properties of the product.First,CdS and CdSe nanorods with a diameter of about 40 nm and length of several hundreds nanometers to several microns were synthesized by using ethylenediamine(EDA) as the solvent with the reaction conditions of 180℃and 12h.Changing the reaction time had little effect on the product,and the product became irregular lump when the reaction temperature was below the boiling point of the solvent. Second,CdS and CdSe QDs with a diameter of about 4 nm was synthesized with the reaction conditions of 80℃and 10h by using triethanolamine(TEA) as the solvent and adding ethanol to control the reaction temperature in the system as low as possible.Dispersion of the QDs was improved when a small amount of NaOH was added into the solvent.The as-prepared CdS and CdSe QDs have strong emission peaks at 410nm and 490nm,respectively,and exhibit obvious blue shift compared to the bulk materials.The CdS and CdSe QDs have quantum yields of 7.4%and 6.9%, respectively.Finally,CdS_xSe_1-x ternary composite were synthesized by using EDA and TEA as the solvent,respectively.CdS_0.58Se_0.42 and CdS_0.75Se_0.25 nanorods with a diameter of about 40 nm were obtained in EDA,while CdS_0.58Se_0.42 and CdS_0.33Se_0.67 nanoparticles with a diameter of 4 nm were obtained in TEA.The emission peak positions and quantum yields of the ternary composite varied compared to CdS and CdSe.